How to fasten wooden parts without nails, glue and screws. Types of wooden connections

Making furniture with your own hands is becoming increasingly popular due to the high cost of finished products, and due to the large number of source materials that appeared in the public domain. At home, with a minimum set of appropriate tools, it is realistic to assemble viable furniture that will serve properly and please with its appearance. One of the most popular joining methods is gluing, which makes it possible to obtain strong, monolithic parts. Gluing can be used as an independent fastener or as a duplicating one, when using external elements, such as dowels, dowels or self-tapping screws.

Do-it-yourself glued wood

Before gluing, the parts are processed, this is done not only to clean the surface, but also allows you to open the wood pores. When applied, the adhesive composition penetrates through the pores into the wood structure, into the intercellular space, and when solidified, it forms a multitude of the thinnest threads (cobwebs) that reliably “seam” the workpieces together. The strength of a correctly made seam exceeds the strength of the wood itself; when testing for fracture, the part breaks not at the place of gluing, but along the whole tree.

Gluing a tree allows you to get products with better parameters than massive ones. In the process of gluing, elements that are suitable in texture and shades are selected, damaged, cracked and knotty areas are rejected. As a result, the strength of the glued parts is greater than that of the usual one, and by gluing the thinnest veneer onto the front surfaces, the products are given the appearance of the most valuable rocks. Wood glued according to all the rules warps, cracks and cracks much less than solid wood.

How to glue wood. Technology

There are several ways to connect parts when gluing.

• Gluing wood onto a smooth joint - joining smooth details without increasing the penetration area.

• Gluing on a microthorn - an increase in the penetration area by 2.5 - 5 mm due to the creation of a jagged relief on the part (using a milling cutter).

• Bonding on a toothed spike – increase in the penetration area by 10 mm due to the creation of a toothed spike.

• Gluing on a tongue-and-groove (thorn-groove, dovetail, oblique tenon) - additional grip due to the groove connection.

Although in certain situations where special conditions of use are expected, tongue and groove joints are relevant, in most cases the parts are glued to a smooth reveal. Modern adhesives penetrate deep into the structure and create a strong seam without additional sampling of wood.

How to glue boards together. Options

The wood to be glued must have a moisture index in the range of 8 - 12%, maximum - 18%. If there is a need to glue wet parts, a special compound is used; during the hardening process, it draws moisture from the wood. When gluing blanks with different moisture content, a difference of more than 2% is not allowed in order to avoid internal stress in the glue line due to deformation of the wetter part. The temperature of the glued workpieces varies between 15 - 20⁰С, so the work is carried out in warm rooms (18 - 22⁰С). In the cold, most compositions crystallize, which leads to a deterioration in the quality of gluing and makes the process difficult.

The final preparation of wood (planing, jointing, sanding) is carried out immediately before gluing in order to increase the permeability of the adhesive and avoid warping. It is important not only to select parts according to their dimensions, structure and external data, but also to arrange them correctly.

• When gluing along the length, only one type of sawing is used - tangential or radial;
• When gluing, both in length and in width, alternation of different parts of wood is not allowed - the core is laid with the core, sapwood (young, extreme part) with sapwood;
• Annual rings of adjacent blanks from boards or bars should be directed in different directions or at an angle to each other from 15⁰.

The standard thickness of furniture boards is 2 cm, but in order to glue wooden boards at home, when choosing boards for a board, the estimated waste during processing is taken into account, so the workpiece is selected with a thickness of up to 2.5 cm. The excess will be removed during the primary processing, when defects are eliminated, and after gluing, when grinding the shield. If you dissolve a board 5 cm thick for a furniture board, you get two blanks with the same texture and shade, which increases the decorative effect of the product. For shields, boards of wood of the same species are selected, up to 120 mm wide, so that it is possible to process the edges of the shield with high quality, the length of the blanks should have a margin (2 - 5 cm).

Adhesives

Adhesives used for the manufacture of laminated wood fall into two main groups.

Synthetic - obtained on the basis of resins or polyvinyl acetate dispersions (PVA). They are characterized by increased strength of the resulting connection, moisture resistance, biostability. The disadvantages include the presence of harmful substances that can be released into the environment during operation and further operation. This is "famous" for compositions based on phenol-formaldehyde resins. Modern PVA dispersions and their derivatives are non-toxic and are commonly used in the domestic area and are considered universal for wood. The bulk of synthetic mixtures are ready for use. The epoxy adhesive needs finishing, to work with it the hardener included in the kit is mixed with epoxy resin.

Natural mixtures - animal, vegetable, mineral. They are safe, give a strong connection, but are produced in the form of semi-finished products that are prepared before use. How to glue a tree with them: when preparing, you must strictly follow the instructions and observe the dosages, otherwise the quality of the glue will not allow you to get a strong connection. To prepare the adhesive, it is usually necessary to dilute the powder concentrate with water to the desired consistency (may require a certain swelling period) or to melt the solid particles. Direct exposure to fire is not allowed, apply " water bath”, on which the mass with the addition of water after swelling melts to a homogeneous consistency.

How to glue a tree

When gluing wooden surfaces glue is applied to both parts in an even layer. The thickness of the layer depends on the type of glue, its consistency and the type of surfaces to be glued - the thinner the wood, the thinner the layer. The glue should moisten the part, but not excessively; when connecting the elements, an even roller should stand out. Adhesive streaks are removed from the surface as soon as they grab a little, with a scraper or spatula. Cured excess glue greatly spoils the appearance of parts and complicates their further processing.

How to glue a wooden blank.

After applying the adhesive, the parts withstand a certain period of time, this allows the composition to penetrate deeper, at the same time excess moisture evaporates, the concentration of adhesives increases. During exposure, it is not allowed to air the seam in a draft or dust it. Some varieties natural glue(bone, skin) must be applied hot, instantly fastening the parts without aging, as the composition loses its properties as it cools.

Wood Gluing Tool

To obtain the most durable connection, when gluing, the wood is pressed in - compressed by means of special presses. At home, for these purposes, improvised tools and means are used - a vice, clamps, cam devices, frames made of metal corner With clamping mechanisms. The pressure during wood pressing is maintained in the range from 0.2 to 1.2 MPa. possible in production large quantities, at home, such indicators are enough for the structural details to stick together.

Glued wood with your own hands.

Subject to the gluing technology, the adhesive seam is strong and reliable, and, unlike the method of connecting parts with metal fasteners, does not spoil the appearance.

For fans of creating household items on their own, a topic is open on FORUMHOUSE. How to organize a convenient corner for working with wood can be found in the article. The video about wooden elements in a country house shows interesting products made by users of the portal.

The tree is widely used in various areas of human household activities. Especially widely wooden structures are used in construction. However, any wooden structures consist of separate parts that must be connected together in one way or another.

There are several types of connections. But you need to learn one rule: before starting work, you need to carefully mark out future cuts and always follow the markup. In the final product, the parts must fit exactly and tightly.

Methods for connecting boards and bars of small length: 1 - "butt" (butt); 2 - "in the groove and crest"; 3 - "on the mustache"; 4, 6 - "toothed" adhesive; 5 - "half a tree"; 7 - "on the rail"; 8 - "direct lock" overhead; 9 - "oblique lock" overhead; 10 - "straight" and "oblique" tension locks.

The simplest and relatively fragile is the "butt" connection. For this connection, the ends of the fastened parts are made clearly rectangular, and the ends are processed with a planer.

The mustache connection is similar to the butt joint, but here the ends of the parts are beveled at an angle of 45o. For accurate marking, a device called a yarunok is used. Such a connection is strengthened with a plywood lining or a metal square. Strengthen the connection "in the mustache" with fastening with inside square or triangular beam.

More durable connections include “overlay” connections by making saw cuts. If the parts to be joined are of the same thickness, then cuts are made on both parts for half of their thickness. In the case when one part is thicker than the other, then the cut is made only in a thicker part. To enhance the strength of the parts are glued and additionally fastened wooden dowels or screws.

If it is necessary to obtain a T-shaped connection, a half-tree overlay is used. In this case, both parts are cut if they are of the same thickness, or a thicker part is cut off with different thicknesses of the fastened elements.

The most durable connections that have come down to the present time from ancient times are connections with through spikes, on two plug-in round spikes and in the middle knitting method with a single spike. Details connected by a straight through spike are additionally fastened with dowels and glued. To make a connection on two round plug-in spikes, use a template pad made of plywood or thick cardboard to accurately drill the holes for the spikes. The median knitting with a single spike is deaf if you need to hide the end of the spike on front side, and through, which is much stronger than deaf.

For box joints, spiked joints with straight and oblique ("dovetail") spikes are used. Despite the higher labor intensity, the connection with oblique spikes is more durable and reliable.

For reliability, all joints can be strengthened with dowels, gluing, nails, screws, bolts, and a combination of these joint strengthening techniques.

Nagel is made in the form of a wooden rod with slightly pointed ends from hardwood. If the product will subsequently be painted or varnished, then the outer end of the dowel is recessed and puttied or a blind hole is drilled for the dowel.

Before gluing, the parts are thoroughly dried, the surface is cleaned of dirt, grease and oil stains, dust and roughened with a rasp for better adhesion. Moreover, hardwood parts are glued more liquid composition, and soft wood is denser because it absorbs moisture much better. The surfaces to be glued must be carefully smeared with glue, which significantly increases the strength of the connection. The adhesive layer should not be too thick or too thin. This will significantly degrade the quality of the connection. The adhesive is applied in a uniform, dense, non-breaking layer. For reliable bonding, the product must be kept for at least a day before being subjected to further processing.

For gluing, carpentry or casein glue is used. Wood glue is not waterproof and high humidity finished products may be sticky. Therefore, it is recommended to use casein glue, devoid of this drawback. In addition, casein glue is somewhat cheaper, and the bonding strength is slightly superior to carpentry.

For extra strength joints wooden structures fasten with nails, screws and bolts. The length of the nail or screw is selected 3–5 mm shorter than the total thickness of the parts to be joined, and when connecting parts of different thicknesses, the length of the fasteners should be 2–4 times the thickness of the thinnest part.

It should be borne in mind that screws and nails screwed or hammered across the fibers hold the parts better.

The part of the bolt that extends beyond the parts to be joined should be slightly larger than the thickness of the nut. Washers are placed under the bolt heads to protect the wood from crushing. The slots of the screw heads are parallel to the wood fibers. It is desirable to place the slots of all screws on one straight line or parallel to each other. Before screwing in thin screws or driving in thin nails, it is recommended to make signal holes with a smaller diameter.

Screw connections are considered the strongest. You need to be careful not to split the tree. For this purpose, screws and nails should not be driven in and driven close to the edge and to each other.

It's not a secret for anyone that it is quite difficult and almost impossible to make something completely from solid wood without a single fastening, without dividing the product into parts. In addition, deforestation is not proceeding at such an accelerated pace as before, so acquiring a large amount of wood is not a cheap pleasure. If you accidentally make a mistake, you can ruin the entire bar. It is much easier to divide the drawing into separate parts, rather than sawing out every bend or notch, constantly turning the whole product over. In this case, all individual parts must correspond to the dimensions, and when connected, form a single whole. In addition, an important factor in the strength of the product will be the accuracy and strength of the connections.

Connection types

All connections, whether carpentry or joinery, are called landings, because they are based on the principle of fitting a part with a tenon onto a part with a groove. Depending on how tightly the parts in the mount are in contact, all landings are divided into tense, tight, sliding, loose and very loose. At the heart of all connections is the knot - the place of attachment. Depending on what shape the connected parts resemble and how the node is located, there are several types of connections. Among them are end, side, corner, t-shaped and cruciform.

End connection

Rice. 53.	Rice. 54.
Rice. 55.	Rice. 56.
Rice. 57.	Rice. 58.

There is another definition of such a connection - extension. It is characterized by the fact that all parts are fastened together in the end part, while the length of the whole part increases. Depending on the type of attachment, these end connections can withstand high compressive, tensile, and flexural loads. The usual whole board here is in many ways inferior to the board obtained by building.

The end connection of parts that resist compression may have different design. The main feature of this connection is that each bar has both an overlay and a groove, which are most often made equal in both thickness and length. You can make extensions with a straight overlay in half a tree (Fig. 53) or end connection with an oblique overlay (Fig. 54).

If there is no confidence in the strength of the future connection, you can further complicate it with spikes or various joints. Naturally, this connection requires additional adhesive fastening or fastening with nails and screws. The end connection of parts that resists stretching, at the heart of its design, contains an overlay in the lock. First of all, you need to draw an overlay. Then make a groove on one part, and a ledge on the other. It is this lock that will allow both halves to avoid separation.

As well as a connection that resists compression, this type of connection can have a straight (fig. 55) and an oblique lining (fig. 56). As an additional fastener, you can use glue, nails or screws. An anti-bow end connection basically uses either a beveled escutcheon (fig. 57) or a stepped apex (fig. 58).

A feature of the first type of connection, where an oblique joint is used, is that the end sides of both parts are cut at an acute angle. At the same time, when sawing the ends, it is necessary to observe the cut angle with an accuracy of up to a nanometer. The second type of connection is characterized by the fact that there are small grooves and spikes on the end sides of the parts. Both listed types of connections must necessarily have a straight lining surface. Overlays with an oblique surface are rarely used, although they are not inferior in strength to straight ones. For additional fastening, glue, screws or nails can equally be used here.

Additional fastening of large beams used in the construction of houses can be metal or wooden. As wooden fasteners spikes are used, both hollowed out and inserted. Metal fasteners can be in the form of clamps or winding with thick wire. Often bolted.

Side connection

Rice. 59.	Rice. 60.
Rice. 61.	Rice. 62.
Rice. 63.	Rice. 64.
Rice. 65.	Rice. 66.

Lateral connections are also called rallying. Most often, such a connection is used when installing floors, doors or gates. This is a fairly strong connection. Large arrays that result from such a connection are additionally fastened with transverse boards or shields. If the details are smooth surface side edges and when connected, they are simply glued together, then such a connection is called lateral to a smooth fugue (Fig. 59). If in each part on the side there is a groove along the entire length, into which the connecting rail is inserted, then this type of connection is called side to the plug-in rail (Fig. 60).

If a quarter is removed on the sides and the parts are attached with their help, then such a connection is called a side quarter (Fig. 61). The next version of this connection is the lateral groove and tongue connection, which has several types depending on the quality of the tongue. This groove can be either triangular (Fig. 62) or rectangular (Fig. 63).

Used for roofing next type lateral connection, which promotes the best stock precipitation from the surface and greater protection of the coating from the damaging effects of atmospheric phenomena. This type of connection is called side overlap (Fig. 64). You need to connect the parts in the following way: a thin rail is placed under the lower bar and the upper side edge of the part is fixed with nails, then the next bar is installed, making a small overlap equal to 1/4 of the bar thickness with its lower edge, and also fixed with several nails.

Also, to connect several parts at once into one whole with the help of only one, you can use rallying with a tip (Fig. 65). This type requires the same notch on the side of the single part and on the front side of the parts to be joined. Most often it is used in the preparation of parquet floors. As a decorative technique, a side connection with an overlap is most often used (Fig. 66), which not only decorates the surface, but also contributes to greater sound and heat insulation. Such a connection is made as follows: first, through a gap equal to half the width of the bar, the first row is laid. Then a second row is installed on top of it on the part, which closes the voids.

T-connection

Such a connection is named because of its appearance. After fixing the parts, the inserted part, as it were, grows out of the array of the other. Most often, this type of connection is used when pairing lag floors and partitions with house piping. The angle at which the parts are connected must be 90 °. At other angles, the connection is fragile and very quickly becomes unusable.

Among the many varieties of t-shaped connection, type 2 is the most common. The first type uses a hidden spike, which has a trapezoid shape and is inserted from one side of the beam (Fig. 67). The second type uses a stepped straight overlay for fastening (Fig. 68). In order to make such an overlay, you will first need to make a regular overlay, choosing wood from one part to 1/2 of the entire width, and on the other part to 1/3. Then, on the first part, the wood is selected on half of the lining by another half, thereby the thickness of the unaffected part of the bar will be 1/4 of the width of the whole bar. On the second part of the structure, where initially only 1/3 of the wood was selected, a small recess is made so that the unaffected wood is 1/2 of the entire thickness of the bar. Such a stepped overlay is considered the most durable. For additional fastening, glue is mainly used here. Screws and nails can only damage the integrity of the steps.

Rice. 69.

For the installation of roofs and trusses, this type of fastening is most often used, such as a cross, a bit reminiscent of a T-shaped. But here both levels can be called equally leading (Fig. 69). Varieties of such a connection differ only in the depth of the mounting plate: from 1/6 of the thickness of the bar to 2/3.

Gusset

This type of fastening is most often used in fastening window, door blocks and greenhouse frames. Corner connection differs from others in that the parts to be joined are located relative to each other at an angle of 90 °. Depending on the fasteners used, all corner joints are divided into tenon joints and mustache joints.

Corner connections on the spike have several varieties. A through connection on a spike (Fig. 70) can use from 1 to 3 spikes in its design, and with an increase in the number of spikes, the strength of the fastening also increases. A non-through connection differs from a through connection in that the spike fastening occurs in the middle of the parts and remains invisible from the outside. In this case, small recesses are made inside the blanks for the spikes, which will be slightly deeper than the spikes themselves, so that there is room for glue (Fig. 71).

Corner joints on a mustache are distinguished by the fact that the sides of the parts connecting to each other are cut at an angle of 45 °. As well as spike connections, mustache fasteners can be through, in which rallying is visible, and non-through, when the fastener itself is fixed inside the parts. A through connection with a mustache (Fig. 72) can be strengthened with both 1 spike and 3. The principle of fastening here remains the same as with an angular non-through connection with a spike. With a non-through connection, it is impossible to see the position of the spike. Here, both round spikes and flat ones can be used equally - the fastening from this will not weaken in any way (Fig. 73).

When selecting wood for spikes, be sure to make nests a little larger than the spikes themselves, so that later the blanks are easily connected to each other. To build a roof, you need to master 2 more types of connections: a corner cut and a cut into a paw.

corner cut

This type of connection can be attributed to the angular types of fasteners, since the parts are relative to each other at a certain angle. Depending on the magnitude of the angle, 2 types of such a connection are distinguished, which are equally perpendicular to the acting force of the connection - compression. The first of them is used only when the angle between the parts does not exceed 45 °. First, wood is cut out with an insert, and then the base surface is adjusted under it (Fig. 74). The second type of connection requires an angle of at least 45° between the connecting parts. The cut here is made somewhat differently than in the first type, and consists of two planes located at different inclinations to the original surface of the base (Fig. 75).

This type of connection is used only in the construction of a wall frame or a well. Most often, such a mount is made simple, since it is already strong, but there are also some design complications in the form of additional overlays. To get a cut, you need to trim the end of the log, forming a cube, and divide its sides into 8 parts. Then a trapezoid is cut out of the cube on the end surface, one base of which should be 6 parts, and the other 4 parts. The paw from the side along the fibers should also have the shape of a trapezoid, gradually tapering towards the base of the bar. Near the bar, the thickness of the trapezoid should be approximately 2-3 parts, and from the end - no more than 6 parts (Fig. 76)

Rice. 76.

Additional fasteners used when connecting parts

Often, rallying and building up is not enough, and the connection itself has to be repaired after a few years. In order for the connection to last longer, it is specially fixed with various wooden or metal parts. Among wooden parts, fasteners such as dowels, dowels, wedges and dowels can be distinguished. All of these types are made from hardwoods that have been dried over time.

Nagels

Nagels are wooden nails made of hardwood. Most often, pins are used to strengthen joints in window frames and greenhouse frames, when attaching parts for a frame under a mirror. Before hammering the dowel into the wood, you will need to drill a hole of a suitable size in the array, making it a little deeper than the length of the wooden nail. Then, so that the wood does not crack after driving the nail, the dowel is cleaned and rounded from all sides. After that, you can set the nail to the clearance of the hole, put a plank on it and hammer the nail with a hammer. The plank is needed so that the dowel does not crack or split during driving.

Dowels

Dowels are most often used to secure rafters to the roof ridge. Unlike pins, which are predominantly round, dowels can be round, cylindrical, square or rectangular. For greater convenience, in the process of penetration of the dowel into the hole, its end is always made pointed. In addition, so that the dowel does not fly out later, it is hammered with some tension. To do this, the diameter of the hole for it is always made smaller than the dowel itself. Most often, the dowel fastening is additionally reinforced with the use of glue.

Wedges

Wedges are used in joinery and carpentry quite widely than the above fasteners. It is an indispensable part of fastening designs. hand tool, tension structures, structures for strengthening and leveling walls, floors and roofs. By shape, the wedges are divided into 2 parts: one has only 1 side hewn, the other part has 2 hewn. Most often, coniferous wood is used to make wedges.

Dowels

Dowels can be either wooden or metal. But all of them are different inserts in the nests between two beams and are designed to increase their strength. Such fastening is additionally provided with steel bolts, which can pass both through the key and not touch it, compressing only the beams.

wooden dowels. Depending on what part of the tree trunk was used in the manufacture of the dowel, longitudinal, transverse, longitudinal oblique and stretch dowels are distinguished. The resistance across the fibers is much less than along them, so cross keys are not very popular. They are called transverse due to the fact that the direction of the fibers of the key is perpendicular to the direction of the fibers of both beams. Longitudinal keys provide stronger fastening. The direction of the fibers of the key here completely coincides with the direction of the fibers of the beams. Longitudinal oblique keys require a certain accuracy of the socket. Most often they are located at an angle of 45 °. They provide even greater strength to the beam, preventing it from bending in 2 directions at once: along and across. Tension keys are used where it is necessary to strengthen the beam and increase the internal tension at the same time. To do this, 2 wedge-shaped dowels are driven into the nest between the beams at once. Both keys must be fully driven in.

metal dowels can be recessed and pressed in, ring-shaped or square. Recessed dowels are used for side fastening of several parts. For the dowel, the nest is necessarily hollowed out, then the dowel itself is installed, and then the whole structure is tightened with bolts. A nest is also prepared for pressed-in dowels, they are fixed and then closed with the other half of the structure. Also, the connection is fixed with bolts.

Nails

In joinery and carpentry, nails are a convenient, simple, and common metal fastener. Depending on the thickness of the planks to be joined, nails of a certain thickness and length are used. The thicker and longer the nail, the stronger it will hold in solid wood. But this does not mean that all planks need to be nailed only with thick and long nails. A thin and narrow plank from such a nail can simply split into two halves. This effect can also be achieved by driving a nail into the end surface of the bar, and here there is still a possibility of the nail falling out of the hole formed. This is explained by the fact that the nail is driven not across the fibers, but along them. With shrinkage, the tension here will significantly weaken, cracks will appear.

The number of nails (the totality of their length and diameter) is always chosen depending on the thickness of the plank - the length of the nail itself must be at least 3 mm more than the thickness of the plank so that it can be attached to the base. Before nailing the plank to the base, make a few marks on the surface of the board. So you can evenly, beautifully, accurately and economically drive in each nail. But only at the same time they do not place the nails too close to each other - it is enough to nail the board in 2-4 places so that it holds firmly. In addition, you need to try to arrange the nails so as to prevent possible warping and bending. Another important rule is not to drive nails close to the end side of the plank: here the wood is most weakened, and a crack that goes from the end will split the entire board or split several centimeters of the board.

To make the fastening the most durable, you need to put a thin board on a thick board, but not vice versa. In addition, the connection will be even stronger if you drive the nail at a slight angle, and not exactly perpendicular. Sometimes it happens that a nail head will only spoil the appearance of the surface. To make the hat not visible, you can do the following: drive a nail 3/4 of its entire length, then bite off the hat with pliers and drive the rest into the array. The same effect can be achieved if you first flatten the hat, and then drive in a nail and straighten the remnants of the hat in the direction of the fibers. Then such a surface must be puttied in order to close up the resulting recess.

If, after hammering in the nail, its sharp end came out, the end must be bent, and then driven into the array. In some cases, it is necessary to kill a nail that has entered the wood up to the very head. To do this, you need to knock it out from the back if it came out, or cut the wood from the outside, then pry off the hat with pliers or a hammer, put a plank under the resulting gap and pull out the nail with either pliers or a nail puller. A plank will be needed in order not to crush the wood near the hat.

screws

Using screws when fastening parts, they get better and secure fastening. Most often, screws are used to fasten door and window hinges, handles, glazing beads, linings. When fastening with a screw, the integrity of the inner layers of wood is practically not violated, they do not shift, as with nailing. This is primarily due to the fact that the screw is screwed in and not hammered. As with driving in a nail, you need to choose the correct diameter and length of the screw. The screw should be 3-4 mm larger than the thickness of the attached plank so that it can adhere well to the base.

The number of the screw (the ratio of its length and thickness) is selected for a certain type of plank. For the thinnest plank, a screw 6 mm long is selected, while a thick plank is fastened with a 12-15 cm screw. Also, depending on the purpose of the screw, its cap can be hidden or convex. The first type of cap is designed for fixing furniture parts with subsequent putty. Such screws should not be visible on the surface. The second type of screws is designed both for fixing parts and for decorating the surface.

Depending on the size of the screw, it is screwed in one of two ways. If the screw is small and the wood is soft, then you can limit yourself to only marking with an awl on the surface at the place of screwing. But if the screw is large or its diameter is too large, then drill a small hole at the attachment point, slightly smaller in depth and in diameter than the screw, so that it can hold well in the array. If 2 sufficiently thick strips are fixed with such a screw, then both parts will have to be drilled so that the wood does not crack when screwed in.

In order to hide the head of the screw in the array, you will need to make a small conical recess, screw the screw to the limit and putty. But in any case, regardless of the size of the screw, it is screwed in with a screwdriver with suitable size and type of canvas. The screwdriver is inserted into a slot - a small slot on the head of a cross-shaped or straight-shaped screw.

To facilitate the work when screwing in screws, you can use several already proven methods. If you have to screw a screw into an array of hardwood, then before starting work, it must be lubricated with laundry soap. In the event that paint is applied to the surface of the fastening or it is inside the product, then grease or ski wax can be used as a lubricant. If desired, the remaining small greasy marks can be removed with alcohol or other degreasing solution.

In the event that you have to work with a particle board, first drill a hole slightly smaller than a screw, then lubricate it with glue and insert a piece of plastic tube into it. Then, the prepared screw is screwed into the modified hole.

It often happens that the screw must be screwed into the end of the board or bar. But such a mount was never considered durable. In order to increase the strength of the fastening, you can use 2 tricks. The first is that the hole drilled for the screw must be impregnated with oil-based or alcohol-based wood varnish. The second way to strengthen the structure is to use a dowel, which is driven into the end of the bar, and a screw is already screwed into it.

In the course of work, it also happens that an already tightly screwed screw interferes with the connection of certain parts. The following few tricks will help to remove it. Using an adjustable wrench, a blade of a screwdriver is fixed between its frames, which is then installed in the slot of the screw. Then press the screwdriver a little and turn the wrench. Even the oldest screw should come out easily. Another way is to use a hammer. First, insert the tip of the screwdriver into the slot, grasp the handle of the screwdriver with your whole hand so that the top remains open, and, gently hitting the top with a hammer, turn the screwdriver synchronously. The following method will help replace a screw with a half-off decorative cap. To do this, you will need a wrench, a screwdriver and a thin small wooden plank. If the screw is screwed close to the edge, then you can simply use wrench. You will need to firmly clamp the remains of the surviving half and turn the key until the screw is completely unscrewed. If the screw is located in the middle of the part and it is impossible to use one wrench, they take a screwdriver, install it in place of the former slot and move the prepared plank as close as possible to it. This whole structure is fixed with a wrench. Then carefully turn the key and make sure that it does not break.

bolts

The main purpose of bolts is to connect logs, beams or thick boards in load-bearing structures. Depending on the thickness of the beams, their diameter can vary between 10-30 mm, and such fasteners can reach 70-90 cm in length. When choosing a bolt size, the width of the beam must be taken into account. In order to install the bolt into the log, you will need to drill a through hole slightly smaller than the diameter of the bolt. Then a washer is put on the selected bolt, which will prevent the bolt head from being pressed into the solid wood. Also, a lock nut is put on the bolt, which prevents loosening of the fastening. Such an assembled bolt can now be driven into an array. The protruding end of the bolt is also supplied with a washer and locknut. A nut is put on it, which tightens the entire structure to the limit.

Clamps

Also, for fastening 2 beams or thick boards, a fastener such as a clamp is used. It is known to many from plumbing, when it is necessary to temporarily close up a hole in water pipe before the locksmith arrives. Most often, stainless steel clamps are used to fasten load-bearing structures, which are strips 8-16 mm thick and 28-105 mm wide. Clamps are rectangular, square and round and are used depending on the shape of the parts to be joined. One half of the clamp is installed at the place of attachment of 2 or more boards or beams, on the other hand at the same level - the second part and tightened with bolts.

corners

Corners are metal strips of stainless steel with several holes for fastening. Such corners can be straight or combined, that is, in the middle there is another bar located at an angle of 45 °. Different thickness and width of the corners allows them to be used when attaching window frames, door panels, gates.

overlays

Overlays are applied at connections in an end face or at building. They are steel plates of various thicknesses, lengths and widths, depending on the build-up parts.

Construction staples

Construction brackets are used for fixing all kinds of wooden structures. Outwardly, they are p-shaped or s-shaped rods made of thick square or cylindrical steel, reaching a length of 45-55 cm. Different types of brackets are used for various types of connections. The most common are straight staples, the ends of which are directed in one direction. The best connection of the beams to each other can be achieved if you take an expanded bracket or an s-shaped one. The ends of such a bracket are parallel to each other. If it is necessary to secure the wooden joint as much as possible, then it is best to use a turned bracket, one end of which is bent at an angle of 45 °.

capercaillie

This type of attachment is somewhat reminiscent of the ends of the bracket. They are used when fixing window blocks and door frames in the openings. The length of capercaillie can vary from 10 to 12 cm.

Joining wooden parts with glue

It is almost impossible to do without glue when connecting parts. When gluing wood, you need to use glue, which should be either transparent or light, does not change the color of the wood, does not set too quickly, its excess is easily removed, and inside the seam it would help protect the wood from decay and the penetration of microorganisms inside. In addition, most adhesives are water repellent.

Adhesives

All adhesives can be divided into natural and synthetic. Depending on what ingredients are used in the preparation of natural glue, they are animal, vegetable and mineral. In the manufacture of synthetic adhesives, only artificially created compounds are used. Any adhesive that is required for work consists of several components: the adhesive itself, a solvent that maintains a certain consistency of the composition, a hardener that helps it to set and connect parts, and antiseptics that protect the treated surface from insects, microorganisms and various substances destroying the wood structure.

Among the natural glues, the most commonly used are bone glues, prepared on the basis of bone meal. But such adhesives do not react well to moisture, and therefore, if, for example, it is planned to arrange a shower or a bathroom in the attic, it is better to take another glue for gluing. Casein glues are made from milk protein. They bond surfaces very strongly, but alkali is used as a solvent, which stains the wood.

K-17 glue is convenient for clean gluing large surfaces, it forms a thin film and does not harden for a long time. PVA glue, or polyvinyl acetate dispersion, sets quickly and therefore requires speed in work. It is a white liquid that becomes a transparent film after drying. This glue is the most versatile when gluing parts. Wood glue can be used several times. To do this, you just need to heat it on fire.

Both carpentry and bone glue are sold in granules or shavings, which turn into a sticky mass at home. If you bought glue in the form of chips or granules, then you can immediately pour it into hot water and, stirring, bring over low heat until completely dissolved. If the glue is in the form of tiles, then before being lowered into water, it is crushed, then poured into containers cold water and leave for a day until it swells completely. And only then they transfer the pieces to another dish and proceed to the gluing procedure itself. The finished glue should drain from the stick, which is used when stirring, it should be thick and resemble fatty sour cream in consistency.

In order to prepare glue, you will need to purchase a special device - glue stick. It can be replaced with 2 ordinary pans, and one of them should be slightly smaller so that it can be easily attached to the sides of the other with handles. Water is poured into a smaller saucepan and glue is poured, and water is poured into another so that the glue being prepared does not burn. If foam forms during the preparation of the glue, then it must be periodically removed. Most adhesives do not last long and smell rotten the next day at room temperature. In order for the glue to stand for several days, when preparing it, you can add a few grams of phenol at the rate of 1 g per 1 liter of glue. Now the prepared glue can be applied to the surface of the part. This will require either a bristle brush or linden bark, a piece of which is pre-soaked. In any case, the adhesive is applied to the surface in a thin layer.

Gluing

There are 2 ways to connect parts with glue: gluing or gluing. Gluing is used for various joints on the spike and on the mustache. Gluing is used only in the manufacture of plywood, when finishing the surface with veneer, etc. There are 2 ways to glue the parts: by squeezing the surfaces with clamps or by rubbing the surfaces together after applying glue to them. Lapping connects mainly thin parts, which, after a slight setting, are adjusted to each other and left until the glue dries completely.

This method of adhesive bonding of parts must occur quickly and clearly, therefore, before proceeding with its implementation, prepare everything necessary for work: clamps, gaskets, tapes, supports, belts, as well as the surfaces of the parts to be glued, which must be clean. In case it was accidentally soiled dirty hands or dripped oil, wipe the places of contamination with acetone or alcohol. Bonding pads are used to distribute the compressive force as evenly as possible. It also protects surfaces from dents when clamped with clamps. The gasket is always made slightly larger than the dimensions of the parts to be glued. Most often, gaskets are made from plywood sheets.

In addition, to avoid sticking surfaces to the gaskets, you will need to put more sheets of paper between the gasket and the surface. When gluing by compression, be sure to ensure that when installing the clamps there is no displacement of the surfaces, which then can no longer be restored. To make the seam good, durable, it is best to work in a room where the temperature does not fall below 20 °. Also, the glue must be applied in a thin, even layer, while the glue should not be too liquid. But a thick layer is also unacceptable - when it dries, it will crack.

It is also not recommended to grind the surfaces to be glued - the planes should be slightly rough, which will allow you to get reliable connection. If you need to glue several parts at once, you can’t apply glue to everything at once - in the lower layers the glue will begin to set, but will not be evenly distributed, this will make the surface look like waves. To prevent this from happening, the parts are divided into several parts, the planks of the parts are glued together, and then the parts. It is best to glue the levels, for example, in one step - the legs of the chairs, in the other - the seats.

If you have to glue complex structure, consisting of many nodes, then first they connect all the parts without glue, adjust if something protrudes, and only then apply glue. Obvious defects during gluing cannot be eliminated, and it is also impossible to disassemble an already glued structure without damaging it. After the glue has been applied to the nodes of the structure, it is necessary to put it under a press and hold it for a certain time so that the glue completely sets and dries. If carpenter's glue was used, then it is possible to remove the part from under the press only after 1 day. PVA glue requires less time - only 4-5 hours. But this does not mean that the glue is completely dry and the structure is ready for further work. After the required time has elapsed, loosen the clamps, check for layer shifts, and put it still for 1 day so that the glue dries completely.

Sticking

Sticking differs from gluing in that only facing work is performed here. This is a fairly simple way to imitate solid woods using only veneer and a wooden base. In addition, this technique will also help in the manufacture of mosaics, which will perfectly decorate the top of any table, wardrobe doors, bedside table in the bedroom, etc. Although precious wood veneer is used here, and the work itself requires care and accuracy of the eye, this work can perform even a person who has never dealt with a tree. It is more like an application made of paper and cardboard. But there are several features that must always be remembered and observed during work.

1. Glue the veneer only on a very flat surface, slightly rough, but without visible notches. If I may say so, the surface of the base should be velvet.
2. The veneer must be glued across the direction of the fibers of the base, but not along, otherwise cracks may appear that will only spoil the surface. They arise due to different shrinkage of the veneer and the base.
3. If expensive veneer is used and glued to a chipboard, then an intermediate layer of cheap veneer or cotton fabric must be glued.
4. Using veneer from burl or wood with a high graininess, the base is selected from carefully dried wood so that cracks do not form later.
5. For gluing veneer on small surfaces, PVA glue is used, and on large surfaces, wood glue is used. This will help improve the adhesion.

As well as gluing, gluing is carried out in 2 ways: by pressing and lapping. Both methods are performed in the following sequence:

• first, a layer of glue is applied to the base, then veneer is applied to it, ironed with a clean cloth, thereby removing all air bubbles from under it. After that, for a better connection, the veneer is moistened on top with a sponge with warm water. After 1-2 hours, when the glue begins to thicken, the veneer is smoothed with lapping in the direction of the fibers, trying not to pick up the edges. To do this, all movements must be directed towards the edges or diagonally to them;
• before leaving the structure until it is completely glued, you need to put sheets of white paper on the seams. Now all this can be left as it is, or you can put it under a press, laying paper on top of the veneer, then a gasket, and only then clamp it with clamps;
• screened and heated sand can be used as a press for parts with an uneven curved surface. First, a sheet of paper is placed on the surface, thereby protecting the veneer from contamination, and then a canvas bag with sand. The more sand, the more pressure will be exerted. But it should not be excessive so that the veneer does not deform. The optimal pressure will be exerted by a layer of sand of 9-11 cm. It is possible to release the surface from such a press only after the sand has completely cooled so that the veneer does not “bubble”.

When applying veneer to the base, some imperfections may appear. First of all, this is the formation of so-called siskins - places where the glue layer was insufficient and air cushions formed. The simplest tapping will help to find such areas - empty places will sound muffled under blows. Chizh should be cut with a joint knife, then carefully lift one edge and pour a few drops of glue into the void with a pipette or syringe with a needle with a large clearance. After that, with a rag, stroking the surface in a circular motion, distribute the glue inside the former siskin and iron the seam, which then needs to be applied with a paper strip. Then this place must be ironed with an iron heated to a temperature of 100-110 ° C (number "1" on the temperature controller).

Air bubbles formed due to uneven grinding most often have a convex shape. Such a bubble also needs to be cut, soak the veneer around the bubble a little, then pour a few drops of glue from a pipette or syringe and rub it with a warm iron through the paper. Some veneer parts can move when glued. Thus, millimeters of excess veneer appear at the edges. Only after the glue is completely fixed, they will have to be leveled. Depending on the size of the protruding edges, either a joint knife or a planer is used. The planer is suitable only for a relatively small protrusion - about 1 mm. The larger protrusion is removed with a joint knife. At the same time, a bar of the same thickness must be placed next to the part so that the veneer does not break off during alignment.

Since ancient times, after mastering the tools of labor, a person began to build a dwelling made of wood. Having gone through evolution, a person continues to improve the construction of his home for thousands of years. Of course modern technologies simplified construction, gave a wide opportunity for imagination, but basic knowledge about the properties of wooden structures pass from generation to generation. Consider ways to connect wooden parts.

Consider the ways of connecting wooden parts that beginner craftsmen face. These are mainly carpentry joints passed down from generation to generation, these skills have been used for more than one century. Before joining wood, we assume that the wood has already been processed and is ready for use.

The first basic rule that should be followed when joining wooden parts is that a thin part is attached to a thicker one.

The most common ways of joining wood, which will be needed in the construction of household buildings, are of several types.

End connection

This is one of the most simple ways connections (rallying). With this method, it is necessary to fit the surfaces of the two elements to be joined as closely as possible. The parts are pressed tightly against each other and fastened with nails or screws.

The method is simple, but to obtain the quality of the product, several conditions must be met:

The length of the nails should be such that, having passed through the entire thickness of the first workpiece, they would enter with their sharp end into the base of another part to a depth equal to at least ⅓ of the length of the nail;

Nails should not be located on the same line, and their number should be at least two. That is, one of the nails is displaced from the center line upwards, and the second, on the contrary, downwards;

The thickness of the nails should be such that when they are hammered into the wood, a crack does not appear. Pre-drilling holes will help to avoid cracks in the wood, and the diameter of the drill should be equal to 0.7 of the diameter of the nails;

For getting best quality pre-lubricate the joints, the surfaces to be joined with glue, and it is better to use a moisture-resistant glue, such as epoxy.

Invoice connection

With this method, two parts are superimposed one on top of the other and fastened with nails, screws or bolts. Wooden blanks, with this method of connection, can be placed in one line or shifted at a certain angle relative to each other. In order for the angle of connection of the workpieces to be rigid, it is necessary to fasten the parts with at least four nails or screws in two rows of two pieces in a row.

If you fasten with only two nails, screws or bolts, then they should be placed diagonally. If the nails will have a through exit through both parts, followed by bending of the protruding ends - this connection method will significantly increase strength. The connection to the invoice does not require a high qualification of the master.

Half tree connection

This method is more complex, it requires already certain skills and a more scrupulous approach to work. For such a connection, in both wooden blanks make a sample of wood to a depth equal to half their thickness, and a width equal to the width of the parts to be joined.

You can connect parts in half a tree at different angles.

It is important to observe the following rule:

So that the sampling angle on both parts is equal, and the width of both samples strictly corresponds to the width of the part. Under these conditions, the parts fit snugly against each other, and their edges will be placed in the same plane. The connection is fastened with nails, screws or bolts, and glue is still used to enhance strength. If necessary, such a connection may be partial. That is, the end of one of the workpieces is cut at a certain angle, and the corresponding sample is made in the other part. Such a connection is used for angular rallying. Both spikes (samples) in this case are cut at an angle of 45 degrees, and the joint between them is located diagonally.

Splicing to length

Such splicing of bars and beams along the length has its own characteristics.

For vertical supports, splicing is simple.

But it’s a completely different matter when a beam or beam at the splicing point is subject to bending or torsion loads, in which case you can’t get by with simple fastening with nails or screws.

The parts to be joined are cut at an angle (into an oblique overlay) and compressed with bolts. The number of bolts depends on the applied loads, but there must be at least two.

Sometimes additional overlays are installed, for example, metal plates, it is better on both sides, top and bottom, for strength, you can additionally fasten with wire.

Cleat

Such a connection is used when laying the floor or for sheathing boards. To do this, a spike is made in the face of one board, and a groove in the other.

With this splicing, gaps between the boards are excluded, and the sheathing itself acquires beautiful view. Appropriately processed lumber enters the distribution network, where they can be purchased ready-made.

Examples of such materials are batten or lining.

Connector "socket-thorn"

This is one of the most common joints of wooden parts.

Such a connection will provide a strong, rigid and neat rallying.

It goes without saying that it requires certain skills and accuracy in work from the performer.

When making this connection, you need to remember that a poor-quality spiked connection will not add reliability and will not have a beautiful appearance.

A spike connection consists of a groove hollowed out or drilled in one of the wooden parts, as well as a spike made at the end of another attached element.

The parts must have the same thickness, but if the thickness is different, then the socket is made in the thicker part, and the spike is made in the second, thinner part. The connection is carried out on glue with additional fastening with nails, screws. When driving a screw, remember that pre-drilling will facilitate this process. It is better to hide the head of the screw, and the pilot hole should be ⅔ of the diameter of the screw and be 6 mm less than its length.

One of the very important conditions is the same humidity of the parts to be joined. If the connected elements have different humidity, then when dry, the spike will decrease in size, which will lead to the destruction of the entire connection. That is why the parts to be joined must have the same humidity, close to the operating conditions. For outdoor structures, humidity should be in the range of 30-25%.

The use of wood to decorate buildings.

Choice of wood.

In carving, to perform large crafts with large elements, they often use coniferous wood as the main one. They are available, and the striped texture can be used in ornaments.

As background for invoice and slotted thread, used fir.

The valuable material is cedar, its soft, with a beautiful texture and a pleasant yellow-pink or light pink color of the wood core. The wood is easy to cut, cracks little during shrinkage and is resistant to decay.

Wood pears used for highly artistic carving details, as it is durable and warps little from atmospheric influences.

Poplar, the wood is very soft and light - used to make carved decorative column or background shields for fastening the overhead thread.

It is good to use wood to make chains from round rings. apple trees. This wood is used in small crafts, in applied carvings. In this case, the springy properties of the apple tree are used.

Wood is also used lindens. Very light, well planed, well drilled and polished.

carving from oak difficult to manufacture due to its hardness.

But oak is not afraid of moisture, it does not warp. Products from natural wood very beautiful, but too expensive. Veneering is used to reduce the cost of the product. For example, veneered doors are made, by order of the client, "under the oak". We get beautiful doors, outwardly similar to natural ones, but at a much lower price.

The rafter system is the most complex and one of the most critical elements of the house; the comfort and operating time of the building largely depend on the correctness of its construction. Calculation and design truss system should only be done by experienced builders or engineers with special training.

Designing a wooden truss system is much more difficult than any metal constructions. Why? In nature, there are no two boards with absolutely the same indicators strength, this parameter is influenced by a lot of factors.

The metal has the same properties, which depend only on the steel grade. The calculations will be accurate, the error is minimal. With a tree, everything is much more complicated. In order to minimize the risks of destruction of the system, it is necessary to give a large margin of safety. Most decisions are made directly by the builders on site after assessing the condition of the lumber and taking into account the design features. Practical experience is very important.

Why you need to splice rafters

There are several reasons why splicing rafters is required.

1. Roof length exceeds standard lumber length. The standard length of the boards does not exceed six meters. If the slope is large, then the boards will have to be lengthened.
2. During construction remains a lot good boards 3–4 m long. To lower the estimated cost of the building and reduce the amount of non-productive waste, these pieces can be used for the manufacture of rafters, having previously spliced ​​them.

Important. It must be remembered that the strength of spliced ​​rafters is always lower than that of whole ones. It is necessary to try to ensure that the splicing point is located as close as possible to the vertical stops.

Splicing methods

There are several ways to splice, there is definitely no better or worse. Masters make decisions based on their skills and the specific location of the joint.

Table. Methods for splicing rafters.

splicing method	Brief description of technology
	It is used on boards with a thickness of at least 35 mm. Quite a complex method, requires practical experience in carpentry. In terms of strength, the connection is the weakest of all existing ones. Advantage - saving lumber. Practically at construction sites it is used very rarely.
	The length of the rafter legs is increased with the help of an overlay. The lining can be wooden or metal. If the length of the two segments of the boards is insufficient in terms of the parameters of the truss system, then this method allows them to be increased. Butt joint has the most high performance bending strength, widely used during the construction of various structures.
	Overlap. Two boards are fixed with an overlap. The simplest method, in terms of strength, occupies a middle position. The disadvantage is that the total length of the two boards must be greater than the design length of the rafter leg.

In this article, we will look at two of the simplest and most reliable splicing methods: butt and overlap. It makes no sense to touch the oblique cut, it is almost never used due to a large number shortcomings.

Requirements of building codes and rules for splicing rafters

Inept splicing of rafters along the length can not only dramatically reduce their resistance to bending loads, but also cause complete destruction of the structure. The consequences of this situation are very sad. Building regulations provide for certain patterns during the selection of fastener sizes, places for its installation and the length of the overlays. The data are taken taking into account many years of practical experience.

Spliced ​​rafters will be much stronger if metal studs rather than nails are used to connect them. The instruction will help to make an independent calculation of the connection. The advantage of the method is its versatility, it can be used to solve problems not only with lengthening the rafters, but also with building up other roof elements. Specialized companies performed rough calculations and collected data in a table, but it only indicates the minimum acceptable parameters.

1. Stud diameter and length. In all cases, the diameter of the studs must be ≥ 8 mm. Thinner ones do not have sufficient strength, it is not recommended to use them. Why? In metal joints, the diameter of the studs is calculated for tensile forces. During contraction, the metal surfaces are pressed together so strongly that they are held by friction. In wooden structures, the stud works in bending. Separate boards cannot be pulled together with great effort, the washers fall into the board. In addition, during changes in relative humidity, the boards change thickness, thereby reducing the tightening force. Studs working in bending must have big size. The specific diameter of the stud must be determined by the formula dw = 0.25×S, where S is the thickness of the board. For example, for a board with a thickness of 40 mm, the diameter of the stud should be 10 mm. Although this is all rather relative, you need to keep in mind the specific loads, and they depend on many factors.

   

2. Board overlap length. This parameter should always be four times the width of the boards. If the width of the rafters is 30 cm, then the length of the overlap cannot be less than 1.2 m. We have already mentioned that the specific decision is made by the master, taking into account the condition of the lumber, the angle of the rafters, the distance between them, the weight roofing materials and climatic zone of the building location. All these parameters provide big influence on the stability of the truss system.

   

3. Distance between stud holes. Fasteners are recommended to be fixed at a distance of at least seven diameters of the studs, from the edge of the board the distance should be at least three diameters. These are the minimum figures, in practice it is recommended to increase them. But it all depends on the width of the board. It is impossible to reduce the distance between the rows of studs too much by increasing the distance from the edge.

   

   

4. Number of tie rods. There are quite complex formulas but they are not used in practice. Masters install two rows of studs, taking into account the distance between them, the holes are staggered.

Practical advice. To increase the bending strength of the spliced ​​rafter, the holes of the studs should not be located on the same line, they must be displaced by at least one diameter.

Splicing butt boards

Work is much more convenient to do on the ground, prepare a flat area. Put the bars on the ground - the rafters will have to be cut, you need a clearance for circular saw. Before splicing, find out exactly the length of the rafters. You need to measure it on the building, use any thin long boards, rope or construction tape. If there is an error of a few centimeters - not a problem. During the connection of the rafter legs on the roof, this error is eliminated without problems.

Step 1. Lay one board on the bars, cut the end exactly at a right angle. It is better to cut off with a manual electric circular saw.

Important. Follow the safety rules, this is a high-speed and very traumatic tool. Never dismantle the factory protection of the saw blade, do not turn off the electrical overload relays.

The rafter boards are quite heavy, while cutting, give them such a position that they do not pinch the saw blade or break prematurely during recutting. Prepare the second board in the same way. Make sure that the cut is only at a right angle. The ends of the spliced ​​boards should fit snugly against each other over the entire surface, this is necessary to increase the strength of the spliced ​​rafters. The fact is that even with the weakening of the connection of the studs, the ends during bending will rest against each other along the entire length of the cut and hold the load. Studs and overhead boards will only keep the structure from spreading along the length.

Step 2 Place two prepared rafter boards side by side. Prepare the board for the overlay. We have already mentioned that its length should be about four times the width of the board. If the roof slopes have a slight slope, the distance between the rafters is large, and the roof will be insulated mineral wool, then the bending loads increase significantly. Accordingly, the length of the splicing board must be increased.

Step 3 Lay the overlay on two side by side splicing boards. Quite often, the thickness and width of the boards, even from the same batch, differ by several millimeters. If you have such a case, then level the boards on the side to which the crate will be nailed.

Practical advice. The science of the strength of materials says that the thinner the material, the greater its resistance to bending along a thin plane. This means that, for example, five boards placed side by side on an edge with a thickness of 1 cm each withstand a significantly greater load than one board 5 cm thick. Conclusion - it is not necessary to cut thick expensive materials for splicing, you can use several thin pieces of the desired length. There are enough such pieces at any construction site.

Step 4 In a checkerboard pattern and at standardized distances, drill holes for the studs. In order to prevent the individual elements from moving during drilling, they must be temporarily fixed together. Use long and thin self-tapping screws for this purpose; it is not recommended to hammer with nails. They cut or tear the fibers of the wood, the strength of the board is slightly reduced. Self-tapping screws do not cut the fibers, but push them apart, after unscrewing the boards, they almost completely restore their original strength characteristics.

Step 5 Drill holes, do not place them in one line, otherwise the boards may crack during operation.

You can find recommendations after drilling holes to separate the boards and lay jute between them to prevent the appearance of cold bridges. This is not only vain work, but also harmful. Why? Firstly, no cold bridges appear at the splicing points; on the contrary, they have the largest thickness and, accordingly, the lowest thermal conductivity. But even if they appear, there will be no negative consequences, this is a roof truss system, and not a room window or door. Secondly, jute reduces the friction force between the splicing elements, and this has a very negative effect on their strength. Thirdly, if condensate gets on the material, which is very likely, then moisture will be removed from it for a very long time. There is no need to tell what consequences the prolonged contact of wooden structures with moisture leads to.

Step 6 Insert the studs into the prepared holes, put washers on both sides and tighten them firmly with nuts. It is recommended to tighten until the washers are pressed into the tree. The excess length of the studs can be cut off with a circular grinder with a metal disc.

All other rafters are spliced ​​in the same way.

Overlap splicing

This connection is easier to make, but under one condition - the total length of the two boards allows, it must be greater than the length of the rafter leg by the amount of overlap.

If you have low quality lumber, then before starting work it is recommended to decompose them into flat surface and make a revision. For long sections of spliced ​​rafters, choose straight ones, and for segments, use curves. Although for the truss system it is highly recommended to buy only quality materials, this is not the architectural element of the building on which you can save.

Step 1. Select boards and place them on top of the raised beams. If you wish, you can align the ends with circular saw, there is no desire - do not equalize. The condition of the ends does not affect the strength of the overlap splicing.

Step 2 Lay the boards on top of each other, adjust the length of the joint and the overall size of the rafter.

Practical advice. Boards should lie on top of each other strictly parallel. Due to the fact that the upper one rises above the lower one by the thickness of the material, it is necessary to place stands from segments under it and the bars. The thickness of the segments should be equal to the thickness of the bottom board.

Step 3 Align the boards on one of the edges and temporarily fasten them with self-tapping screws. Drill holes, install studs, washers and tighten nuts.

Butt splicing with plywood

One of the ways to splice rafters helps to save boards and rationally use the waste of various lumber. In this case, cut plywood sheets with a thickness of one centimeter are used.

Step 1. Lay the rafter boards evenly on the site, close the ends, pay attention to the parallelism of the side faces. The boards must be extremely uniform in thickness, the ends are cut exactly at a right angle.

Step 2 With a brush, generously smear the surface with PVA glue.

Step 3 Lay the prepared piece of plywood on the splicing site, press it firmly with clamps. During fixing, make sure that the plywood does not move from its original place.

Step 4 Fasten the plywood to the boards with long, strong self-tapping screws in a checkerboard pattern. The length of the self-tapping screws should be 1–2 shorter than the total thickness of the boards and plywood, their ends cannot come out from the back. Be sure to put washers under the screws large diameter. Before tightening the screws, drill holes in the rafter. Their diameter should be 2–3 mm less than the diameter of the threaded part of the hardware.

Step 5 Turn the board upside down, put it under the ends of the stand, they should not hang in the air. Carefully remove all installed clamps one by one.

Step 6 Spread the surfaces with glue and place a second piece of plywood on them. Clamp it again with clamps.

Step 7 Tighten the screws with great force.

Important. When tightening the screws, pay attention that they are not located against each other. The offset must be at least three centimeters.

Step 8 Remove clamps. To strengthen the splice knot, tighten it with through pins. They should be placed in the same way as with ordinary butt splicing.

Practical advice. Holes for studs should be 0.5–1.0 mm smaller than the diameter of the stud. There are times when it is impossible to accurately select the diameter of a drill for wood. Then it is recommended to use a slightly smaller diameter drill, let the stud come in with a sufficiently large force.

During its clogging from strong blows of the hammer, the first few turns of the thread are crushed, which makes it very difficult to wind the nut. To avoid problems, start the nuts before driving the stud, now let the thread on the end be jammed, it is no longer needed. Before installing the rafter in place, check that the glue has dried. In good weather, it takes about 24 hours for it to solidify completely.

The final touch - applying glue

Important. If, during the splicing of the rafters along the length of the boards, the nuts were twisted until the washer was sunk into the wood, then this cannot be done with plywood. Carefully control the pressing force, do not damage the plywood veneer.

How to properly hammer nails into the rafter when splicing

It is not always possible and necessary to splice individual elements of the rafters with the help of studs, sometimes it is easier to do this with ordinary smooth nails. But you need to be able to score them correctly, otherwise, over time, the compression force of the boards will decrease significantly. The length of the nail should be 2.5–3 cm greater than the thickness of the rafter at the junction.

How to properly drive in nails to connect loaded or critical wooden structures?

Step 1. At a slight angle, drive the nail into the boards, but not all the way. It is necessary that the tip protrudes from the back side by about one centimeter.

Step 2 On the reverse side of the rafter, bend the nail at a right angle with a hammer.

Step 3 Drive the nail in about one centimeter more. Bend the end again, the bend angle should already be much less than 90°. The more you bend it, the more secure the final fixation will be.

Step 4 Now you can drive the nail head to the very end. On the reverse side, bend the protruding part until the sharp end fully enters the board. Remember that the exit point of the nail body and the place where its point is driven in should not lie on the same line.

This technology completely eliminates the independent weakening of the pressing force.

It has already been mentioned that the bending strength of the rafter at the splicing point is always less than that of the whole element. If possible try to place this knot as close as possible to the ridge, mauerlat or various spacers. Such precautions minimize the risks of mechanical destruction of the rafter leg. If this is not possible for one reason or another, then it is not recommended to place the stop under the splice at a distance of more than 15% of the leg length from either end.

Never use black screws to connect. This metal has two significant drawbacks. First, it quickly oxidizes and loses its original strength. The second - the manufacturing technology of such self-tapping screws involves hardening. Hardened self-tapping screws, when the permissible load is exceeded, do not stretch, but burst. During the operation of the roof, the relative humidity of wooden structures changes, and the thickness of the boards fluctuates accordingly. And this can significantly increase the tensile force of the self-tapping screw, it will not withstand and will crack.

Do not overdo it with the number of hardware. If there are too many of them, then the holes will significantly reduce the strength of the parts to be joined, as a result you will get the opposite effect, the build-up will not increase, but weaken.

Video - Splicing rafters along the length