High-quality connection of the beams with each other during the construction of a house is of no small importance. The reliability of the entire structure and the preservation of heat in the house largely depend on the method and accuracy of the connection.
The quality of the connection of the beam depends on the strength and thermal insulation characteristics future design.
Construction wooden houses with new technologies for the manufacture of timber, it has become rapidly gaining popularity. Ecologically pure material with good thermal conductivity and attractive appearance, it is great for the construction of residential buildings and other buildings in any region of our country.
The most important stage in the construction of wooden houses is the articulation of the beams among themselves. Highly specialized equipment for the manufacture of studs and grooves is used only in large-scale production, due to the high cost and large size. However, the connections of the profiled timber can be done with your own hands.
Necessary tool for making joints
Figure 1. Types of timber connection.
At self-manufacturing connections, you can use the usual manual power tools available from the developer or specialists, such as:
- Chain saw with petrol or electric drive. An electrically powered hand-held circular saw can be used, but the maximum allowable cutting depth of the device must be more than half a tree.
- A set of chisels. It is not always possible to find a tool of the required length and strength in trading enterprises, so it is advisable to make it yourself or order it from a blacksmith.
- Hammer, mallet, axe.
In the old days, cutting corners was done with a single axe, but it took a lot of time. Modern instrument with various types of drive will greatly facilitate the work and reduce the time spent on work.
The main methods of joining timber when laying
At the junction, you need to choose a specific method that guarantees optimal strength and tightness of the joint. Corner joints can be made:
- with ends protruding beyond the main dimensions;
- without protrusions;
- butt-laying, when the bars do not overlap each other;
- T-connection for walls inside the building.
Figure 2. The device of a rectangular root tenon.
Residual method technology provides the best quality corner connection, but requires more material. On each beam, from 0.4 to 0.6 meters of irrationally used length is obtained. With a height of 15 crowns, the total unused length will be from 20 to 36 m. With a beam length of 4 m, this will be from 5 to 9 additional products. You can see the corner connection with protruding parts in fig. 1a.
The first crown in the building usually fits into the joint with the key groove with the specific name of the joint - "oblo". This method is used with any method of laying the material, with or without protrusions. Sampling is performed at half the thickness of the product. The articulation of the corners of the house without protrusions can be seen in Fig. 1b. To prevent displacement in the main planes, subsequent crowns must be joined according to the “radical spikes” type with the installation of dowels. The device of a rectangular root spike is shown in fig. 2.
Nagel is wooden beam OK round section 25 cm long and about 30 mm thick. In the beam laid on the cushioning material, it is necessary to drill a hole with a depth exceeding the length of the dowel by 20-40 mm, and hammer the part into it.
Corner butt joint is the most in a simple way. The quality of such joints is extremely low, to create warm corner this way is unrealistic. The fastening of the beam with such a docking is carried out with metal brackets with spikes, nailed. Laying the beam end-to-end is shown in Fig. 1c. How to fix the beam with a metal bracket can be seen in fig. 1e.
Figure 3. Dovetail.
T-shaped connection of capital and internal partitions has several options:
- joint using a key groove;
- joint "groove-thorn" in the form of a symmetrical trapezoid;
- joint "groove-thorn" in the form of an asymmetric trapezoid with a right angle;
- the use of a groove-thorn joint of a rectangular shape.
Spikes in the form of trapeziums are designed to maintain the connection during loosening of the structure and efforts aimed at pulling apart in different directions. The device of such joints is a complex, but also more reliable fastening. Because of appearance connection was named dovetail". The arrangement of such a joint can be seen in Fig. 3. Making a dovetail requires care and patience when fitting surfaces.
It is possible to assemble and disassemble the connection only by moving the products in a vertical plane.
Many craftsmen prefer to fasten walls with rectangular root spikes. Often, T-shaped joints are fastened with special brackets, long bolts with washers large diameter or nails. An example of a right angle stud connection is shown in fig. 1g
Longitudinal material connection
Figure 4. Butt and overlay connection.
One of the main disadvantages of timber is its length limitation. The standard dimensions of manufactured products are from 4 to 6 m. With long walls or when using trimmings, it is necessary to make a longitudinal connection. Such connections are undesirable in the construction of main walls due to possible deformation. If it is necessary to arrange longitudinal joints in several crowns, they cannot be placed in adjacent crowns along one vertical line. For internal walls there are no restrictions on timber splicing due to a more stable temperature regime.
When splicing the timber along the length, a central spike or various joints with a lock are used. Most often, a direct lock is used due to the simple manufacturing process. In the beam, samples are made in half the thickness of the beam. The resulting surfaces are available for processing and can be carefully adjusted.
A reliable connection of the beam to displacements can be obtained by using a central spike. The nest must be made a little more than the length of the spike. The length of the spike should be twice the width of the timber. To connect more firmly, you can install two spikes.
The lengthening of the beam can also be done overlay. The overlay connection can be oblique or straight. Connection types can be seen in Fig. 4. The ends of the products must be given the selected shape and laid in place. Subsequent crowns will compress and fix the connection with their weight. When extending the beam in the main walls, it is advisable to use a combination various mounts. The products fitted for the overlay connection must be additionally fixed with one or two wedges. A view of the wall with a spliced beam can be seen in Fig. 1d. Sealing material must be laid in all connections.
Production of corner joints of timber at an oblique angle
In building structures, there are always corner joints of timber, the size of which does not correspond to 90 °. On most buildings, such corners are located in the attic part of the room. Their size depends on the slope of the roof. On the main walls, angles of various sizes may occur when constructing protruding or recessed elements.
Articulation device under blunt or sharp corner it is desirable to perform according to the principle of "groove-spike". The protrusions and recesses are sawn at the required angle, their surfaces are adjusted accordingly. To increase the strength, you can use additional fastening with bolts, screws or nails of the required length. If the thickness of the products is large, you need to use metal brackets of the required shape with the appropriate fastening.
In the manufacture a large number identical joints, it is desirable to make special marking templates that will speed up and facilitate the process of marking for joining logs in a log house.
For templates, you can use tin, plywood, thick cardboard, thin plastic. When making joints, you should first make a cut in the desired position, then remove the areas inaccessible to the saw with a chisel.
Ready-made building projects offered by manufacturers of building materials are equipped with profiled timber with joints. All types of studs and grooves are selected based on the required strength and are made on industrial equipment with high precision.
Connecting a beam into half a tree or in another way during the construction process requires a responsible attitude. For wood, completely different types of fasteners can be used, the durability of which is due to the high strength of the material used. wooden buildings environmental friendliness, increased durability, as well as attractive appearance.
One of the most milestones the construction of wooden houses is the construction of a log house. Correct docking of the beam allows you to securely stack wood material connecting workpieces to each other. Lifetime wooden frame depends on the reliability of the product. This affects the soundproofing characteristics and the ability wooden walls retain heat.
Types of timber connection
The choice of method for splicing timber is influenced by the features of the structure and the type of material used. In this case, it can be used different types beam connections. Violation of technology in the process of building a log house often leads to a disastrous result.
Before making a connection with your own hands, you need to think about how to properly join the timber. If this is done incorrectly, then gaps will begin to appear in the building, and the building itself will begin to tilt. Finding a way out of this situation is not difficult, since you can connect the beam in several ways:
- Butt.
- On dowels.
- Half a tree.
- Dovetail.
- On root spikes.
You need to know all the basic techniques used in the construction of structures made of wood. Not all methods are overhead, they differ significantly from each other, therefore these technologies require a special approach.
Corner connection method
modern building wooden structures due to the use of two types of corner joints:
- No residue ("in the tooth", "in the paw").
- With the remainder (“into the bowl”, “into the oblo”).
The connection of the beam in the corners with the remainder suggests that the ends of the log house finished building will protrude beyond the boundaries of the wall by about 0.5 m. This construction method is more expensive, but it has a number of advantages:
- heat transfer decreases;
- increases the reliability of the structure.
Corner joints of timber
The use of the reception of the connection with the remainder "into the bowl" involves cutting out the lock grooves. Ways to connect the beam in the corners with the remainder are as follows:
- Unilateral.
- Bilateral.
- Quadrilateral.
This type of connection involves the creation of a notch, that is, a perpendicular groove on the upper side of the timber. Corner connection of this type of timber does not require significant effort and a lot of time.
The creation of a four-sided locking groove, which requires great skill and experience of carpenters, provides a fairly strong fastening. The groove is cut on each side of the product. The crowns are stacked like a designer. This technique provides greater strength to the frame.
Butt joint technique
Joining a beam in a butt way involves creating a connecting seam by attaching one beam to another with the ends. Each element on top is covered by the next product. To create a reliable connection, the ends of the products should be sawn off with an angle of 90 °.
Even if the butt joint is sufficiently tight, this does not guarantee that heat losses will not be too large. This is unprofitable, especially when building a bath from a bar. The “butt” connection method can be replaced by a more reliable method in the “radical spike”, which is also called the “warm corner”.
Butt joint
The joined beam is fixed with studded steel plates. They can be hammered with staples or nails. In order for the surface of the product to be perfectly flat, the carpenter must be able to adjust the ends of the joined beams. Due to the low tightness of the corner, periodic loads may occur.
Experienced builders do not recommend using the "butt" method, which is considered one of the fastest methods. Otherwise, the heat loss will be very large. This will not save time and effort for complex types connections. The method of joining the beam without residue "butt" is not suitable for all types of buildings.
Dowel connection
Laying timber, spliced using dowels, allows you to get a reliable and solid building from wood. To splice the beam at the corners, wedges are required, that is, dowels (dowels) made of hardwood. For timber, it is ideal to use a wooden dowel, for example, from aspen. The key, which falls into the sawn groove, connects the products very tightly.
Dowel connection
Wedges make it possible to achieve high strength of the log house and reduce its thermal conductivity. The elements are attached to the dowels driven into the connection, which is pre-sawn. The key may have different shape: prismatic, rectangular, dovetail, straight or notched.
When splicing beams that work in tension, cuts are used that preserve them from longitudinal displacement. This type of splicing is called a lock. In some cases, the cuts have to be strengthened with bolts or dowels, in this way they can be connected.
Products connected with keys must have grooves that are identical to the grooves of other elements. Dowels are wedges that connect two wooden element, pins are transverse, longitudinal and oblique. The use of the latter type of dowels is available only to professionals.
Assembling a log house according to the method in half a tree
An improved half-tree assembly method involves the use of a dowel. This allows you to increase the strength of the corner joint. The connection of the beam along the length is also possible by laying in half a tree. Strengthening of the entire structure is carried out using dowels.
An element connected to half a tree is sawn in half in width. Hence the name of the structure itself, since the size of the cutting is equal to half the section. Pre-drilled holes for the dowels in the product. The dowels must be inserted near the corner joints. The length of the dowel is calculated in such a way that it is enough for several products at once.
Joining a beam using the half-tree method
Corner connection is created by cutting at the top and bottom. This is how 2 links are processed. To ensure the greatest strength of the connection, wooden bushings are used, which are mounted at the ends of the cutting. The option of oblique felling is also acceptable for creating a reliable log house using the half-tree method.
This type of corner fastening is widely used in the construction of residential buildings. For example, in the process of erecting log cabins from profiled timber. All joints are carefully insulated. To reduce the blowing of the structure, the cutting is made with a slight slope, and not at a right angle.
Connection method in the "root spike"
Method corner assembly the "root tenon" is the simplest type of interlock. The method is used to obtain reliable fastening from spliced elements. The root spike is a structure that includes a spike and a rectangular groove. Their dimensions in height and width are 4 cm with a beam section of 150 mm. Cutting a spike and a groove is quite easy according to the scheme.
The method of connecting the beam with a root tenon
The root spike method is the most common. In one of the joined products, a special groove is made at the end. The end of the other is connected to the first beam with a vertical spike. All work should only be carried out by an experienced carpenter.
The laying of each subsequent crown is made using a wooden dowel, which has a round cross section. When laying the elements in the “radical spike”, it is necessary to use flax jute cloth to increase the density of the assembly and improve the thermal insulation of the log house.
If the logs are one-dimensional, then the layout can be simplified by making appropriate templates. It is possible to carry out a more thorough compaction of the cutting. To do this, you can use the assembly method in the “paw with a root spike”.
Dovetail connection
The structure of the assembly structure using the dovetail method resembles a root spike. The fastening method is used for corner joints, T-shaped and in length. When cutting a spike and a groove at the end of the product, identity must be observed. The tight connection knot is provided thanks to a trapezoid form of a thorn.
The method of connecting the beam "dovetail"
The T-shaped assembly structure is widely used in the construction of timber houses. Additional overlaps from the inner surfaces of the walls of the building are not required to be left. The dovetail technique allows the use of elements of a smaller section.
Insulation of corner elements during installation is carried out using jute fiber. However, the system is not permeable. Before dovetail installation corner fixings can be cut down in a way that is similar to the half-tree technique. The cutting should have a trapezoidal shape. Each product is stacked one on top of the other. Variety horizontal fastening corners using the "dovetail" method is the connection of the timber "in the paw". The product is sawn horizontally, which involves the creation of trapezoidal recesses, suitable friend to friend.
Mounting via longitudinal connection
To increase the insufficient length of the timber, carpenters recommend using the appropriate technique. It is not difficult to choose a method of longitudinal connection, since the following methods allow joining a beam:
- Half a tree.
- Spike with dowel.
- Root spike.
The ends of each product must be sawn, making grooves for joining the bars. The reliability of the assembly is ensured by the use of spikes with keys. Splicing of timber along the length is of high quality and reliable, it is carried out by analogy with the angular method, which allows to splice timber.
Ways of longitudinal connection of a beam
The lengthening of a beam by the method of a longitudinal root tenon is associated with cutting a groove at the end of one product, and a tenon on the other. The greatest fastening strength is achieved by giving the spike and groove trapezoidal shapes.
Any of the presented and outlined methods of erecting wooden buildings has its own characteristics. But there is general tips which are suitable for any assembly technique. The beam must be rounded off outer side to prevent stagnation of rain or melt water in the grooves. The contact points of the elements must be perfectly aligned and sanded. To provide additional density of the structure, it is possible to coat the joint with a mixture of resin and sand.
Watch the video for the topic of our article.
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 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 exactly the same strength indicators, 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 large stock by strength. 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.
- 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.
- 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. Enough complicated method requires hands-on carpentry experience. 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 highest bending strength, is 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. Disadvantage - the total length of the two boards must be greater than the design length 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 the large number of 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 not nails are used to connect them, but metal studs. 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.
- 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? AT metal connections 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.
- 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 climate zone building location. All these parameters have a great influence on the stability of the truss system.
- 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.
- Number of tie rods. There are quite complex formulas, but in practice they are not used. 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 thinner 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. To ensure that when drilling holes individual elements did not move, you need to temporarily fix them 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 most low thermal conductivity. But even if they appear, then no negative consequences will not, this is a roof truss system, not room window or a 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 place large washers under the screws. 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. Under small angle drive a nail into the boards, but not completely. 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 exceeding permissible load 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
Over the centuries, the use of wood in housing construction has accumulated vast experience in working with lumber. But today the material is very different from what it used to be. Products can be different not only by the type of wood, but also by its grade and processing method.
Methods for joining a beam in length
The standard length of a beam is 6 m. In the construction of walls exceeding this indicator, it is required to build it up, which is carried out by the ligation method, which excludes the location of joints on the same line. To do this, in the rows of bars, the connections are made alternately: either on one side of the house they will lay the missing segment, then on the other.
The crowns are built up using the “key groove” method, otherwise it is called “half-tree”. This is the easiest way to connect a beam and it is done by deepening one end into the thickness of the second. To do this, the corresponding sides of these elements are cut to ½ thickness. For greater certainty, the joints are fixed with studs or other fasteners.
More complex double-sided lock. It is a joining of lumber using the "groove to groove" method. To do this, cuts are made perpendicular to the cut plane at the ends of the joined bars. Each of the fastened elements must have its own groove and its own spike, but they must be located so that when the ends are connected, the protrusion of one enters the recess of the other, and vice versa. In this method of lengthening, it is very important to maintain the dimensions of the cuts, otherwise the strength of the joint will be doubtful.
Another way to connect lumber is a “deaf frying pan”. It is more often used in corner joints, but is also good for building in length. In order to fasten lumber with this method, a spike in the form of a triangle with a horizontally truncated top is cut out at one end of the beam, and a groove of a similar shape is cut at the second. Docking is done by applying a spike from above and driving it into the groove.
What is the most effective way to build a beam in length?
The most reliable connection is considered a four-sided groove. But it is very difficult to perform gashes, so it is rarely used in practice. It requires maximum accuracy in calculations, measurements, sawing. Therefore, such work is entrusted only to professionals. Previously, craftsmen could make these complex cuts with a single axe. Today, developers are armed with modern powerful tools, but not everyone is able to make this complex “lock”: skill in such work is still necessary.
Today, when choosing a material for the construction of private houses, developers are increasingly choosing wood. This choice is due to a number of positive qualities this building material. Wooden house is primarily environmental clean house. A wooden house can fit into any landscape, giving it a unique personality and a special atmosphere. To this it is worth adding affordable prices for wood and the relative ease of construction wooden house. And if we take into account the savings in time and money during its construction, then the choice of wood as a building material will be fully justified.
A house made of timber is environmentally friendly and harmoniously fits into any natural landscape, to which we should add the availability of material and the relative ease of construction.
Our ancestors over the centuries have accumulated vast experience in the construction of wooden houses. But today, more and more often, instead of a traditional log, a wooden beam is used. And although the technique of connecting the elements of a log and a beam has much in common, it is still somewhat different. Therefore, when building a house from a bar, you need to know how to join the bar, if the need arises.
The need for docking
Marking and calculations of some types of joints of beam corners.
Although the houses being built may differ in the type of wood and the way it is processed, the question of how to properly lay the timber and securely fasten it between the crowns will always be relevant. It is from these two factors that the life of the built house depends. After all, improper installation will lead to the fact that the house will gradually tilt to one side. And with a loose connection of the crowns, the walls will certainly freeze through in winter.
The need for joining the ends can arise in only two cases: when cutting a corner and when the length of the wall is more than 6 m ( standard size beam length). You can also add to them the cutting of internal walls during external walls house under construction, but in this case we are talking only about one end.
Since these are three completely different operations and they perform different tasks, the joining of the ends in each case is performed differently, although it has similar elements.
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Types of fastening the beam at the corners
Two types of fastening of the beams in the corners: a log house "in the paw" and a log house "in the oblo".
The stability of the whole house depends on the reliability of fixing the corners. There are two ways to join a beam at the corners - with the remainder, i.e. with protruding ends, and without residue. The main type of connection with the remainder is a type of docking "in oblo".
The main types of connection without residue: in the paw, with a key groove of the “in the oblo” type and T-shaped connections - a straight or lock groove and a trapezoidal tenon, rectangular or symmetrical.
The main advantage of the joint without residue is the saving of material. But on the other hand, a house where the ends in the corners are connected to the rest is more stable. In addition, it resists wind and rain better, it will be less swept up with snow in winter. And all taken together contributes to a more comfortable atmosphere inside the house. It is easier for a non-professional to make such a joint, therefore, if you do not have sufficient experience in building wooden houses, then it is better to choose this method for corner joints.
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Ways to connect corners with the remainder
Most often, for joining corners with the remainder, the “in oblo” type (into the bowl) is used. With this method, the bars are interconnected using locking grooves. Such grooves can be made single-line, double-sided and four-sided.
For the device of a single-line lock, a transverse notch is made at the junction at the end. The width of such a notch must exactly correspond to the cross section of the end. This method of corner connection is mainly used for profiled timber.
To make a double-sided lock, perpendicular cuts are made at the end on both sides for a quarter of its thickness. When assembling, the groove cuts join the groove. It is very important that the grooves match each other as closely as possible. A large mismatch in size will adversely affect the reliability of the connection as a whole. In addition, additional sealing of cracks is required.
If you need to join the beam at the corners as reliably as possible, use a four-sided lock. With it, cuts are made not from two, but from all four sides of the butt. If the grooves are made correctly, then the corner will be complex, like a designer. But you need to have a very high qualification to make them as accurate as possible.
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Ways to connect corners without residue
The simplest corner connection of this type is a butt joint. With this method, no cuts are needed - the bars are joined at the ends. The connection is fixed with metal plates using nails or staples. However, this method cannot guarantee sufficient tightness of the corners of the house, even with perfectly flat ends. Therefore, in the construction of residential buildings, it is practically not used.
Use for connecting the ends of special dowels made of hard rock tree allows you to make such connections much better. Special grooves are made in the end: in one beam, longitudinal at the very end, in the other, transverse not far from the end. When connecting, these grooves must match so that a key can be inserted into them. Without sufficient experience, it is better to stop at a perpendicular-parallel groove. For greater reliability, such grooves are made oblique by professionals.
Fastening with a root tenon is the most common type of corner assembly using a beam. A groove is made at the end of one of the bars, and the end of the other is sawn off, leaving a spike of the same size. When connecting, the spike enters the groove, thus fixing the connection. To make it even more reliable, not one, but several grooves and spikes are made at the ends.
Most secure fastening of this type - “dovetail”, when the spike at the end is not rectangular, but trapezoidal. Accordingly, a groove is made under this form at the end of the beam to be joined.
There are very important point which should not be forgotten. When using a tongue-to-groove fastening, in order to compensate for future shrinkage of the log house, it is necessary to leave vertical gaps between the groove and the tongue.
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Longitudinal beam connection
Longitudinal connection of the beam: a, c. half a tree; b, d. oblique cut. 1. Nagel. 2. Nest.
Since the standard length of the beam is 6 m, when building walls of greater length, it becomes necessary to join the beam along the length. When choosing docking methods, it is necessary to take into account what kind of force and type of deformation the docking site will be subjected to in the future. Without taking into account these factors, it is impossible to properly join the timber.
The most common methods of this type of connection are half a tree, a longitudinal tenon on a key, a longitudinal root tenon, and an oblique lock.
If a compression force acts on the docking site, a half-tree docking is used. To join the beam along the length in this way, a rectangular groove is made on each beam for half its thickness. The length of the groove should be 2 or 3 times the width of the beam.
Then the grooves overlap each other. Such a connection is very unstable, so it must be fastened with nails and additionally reinforced with dowels - rods made of hard wood. The main task of the dowels is to exclude the possibility of displacement of the connected ends. Holes are drilled in the beams with a diameter corresponding to the thickness of the dowels, into which they are then inserted.
If a tearing force acts on the wall, it is necessary to join the timber along the length with the help of locks. For this, grooves are also made at a right angle, but in a different way. Such a groove is 2 times the width of the beam, while from the end the groove is made 1/4 of its thickness, and then deepens to 1/2. The resulting ledges interlock with each other. For greater reliability, they also need to be additionally strengthened with nails and dowels or used for fastening bolts.
Longitudinal connection of the beam: a, c. direct padlock; b, d. oblique overhead lock.
If the wall of the house will experience a strong “bending” force, then increased strength will be needed for the connection. Here, for reliable fixation, “oblique locks” are needed. This is the most difficult longitudinal connection in terms of execution, but it significantly surpasses all other types in terms of reliability.
The execution technique is the same as with the arrangement of conventional locking joints, only the cuts are made not even, but oblique. When using this connection, it is extremely important to accurately observe the proportions of the fasteners, since the quality of the joints depends on their accuracy. If possible, the place of such a connection is additionally reinforced with 2 building brackets, stuffing them crosswise.
Despite this variety of species, there are general rule to be performed. To rainwater did not accumulate in the connecting grooves, on the outside of the wall the beam must be rounded off.
Also, regardless of the chosen docking method, it is desirable to treat the docking site with a special compound, a mixture of an epoxy wall and sand or sawdust. Joints treated in this way are more airtight, moreover, the resin glues the joined surfaces, giving them additional strength.
All these types of connections are described in detail in GOST 30974-2002. But this is not a dogma, but only recommendations. In the process of building a house from a bar, each developer must decide for himself which type of connection is suitable for his house in each case.
Good luck to you! Strong walls to your home!