Dowels for fastening timber are an indispensable component in the construction of wooden structures

Nowadays, wood is often used to create all kinds of structures. In most cases, profiled timber is used, which is well suited as a building material for the construction of houses and other buildings.

Wooden dowels began to be used in order to ensure reliability and strength when connecting building elements. Thus, the structure receives the necessary rigidity, and the likelihood of wood deformation fades into the background. In addition, there will be the possibility of normal shrinkage of the house. Correct installation will make it possible to combine all the elements without losing the required structural properties at home.

Wooden dowels for building a house made of timber Source es.decorexpro.com

Direct purpose of dowels

Dowels are peculiar pins, the installation of which is carried out perpendicular to the axis of the elements. They are used to connect adjacent crowns. The main task of timber dowels is to prevent the elements from moving. This is due to the fact that even dry elements of a wooden frame can be deformed during operation, which is caused by various factors, for example, humidity. The use of this component for fastening does not allow the possibility of wood deformation, because they tightly connect the crowns of the frame with each other.

You can hear many opinions that the dowel serves to tie the frame, but such a judgment is erroneous. This component is designed to ensure that when the timber shrinks and dries, it does not lose its original position, so that the structure of the building does not move.

Wooden dowel - reliability proven over centuries

What is a dowel in construction? What does Vladimir Dahl's explanatory dictionary tell us? A dowel is a wooden or metal rod that connects the heights of the crowns of a log house. This is a fastening element designed to prevent the movement of parts of wooden structures made of logs or timber.

According to another definition, a dowel is a wooden, metal or plastic, composite rod of cylindrical or other shape, used for fastening (joining) parts of wooden structures.

If you have heard the common expression Nagel for concrete, then keep in mind that we are talking about specific screws. They are called so because of slightly similar functions. This is where their similarities end...

Dowel and dowel: concept and features

Sometimes dowels are also called dowels, although this is not entirely correct. At least not correctly in all cases. Some builders generally call a round rod a dowel, and a square rod a dowel.

A dowel , according to the Great Soviet Encyclopedia, is a plug-in tenon for connecting carpentry parts . It is a cylindrical wooden or plastic rod with a diameter of 6-20 mm, a length of 25-160 mm, the ends of which have a slight sharpening in the form of a chamfer.

Advantages and disadvantages of fastening with wooden dowels

“Nagel” translated from German means “nail”. It has the form of a pin, which is made from a wooden base. This building element comes in two main shapes: square and round.

With the help of a dowel, the possibility of beam displacement is eliminated, due to which all elements of the construction are constantly kept at the same level.

Operating principle of dowels Source drevo78.ru

See also: Catalog of timber house projects presented at the Low-Rise Country exhibition.

The most important thing is that this fastening element has a smooth surface, because otherwise, cracks may appear in the wall. Among the advantages that open up when using dowels in the construction of wooden houses, we note:

• Corrosion is not a problem for them;
• Do not deform when temperature changes;
• During the assembly of structures, dowels do not interfere with the shrinkage of the walls.

This fastening dries out along with the walls, which is very important.

As for the negative aspects of such “nails”, they are absent. In the case where the decision was made to build a house from timber, the choice of this type of fastening will be the most ideal. There is only one caveat - performing work using dowels will take longer and will be more expensive than using conventional metal nails.

Assembling a log house on a dowel

To be or not to be a dowel in a log house? Interesting and hot question! On the one hand, there are hundred-year-old or more log buildings using birch or pine dowels, while in other houses of a similar age there are none. On the other hand, in modern reality, someone claims that installing dowels is mandatory, while others flatly deny its necessity.

Interesting, but true. There are practically no articles about installing dowels in a log house. All information “revolves” around the beam. Why? To do this, it is necessary to remember the characteristics of the compounds that are used with these materials, as well as the specifics of the materials themselves.

Chopped log

Only the bark is removed from the surface, and even that, as a rule, not completely (part of the bast remains when processed with a scraper). As a result, the upper layers of the wood itself are not damaged. If the log is selected and placed in the log house correctly, then the risks of it torsion around its axis are minimal. and increase towards the top of the frame, where its weight is less.

The inter-crown groove and bowl, especially in the Canadian felling, prevent bending and torsion of the log. The only weak points are the joints of logs and saw cuts under door and window openings, where there is only an inter-crown groove and the casing has not yet been installed. It is for this reason that earlier openings were either not cut out in advance, or a casing box was immediately installed, taking into account the shrinkage and shrinkage of the log house. Displacement, provided that the wall is installed vertically, is practically excluded.

Calibrated or rounded log

The log is produced on machines using two fundamentally different technologies. On pass-through machines, the log moves through a rotary head, resulting in a rounded log with the same curvature as the original. On positional type machines, the source log itself rotates, and the output is an even cylinder, the sapwood of which has been removed unevenly.

As a result, in the first case there is already a curvature, which will only increase during shrinkage, and in the second there will be a high tendency to deformation due to different stress forces. In some cases, the torsion of a single log can raise the corner and create a gap of up to 1–2 cm.

The bowl and inter-crown groove also resist torsion and displacement, but their resistance to log deformation is significantly greater.

Planed and unplaned timber

The cheapest option for a solid wood house is an unplaned timber house - this is timber immediately after the sawmill. Since the roundness of the log is sawn off, which, in fact, act as stiffening ribs, its tendency to deformation due to bending and torsion, like any timber in general, is much higher. Planed timber differs only in the additional processing of the front sides.

If a house or bathhouse from such timber is assembled into a bowl, then it partially counteracts torsion, but with a large length of timber, everything is decided only by the total weight, and it is less than in the case of a log.

But in the overwhelming majority of cases, houses made from such material are assembled not into a bowl, but end-to-end, “into a dowel” or into a “root tenon” (warm corner). With these methods, only the upper rows counteract the torsion of the log, and nothing prevents horizontal bending and displacement.

Profiled timber

The situation described above is also typical for profiled timber, with the exception of the situation with bending. This type of deformation is “controlled” in profiled grooves. But if torsion takes the beam out of the grooves, then bending will be possible.

Deformation of timber during torsion

Deformation of profiled timber during torsion

Glued laminated timber

The manufacturing technology of laminated veneer lumber itself is aimed at eliminating the processes of log deformation that are typical for other types of timber. The lamellas are pre-dried in chambers, planed, and then glued together. But this may be the “problem” of laminated timber in a log house, since at a humidity level of less than 12% it will tend to pick up moisture from the air. As a result, laminated veneer lumber can become deformed even before being laid in the log house.

The use of dowels allows you to compensate for the shortcomings of building materials, resisting their deformation.

Dowel connections according to GOST

GOST 300974-2002 “Corner connections of wooden block and log low-rise buildings. Classification, design, dimensions" requires the installation of wooden dowels (dowels) in corner and T-shaped joints of beams with a main tenon and on dowels . These are connections where there is no bowl. The dowel is placed in the center of the corner joint.

Types and forms

Pins are produced with different cross-sections:

1. Rectangular.
2. Square.
3. Round.

Of course, in most cases, round fasteners are used, because it is quite difficult to make a hole for a square cross-section. By type, dowels are divided into: wooden and metal.

Forms of dowels for installing a timber house Source kamtehnopark.ru

Metal is not entirely profitable

If the choice was given to the metal mounting option, then it can be made from reinforcement or will be hollow inside. A beginner will find such material quite difficult to work with, and besides this, there is a possibility of damaging the expensive timber. It is for these reasons that they prefer to work with wooden fasteners. Also, the metal type of dowel is more expensive, which makes it not a very suitable option when building structures made of wood.

Wood is the best choice

Finished wooden dowels for timber must be made of raw material, and they must also be impregnated with a special agent that does not allow the possibility of rotting.

How to make a dowel with your own hands

DIY Nagel

It is advisable to buy a complete set of dowels for building a house; if a few pieces are not enough, you can make dowels yourself. If your household does not have a lathe, you can use a shovel handle. The diameter of the handle is 39-40 mm - this is a lot for a dowel; the excess must be removed with an ax and a plane. A chamfer is removed from the seating edge to form a cone 7-10 mm high, and the surface is cleaned of unevenness using sandpaper. Rectangular dowels for timber are cut from scrap boards using a circular saw or jigsaw, on the seating side the edges of the ribs are cut at an angle of 45-60 degrees, the surface is subjected to finishing (grinding).

Video description

See the video for a clear overview of dowels:
Installing dowels is a fairly straightforward matter. It is hammered into the hole, but not completely, so as not to create a crack in the beam. The pin must fit into the finished hole without undue difficulty, so that the wood can shrink freely in the future. The distance that is left between the fasteners must be calculated based on the construction documentation. Installation is carried out in a checkerboard pattern. Before installing the fastener, it is lubricated with a special construction adhesive, and then hammered in with a mallet.

Drilling a hole for the dowel Source sruboff.org

Fastening technology

Diagram of the dowel connection device

To install the dowel, you will need to perform a number of operations in the following sequence: make markings, drill a mounting hole, install the mount in the prepared hole.

Calculations and markings

The requirements for dowel connections are determined by SNiP 2.01.07-85; when installing dowels, the following rules must be observed:

• The crowns of the log house, corners and junctions of internal walls are subject to fastening;
• Seating places are located along the entire perimeter of the log house at a distance of 1.5-2.0 m;
• Each beam must be fastened to the lower and upper rows with a separate dowel;
• In each crown, the landing hole is shifted by 0.5 m, repeating the configuration is allowed after 2-3 rows;
• Holes are drilled in the center of the beam, with a depth of 15-20 mm greater than the length of the dowels.

Drilling

To drill mounting holes with a diameter of more than 12 mm, use low-speed drills with a power of at least 1200 W with two handles. The drill must meet the following requirements: exceed the length of the mounting pins by 30-35 mm and ensure chip removal. The best solution would be to use wood router bits. It is necessary to decide on the diameter of the drill and dowel at the design stage; you should have 7-8 drills in stock.

A hole is drilled in two crowns at once; to prevent shifting, the upper and lower beams must be securely fixed; for this you can use construction staples.

Installation

The dowels are installed in the mounting holes with tension; for this, significant force must be applied; the deeper the rod goes into the hole, the greater the force must be applied. The danger is that when driven into the timber, the dowel may crack and the upper part may become wet. You can reduce friction with a soap solution; you cannot use paraffin or technical lubricants for these purposes.

You should have a wooden or rubber mallet, a heavy and a light hammer on hand. The blows are applied strictly vertically; when using a metal tool, it is necessary to use a protective pad made from a piece of thin board or multi-layer plywood. If a crack develops in the rod during installation, it must be drilled out and the operation repeated.

Bottom line

Assembling timber on dowels made of hard wood is the most profitable and optimal choice when you need to reliably connect the structure of a building. Such a fastening element can provide strength and longevity to the construction, as well as eliminate the possibility of wood deformations. The use of such a fastening element is irreplaceable, because it makes it possible to prevent the possibility of displacement of the crowns of the log house, which can occur due to shrinkage during operation. In this case, the wood dries evenly, thereby maintaining the integrity of the walls of the houses.

Features of nails and pins

Everyone knows what a nail looks like. This is a rod made of relatively soft carbon steel. There is a cap on one side, and a point on the other. The nails are driven into the wood with a hammer and quite securely fasten the two parts together.

Many imagine Nagel worse. This is a relatively long wooden cylinder. To fasten two beams with it, a hole of the same diameter as the dowel is drilled with a drill. The hole goes right through the first beam, and almost right through the second. Since the diameters are the same, the dowel should fit into the channel with virtually no effort. Then the dowel is hammered in flush with the surface of the timber. After this, it is also slightly sunk with a special tool (a hammer). As a result, the dowel sits at a depth of 30-50 mm from the surface of the beam. If the wood shrinks when it dries, the dowel will not protrude above its surface.

Compared to a nail, a dowel has a number of features:

1. The wood does not pull together.
2. There is also no fastening of the logs in the vertical plane. The dowel does not prevent the timber from moving up or down.
3. If the wood begins to deform during drying, the dowel will not interfere with the subsidence of the beams, but will not allow them to turn sideways.

In order for the dowel to fully perform its functions, it is important that the holes for it are drilled strictly vertically, and their diameter exactly matches the diameter of the embedded element.

Classification of dowels for concrete

The concrete screw or dowel is available in several versions. Each type of fastener differs in the metal used for manufacturing, the shape of the head, the design of the threaded part, the type of coating and the price.

Metal fabrication

A dowel or screw for concrete is created from the following materials:

• stainless steel - steel with alloying elements;
• brass is an alloy containing zinc and copper;
• Carbon steel is a metal made by combining iron with carbon.

A self-tapping screw for concrete made of carbon metal is the most common type of dowel. This type of steel allows you to create fasteners that do not deform even when screwed into a solid concrete base.

Head shape

Steel dowels are available with countersunk and protruding heads. Hardware caps can have the following design:

• conical shape with a slot for a cross-shaped tool;
• hook or loop;
• a threaded rod for a nut to secure the part being fastened;
• hexagon of regular shape or elongated with internal thread (both options are tightened with open-end wrenches);
• in the shape of a conical head with a slot in the form of a six-pointed star.

The type of cap affects the method of mounting the dowel. Most types of specialty screws can be installed without first preparing the hole. The exception is self-tapping screws with a hook or pin. For them, you need to prepare a hole in advance and install a plastic dowel.

Thread design

Steel self-tapping screws for brick and concrete, depending on the design of the threaded part, are available in the following designs:

1. Multifunctional fasteners with medium thread, diameter up to 6 mm and maximum length 20 cm. These are universal self-tapping screws for concrete without dowels. To use them, it is not always necessary to pre-prepare the hole. If necessary, they can be used together with dowels.
2. Fasteners with herringbone threads, with a maximum diameter of 8 mm and a length of no more than 20 mm. Dowels are used only in conjunction with dowels. Therefore, it is first necessary to prepare a hole in a solid base. If there are voids in the concrete, an impact dowel with a length no less than a dowel is used.
3. Variable types of fasteners with notches are hardware from 7 to 20 cm long with an intermittent thread with a diameter of 7.5 mm. Before using the dowel, you must first prepare a hole with a smaller cross-section than the same size for the fastener. In this case, the depth of the channel in a solid base must be 1–1.5 cm greater.

In Russia, a variable type of hardware with notches is more often used. Builders also call it a turbo screw. Typically, fasteners with a countersunk head are used, which is tightened with a Torx socket. The smallest pull-out load of this dowel is 2.5 kN. It is used in concrete walls of varying densities. It is recommended to create a maximum torque of 20-25 Nm during installation.

Coverage type

The color of the dowel allows you to determine the type of coating:

1. Yellow concrete screws are coated with zinc of the same color. They are used exclusively indoors.
2. Self-tapping screws for concrete of a silver shade, which are galvanized. Fasteners are used inside and outside objects.
3. Blackened dowels are used only in rooms with normal humidity.

The cost of special screws for concrete surfaces is mainly affected by the length of the fastener and the type of protective layer. The highest price is for galvanized hardware, and the cheapest are blackened screws.

Manufacturing nuances

In addition to the shape, concrete screws have other differences. Depending on the type of protective anti-corrosion coating, the following are applied:

• galvanized. This type is suitable for most construction operations: interior work, facade work, basements, roofs, etc.;
• copper-plated or blackened. Both types have reduced resistance to moisture and are unsuitable for use on facades and basements. Used for interior work in dry rooms.

An example of how the sizes of a dowel for a 6 mm drill can vary:

• outer section – 7.35-7.65 mm;
• diameter with thread – 6.3-6.7;
• thread pitch – 2.55-2.75;
• internal section without thread – 5.15-5.45;
• head height – 2.8-3.2;
• cap diameter – 10.82-11.82;
• slot depth Torx 30 – 2.3-2.7;
• rod length – 50-184.

Shapes of dowels

Installation features

The depth of the holes must be 2 cm greater than the length of the dowel itself. This requirement is due to the fact that when shrinking the log should not hang on the fasteners. The connection with dowels is accompanied by a tight fit of the rod into the socket. However, you don't have to make any special efforts. But the mallet must still be used. It is important to note that the fasteners should not be loose in the hole.

Metal pin

Metal fasteners are rods, which are used much less frequently. This fact remains true despite the durability and higher strength of such products. Among the main disadvantages, one should highlight the high fastening strength, which eliminates wood shear.

But metal dowels have many advantages, namely:

• consistency of size;
• ability to resist warping of the top layer of material;
• easy installation.

As for the first factor, the same cannot be said about wooden dowels, which will come out of the holes when dry. If ease of installation is an important point for you, then you will choose metal fasteners, since during its installation it is possible to use spring ties, which simplifies construction. But metal has high thermal conductivity, which certainly causes the formation of cold bridges.

Such fasteners hold wood extremely rigidly, while the difference in thermal conductivity causes condensation to appear in the places where the fasteners were made. Typically, metal pins have corrugated surfaces, which leads to damage to the material. In order to achieve positive results, quite often builders combine the fasteners described above.

Conclusion

From the article you learned that concrete is considered one of the most practical materials for placing various elements on its surface. To do this, metal products are used in the form of self-tapping screws, anchors and, of course, dowels, which differ from others in the ability to screw a ceiling or floor into a wall without prior preparation of a mounting hole.

The latter has different head shapes and is used for external and internal work. The video in this article will help you find additional information on this topic.