Reasons for the appearance of cracks in the timber and ways to prevent their formation

1.Cracks in the timber are formed due to uneven shrinkage

Cracks in the timber occur due to the fact that the humidity inside the timber is higher than outside. Thus, the outer part of the bar "breaks", because it bursts from the inside.

In the language of specialists and in the textbook, such defects in wood building materials are classified as follows: "Cracks are longitudinal ruptures of wood formed under the action of internal stresses reaching the tensile strength of wood across the grain ..."... Cracks in lumber are different, but in this article we are discussing cracks shrinkage, the reasons for their occurrence and ways to overcome their occurrence in the bar.

The moisture content of the timber and its drying affect the quality of the wood of the building material. Drying is atmospheric and chamber: in the first case, the timber dries out naturally, and in the second case it is forced. The formation of cracks in the timber depends on how the chamber drying is carried out, whether its technologies are followed.

Drying of wood is accompanied by an uneven distribution of moisture in the body of the bar, which causes an uneven level of moisture in the wooden building material and leads to the formation of internal stress in it.

With atmospheric drying, the timber naturally reaches the required moisture content, being in a frame shrinking for up to six months. Thus, the drying process is delayed in time, but the internal stress in the wood often balances (or approaches its indicators) with the external one, because in a natural environment, air humidity is higher than in drying chamber, which smoothes the effect of bursting wood from the inside. Simply put, drying out from the inside, the timber is saturated with atmospheric moisture from the outside, which leads to a slowdown in the drying process, but, at the same time, to a more gentle drying, gradual balancing of moisture outside and inside in accordance with the environment.

In order to speed up construction, developers sometimes resort to buying a chamber-dried log house to get a house immediately without shrinkage, on a turnkey basis. Such construction is not only much more expensive, because dry lumber is higher in price due to the cost of electricity for its production, but also leads to a poor-quality structure - some manufacturers of dry timber violate the drying technology at high-speed drying mode.

It is not enough to simply place the raw material in the drying chamber and turn on high fever... Special temperature conditions must be observed during the entire production of dry lumber, and at the end also connect steam in order to prevent cracking of the wood from the outside, soften it so that internal stress does not tear the outer layers.

2.Compensation groove in the timber helps prevent cracking

One way to overcome the internal stress in the bar and, therefore, to minimize the formation of shrinkage cracks in the bar is the so-called. "Compensation grooves" in the timber, which are sawn simultaneously with the manufacture of the most wooden building material.

The relief cut relieves part of the internal stress in the bar, because functions as if artificial cracks - they are made in advance, before the appearance of real ones, but since they hide under the lower and upper crowns during the assembly of the frame, they become invisible and do not spoil general form buildings.

When a timber that has dried out from the outside bursts with tension in the still wet middle part from the inside, it either breaks at the sides, forming cracks, or slightly opens up in the expansion grooves. When the moisture leaves from the inside, then it closes in dreams and the bar takes on its original, albeit already shrunken form.

Visually, it is difficult to notice changes in the relief cut and this does not affect the mechanical properties of the wood and the quality of the log house.

The expansion groove is made both in the timber of natural moisture and in a dry one. It helps to overcome the internal stress in the wood, regardless of how the moisture will leave it - naturally during shrinkage or forced in the drying chamber.

The presence of an unloading cut in the timber does not guarantee the complete absence of cracks, but significantly reduces their formation: the softer and more natural the process of moisture release from the wood structure, the less deformations in it.

3.Other reasons for the formation of cracks in the timber

Another reason for the formation of cracks in the timber is sawing the timber through the core of the log. In the case of using sawing without a core, the timber does not shrink during shrinkage, and the formation of cracks is minimized.

It is possible to establish from which part of the log the timber was made by the annual rings at the ends of the lumber: they are wider at the core, and taper towards the edges. But this is often only possible for specialists and a common man in the street does not pay attention to these details. Therefore, when choosing a building material, consider the timber not only from the sides, but also from the end ones.

Thus, in order to build a beautiful and high-quality house from a bar, pay attention to the quality of the lumber, from which your suburban structure will be built. It is important how the house will be built: from a bar of natural moisture for shrinkage or from a dry bar, which is used for construction immediately for finishing. Atmospheric drying of timber assumes the formation of a minimum number of cracks, in contrast to forced drying timber, the manufacturing technology of which can be violated, especially during the hot construction season.

Ask your timber lumber suppliers about the presence of a compensation groove in the timber. The relief cut, although it does not completely save from the formation of cracks, significantly reduces their number.

When examining the supplied wooden building material, pay attention not only to the side parts, but also to the ends of the timber, which can tell a lot about the quality of the log used in the manufacture of the timber.

During operation wooden houses or baths, cracks begin to appear in the timber. This process cannot be prevented, as it is typical for wooden buildings.

Why it is advisable to close cracks in the timber

Small cracks on the wood surface do not negative impact for the operation of the building. Most often, they can have a character decorative element, giving the logs a certain personality. Still, cracks should not be neglected.

If cracks in the timber have a width of more than 5 mm and spread over the entire log or timber, then it is necessary to take measures to prevent their spread. Why do this?

• Water will get inside the cracks, the moisture content of the wood will increase and it will start to rot.
• Wood cracks are a favorite place for various bark beetles, which, feeding on wood, will render even the most durable logs unusable.

Therefore, if deep cracks are found, they must be repaired immediately.

Prevention of cracks

To prevent cracks in the timber, a number of measures must be taken.

Sealing cracks in timber:

Preventive measures help prevent the appearance a large number cracks, but they are not able to completely eliminate their formation. You can hide cracks in the timber, to prevent decay processes in them by sealing.

Sealing cracks in timber possible different ways... The most commonly used materials for this are air-hardening putties, dry mixes, and sealants.

Methods for sealing cracks in a bar

The above methods of sealing cracks can be used both outside and inside a house from a bar. All methods do not harm the wood, help remove cold bridges and increase the strength of the wood.

Hello!
I am a pro in this area, dozens of times I have witnessed the selection of planed timber by capricious townspeople, and sometimes these criteria "SHOCK" to say the least.
Here is the answer to your question in the article: - "Planed dry timber - selection criteria!" I strongly advise you to read it before making a purchase. buying this bar is not a very cheap pleasure and you need to clearly know and understand what you pay big money for. In order for the answer to be complete and to remove all questions on this topic, I will begin to describe the field of application in the construction of a planed bar.
APPLICATION AREA:
Section 200x200.
Designed for the construction of a "well" frame load-bearing walls wooden house, and practically does not shrink because it has passed chamber drying (has a moisture content of up to 20%). It has no deformation along its entire length, it has a perfectly smooth and even surface on all four sides. This is not insignificant, since many have not spent small amounts of money on the purchase of this bar, not even spending money on interior decoration, simply chamfer inside edges of the timber and use it as an element of decor inside the living quarters of a wooden house. However, it is also used as a decoration in the manufacture load-bearing elements wooden house.
This section of dry planed timber is not standard and is not mass-produced, it has the character of piece production. On trading platform available from 6 to 10 pieces. no more. Before buying, you need to clarify the number of pieces available.
Section 200x100.
This beam is intended for the construction of the rafter and floors between floors. Wealthy townspeople sometimes require that the floor logs also be made from a bar of a given section, since it has been heat treated and dry. As practice shows, they leave it open as an element of decor after processing with septic tanks in the required color. Passed chamber drying (has a moisture content of up to 20%). It has no deformation along the entire length because it was sharp on the machine and has a perfectly smooth and even surface on all four sides. Chips, potholes and scratches are not allowed, therefore each piece is packed in transparent celoffane bags. This is not insignificant, since many, having spent a lot of money on the purchase of this bar, not even spend money on finishing, are used in the manufacture of load-bearing elements of a wooden house.
Section 150x150.
This beam is intended for the construction of a "well" of the frame of the load-bearing walls of a wooden house, and practically does not shrink because it has passed chamber drying (has a moisture content of 15 to 18%). Given this circumstance, you can proceed to the interior decoration of the premises of a wooden structure. It has no deformation along the entire length because it was sharp on the machine and has a perfectly smooth and even surface on all four sides. This is not insignificant, since many having spent a lot of money on the purchase of this bar do not even spend money on interior decoration, they simply remove the chamfer from the inside of the edges of the bar and use it as an element of decor inside the living quarters of a wooden house. However, it is also used as a decor in the manufacture of load-bearing elements of a wooden house, for example, stairs.
Section 150x100.
This bar, like 200x100 (see section 200x100), is intended for the construction of the rafter and floors between floors. Chips, potholes and scratches are not allowed therefore each piece. pack in transparent whole. packages.
Section 100x100 and 100x50.
Used in frame construction.
As long-term practice shows, planed-dry timber, due to its high cost, is used mainly as a decor, subjecting it to minor processing.

Houses made of profiled timber are considered the most convenient and comfortable to live in, moreover, very attractive. After making this material already has a wonderful appearance, so, by and large, it does not need finishing. Many owners log houses they don’t do it. But over time, the owners begin to notice that cracks form on the even and smooth walls.

Why does profiled timber crack? and how dangerous is it? Let's try to answer these questions.

Reasons for cracking timber

There is such a science - "wood science". According to her, wood in the process of drying can decrease in size, that is, dry out. In particular, the drying out of pine will be, as a percentage:

• across the fibers - 3-5%;
• along the fibers - 0.1-0.3%.

The shrinkage of the outer and inner layers also differs. For example, in the same pine, the dimensions of the inner layers decrease by 2.91%, and the outer ones by 8.22%. But this is only if the wood dries naturally. If the production of profiled timber is carried out from a pre-dried material, it cracks much less, and the size of the cracks is not very large.

In addition, during shrinkage, tensile stresses act on the surface layers, and compressive stresses on the inner ones. It often happens that their value becomes greater than the tensile strength of the tree, as a result of which the upper layers crack. The same situation is observed not only with profiled timber, but also with rounded logs. Consequently, with natural drying, the outer layers dry first, after which the inner ones. This means that in any case, the timber and logs will crack. The only thing that can be done in this case is to reduce the size of the cracks.

Wood protection methods

Now you know, why does the profiled timber crack?... There are several ways to deal with this. Here are the most common ones:

1. Dry for a long time. It will take at least two years for the logs to dry completely. Only then they will not crack so much, and the size of the cracks will be within 1-2 mm.
2. Make a compensation cut. The effectiveness of this method is in question, there are still disputes about its feasibility and safety.
3. Drying with high-frequency currents - in this case, the process occurs as if from the inside - first the insides dry, and then the surface. However, the cost of a tree dried in this way is simply transcendental. In addition, some experts are not sure about the harmlessness of exposure to high-frequency currents.
4. Chamber drying is the most preferred method. Thus, most manufacturers dry the material.

How dangerous is cracking

While lumber manufacturers and sellers of specialty crack bridging products do their best to reassure buyers of the dangers of cracking, the reality is not so bad. Here are the arguments they make:

1. If the timber cracks, then when moisture gets in, it freezes in winter and can break it.
2. As a result of cracking, rotting begins.
3. Insect pests accumulate in the cracks.
4. Thermal insulation properties houses are down.

To be convinced of the controversy of these statements, it is enough to go to the nearest village and look at the houses there - the walls are simply teeming with cracks. Nevertheless, the people living there do not notice any danger.