Bar according to gost and its application

All coniferous lumber sold without violating the rules of trade are governed by the State Standards of the Russian Federation. Similarly, timber according to GOST 8486-86 and others must have certain quality parameters, which include cracks, knots, wormholes, spots and so on, as well as geometric parameters of the profile.

We are not going to lay out absolutely all the requirements that this standard provides for, but pay attention to the main ones and what it gives in practice, and also watch the video in this article on this topic.

What give state standards in practice

Practice is a great thing and all norms and rules that do not agree with it are just an empty sound or a dummy on paper. So, the assortment of wooden lumber according to GOST allows for its purchase in accordance with the assembled structure, that is, to choose lumber not only in size, but also in grade, which corresponds to one or another state of products.

Standard

First of all, it should be noted that the bar, unlike the board, is divided into 4 grades, therefore the dimensions of the wooden bar according to GOST 8486-86 or another, as well as its quality will be shown in this correspondence. Below you can see the tables that display all the requirements inherent in this standard.

Reference: The number of knots in the bars on State Standards is not subject to normalization.

Explanations:

1. If the knot size is less than half the maximum allowable value, then such a marriage is not taken into account.
2. If the lumber thickness is from 40 mm and more, then the instruction allows elongated and cross-linked knots on the minor axis up to 6 mm with a depth of 3 mm. There are no size limits along the major axis. For selected varieties, these tolerances are not valid.
3. According to the norms of ununited knots, the stepson is allowed. For selected varieties, these tolerances are not valid.
4. The knot size is determined by the distance between the tangents to the contour, held parallel to the longitudinal axis. For the size of the elongated and cross-linked knot on the faces of the lumber and on all sides of the bars and bars take half the distance between the tangents, held parallel to the longitudinal axis of the lumber.
5. If the length of lumber exceeds 3m, then a knot is allowed in this area with dimensions provided for by the lower grade.
6. On a section of the length of the lumber equal to its width, the number of knots should not exceed the amount prescribed by the norm.
7. If sawn timber is used for load-bearing structures, then in such cases on a plot of 200 mm in length the number of knots should not exceed the quantity specified by the norm.

Explanations:

• These sizes of cracks are permissible for sawn timber, the moisture content of which does not exceed 22%;
• In that case, if the humidity is greater, then the size of the cracks should be two times smaller.

Explanations:

1. The sawn timber that is exported must be completely bark-free.
2. If the cut of sawn timber exceeds the allowable rate, then this material is considered as uncut.

Reference: This table will help you to regulate the type of material regarding its use for a particular design.

Explanations. According to this table, you can determine all the coniferous bars according to GOST, comparing it with one or another item in which requirements are recorded.

The benefits of state standards

• Having gone through the shops of building materials or wholesale bases, you will certainly notice the difference in the cost of seemingly exactly the same bars that you need to purchase for any design. As a rule, sellers explain such a difference by the fact that the purchase price does not stand still or with a range of transport, although this is not the main factor, and how can sellers know this! You can hear clearer explanations on the sawmill, and even from simple workers who are not related to the purchase and cutting of materials, but which are directly related to its sorting.
• In the same way, the master who will collect this or that construction will pay attention to what is paid attention to when sorting and the sellers hardly notice. These are exactly the permissible errors that are indicated above in the photo of the tables with the requirements of GOST. Of course, no one will recalculate knots on the length of the beam or measure their depth, they will not carry out the same procedures with stains, cracks or a glaze, but all this determines the appearance of the product and often what the seller does not see or does not want to see will see an experienced master.
• For the carpenter, the color of the stain on the tree, its moisture, and most importantly the clarity of the profile lines, will tell a lot. The author of this article, having a solid experience in the production of repair work, has never in his life been faced with the fact that the seller has paid attention to the clarity of geometric parameters. They see everything - cracks, rot, mold, stains, chips, but the “helicopter” on the rail or the difference in cross section from both sides - never!
• It is for this purpose that the standards listed above exist, and if in private construction most often they buy a plank or cant "by eye", then for industrial and civil objects the contractor requires accompanying documents from the supplier, in which compliance with this or that standard is indicated. This is quite understandable, because large-scale construction requires large-scale purchases, and visual inspection is simply unacceptable here — not enough time. The supplier must be responsible for the quality of the goods and if the contractor makes a marriage due to poor-quality material, then the responsibility in this case lies with the person who signed the act of acceptance and compliance with state standards.

• Compliance with standards makes it possible to build load-bearing structures from a beam, for example, such as you see in the upper photo - boards, slats and bars are used in conjunction with a metal profile. All together forms the bearing structure or wooden frame of the expanded balcony, on which the siding will be fixed, and he will later have to withstand the gusts of wind of any force. For such structures, as a rule, the first or second grade of sawn timber is used, since the subsequent loads are quite large and a margin of safety is necessary.

• Also, lumber can be made and more voluminous structures, such as farm building, bath and even at home, although for this purpose now often used profiled timber. However, a smooth profile is always needed, for example, to assemble a roofing frame from a timber. Where, again, you need high quality.

Conclusion

Of course, the dimensions of the timber according to GOST, its structural qualities and humidity are very important for the construction of facilities where the lumber will not perform a temporary mission (supports, formwork, fencing), but will remain as part of the design. Therefore, the state of wood, which the master determines visually at small volumes, is regulated by state standards for large construction.