Standard sizes of edged boards, how to determine the grade

When purchasing materials, it is best to be aware of what size they should be, how to identify the grade, and what the differences are between different species. We will discuss all this, and we will also give the standard sizes of edged boards and permissible deviations.

What is edged board, beam and bar

It is not so easy for an ignorant person to understand construction terminology. If you started a construction project, you will have to do this. To begin with, let’s figure out what a board is, how it differs from a bar and a bar. All definitions of lumber are given in GOST 18288-87. They rely on size. According to this document:

• A board is sawn timber having a thickness of not more than 100 mm and a width of more than twice the thickness.
• Beam – with a width and thickness of more than 100 mm. The maximum size of the beam is not standardized. Only minimal.
• A bar – up to 100 mm thick and not more than twice the thickness wide.

So, if you look at the bar from the end, all its sides should be equal. The cross section of the beam will give us a square. The board and the bar are rectangles. It’s just that the width of the board is more than twice the thickness, and the bar is less. For example, 25*75 mm is a board, and 25*45 mm is a bar. And, by the way, 50 * 50 mm and 75 * 75 mm are also a bar, not a bar, because according to the standard, a product with a side of 100 mm is considered a bar. With these names, like, sorted out.

For rough work, a slab is sometimes used. What it is? According to the same standard, this is the side of the log, one side of which is propylene, the other is not. There is also a plank slab – this is when the outer part of the slab is partially propylene.

Edged and unedged board

It is also worth deciding what a face and an edge are. This is either of the two wider surfaces in the board or bar, and either of the surfaces in the bar. The edge, respectively, is the narrower part of the lumber.

Now you can find out what a cut board is and how it differs from an unedged board. The edged board has edges sawn perpendicular to the layers. There may be a wane (remnants of the bark) on the edge, but no more than is acceptable in terms of grade. An unedged board, respectively, has uncut or partially cut edges. The same category includes edged lumber in which the wane exceeds the allowable limits.

There is also a semi-edged board. This is when only one edge is even, and there may be a wane on the second. A bar, by the way, can also be with a wane. A two-edged one has two opposite sides, a three-edged one has three, and a four-edged one has all four.

You may also need such a thing as calibrated lumber. There is a calibrated board, a bar and a bar. This is lumber dried and processed (on a thicknesser or planer) to the required size. It should be understood that an uncalibrated one may have deviations in size (the limits of deviations are normalized), a calibrated one should not differ in size. Rather, the tolerances are very small.

There is also a planed board. It differs from the edged one with smoother sides, as it undergoes additional processing. The edged board is dried, and then sent for additional processing on a planer. There, its roughness, which was left by the saw, is removed. Calibration may occur at the same time, but this is not required. Planed board may not be calibrated.

Business and construction board: what’s the difference

Also in the price lists there is a board with the same dimensions, of the same grade, but one is construction, and the other is business. The difference is that the business one is made from non-dry trunks. It is dried, has no fungal or bacteriological lesions, wormholes, even if they are allowed by the standards. Therefore, it costs significantly more.

The business board is applied at the device of a roof. Goes to the logs, rafters. It is also used in frame housing construction. A business board can be processed directly at the enterprise with the necessary compositions, but this is discussed specifically before delivery.

Sometimes you can see two items in the price list with the same name, but one has GOST, the other either has no mark, or it says “without GOST”. The price difference is significant. How is the material different? First, the size may be smaller. Everything that does not pass the tolerances goes into this category. For example, the width or length, the slope of the bevels do not fit into the standards. Is it possible to take such a board or beam? Depends on where you intend to use it. But such material must be inspected for yourself. The whole party. The lower price is not always the best.

Wood requirements and grade

The grade of a board or its grade is a classification that indicates the permissible flaws in wood and their number. The board and bars can be of five grades – selected, 1st, 2nd, 3rd and 4th. The timber is not selected, so it has only four grades, indicated by numbers.

Lumber of selected, first, second and third grades is made:

Wood for the fourth grade is not regulated. Grading is determined by the worst face or edge. That is, find the worst part, and determine the grade by the presence and number of defects and flaws. All of them are given in the tables, and the possible defects themselves are in the form of pictures.

Please note that the grade data is taken from GOST 2140. It is used for sawn timber for the domestic market and for export. Recently, another standard has been adopted: GOST 26002 for sawn timber, which is sold only in the domestic market. There, the varieties are defined differently (and the tolerances in size, too). So be careful, specify according to which GOST the grade was determined.

How to determine the grade of the board

Do you know how the grade of a board is determined in production? Approximately. Nobody counts knots, cracks and other defects. And the difference between, say, the first and second grade is very small. And not all manufacturers really try to sort it correctly. So it’s better to control everything yourself. But the tables are so big, and there are a lot of defects – it’s unrealistic to remember everything. But there are certain criteria that can help you determine how good the quality is.

• If there is at least one fallen knot, it is definitely not the best and not the first grade in front of you. At least the second, and even lower.
• On boards and beams of the first grade there should be no rot, fungi and core. These are all places that are destroyed in the first place. So they shouldn’t be.
• When choosing a timber, pay attention to the number of annual rings. The more of them, the higher the quality of the wood.

It is also worth looking at the storage conditions. In general, a board of high grades should be stored at least under a canopy. It should be stacked in ventilated stacks, not in bulk. Ventilated stacks are those with spacers that separate one row from another and allow the wood to dry evenly.

Standard edged board sizes

According to GOST 24454-80, there are softwood sawn timber of standard dimensions. The thickness and width of the board is given in the table. According to the thickness of the edged board, bar and bar, deviations are permissible, but they cannot be more than:

• ±1 mm for boards and bars up to 32 mm thick;
• ±2 mm for lumber from 40 mm to 100 mm;
• ±3 mm for thicknesses of 110 mm or more.

There are also restrictions on width deviations: the run-up can be up to 2 mm with a width of up to 100 mm, and up to 3 mm with a width of 125 mm or more.

The standard dimensions of the edged board are indicated for wood with a moisture content of 20%. For materials of higher and lower moisture content change. The shrinkage value is prescribed in GOST 6782.1.

In addition, the length of lumber is standardized. It can be from 1 meter to 6,5 meters. The gradation step is 25 cm. Permissible deviations along the length are 25 mm or +50 mm.

Please note that GOST 26002 has been introduced, in which other deviations are allowed for the domestic market. But there is a postscript: in agreement with the consumer. That is, when buying a board of “standard sizes”, see GOST. In 24454-80, the requirements are more stringent. In it, by the way, other criteria of sorting are established. So, really, it is worth asking what GOST the products are labeled according to.