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With independent construction, you have to buy lumber – timber and board. The board is usually bought in cubic meters, and the timber is considered by the piece. They sell at small volumes with the calculation, by the piece, and at large volumes it is more convenient in cubic meters. In order not to miscalculate, you need to know how much timber is in a cube. Sometimes manufacturers indicate the quantity in the description, but it is better to be able to calculate it yourself.
Why do you need to know how much timber is in a cube
To begin with, let’s figure out what is considered a bar. Lumber, in cross section having the shape of a rectangle, the width and length of which is at least 100 mm, is called a bar. Anything less is called a bar. That is, 100*100 and 100*125 is a bar, 100*75, 100*50 is a bar. These are terminology features, but it is worth knowing this so as not to get confused in the assortment.
Why do you need to know how many pieces of timber are in one cube? For example, for construction, 45 pieces with a size of 150 * 150 and 23 pieces with a size of 100 * 100 are required. How many cubes will you order? You need to look for a table for converting cubes into pieces (they also call the cubature of a bar), or count it yourself.
Calculation from tabular data
The option with the table is simpler – count less, however, keep in mind that the table shows a standard length of 6 meters. If you need such material – no problem. In this case, see how much timber of this size goes into 1 m³, divide the amount you need by this number and get the number of cubes. The number is usually a fraction, so round up to the nearest whole number. When the fractional part is small, you can try ordering 2,5 m³ or 3,5 m³. Some vendors do this.
To make it clearer, consider the calculation with an example. As already mentioned, 45 pieces will be needed. timber 150 * 150 and 23 pcs. “hundreds”. According to the table, we see that 100 * 100 in one cubic meter are 16 pieces. We need 23. So, 23/16 = 1,4375 cubic meters and it might be better to order 1,5 cubic meters. After all, it is better to have a stock than to buy more material later with new shipping costs. If there are leftovers, they will be useful for some other purpose.
When talking about lumber, more often the dimensions are indicated in millimeters: 200×200, 100×150, etc. But sometimes the size is given in centimeters: 20×20; 15×20, etc.
Let’s calculate how many cubes of timber 150 * 150 mm we need. In one cube of a bar of this size, according to the table, there are 7 pieces. We consider: 45/7 = 6,428 m³. We round up and it turns out that we will need 7 cubes of lumber of this size.
How to calculate yourself
If there are tabular data, the calculation is quite simple. But the table does not always help. This only works if you require standard length material. Often you have to cut a beam – in order to grow to the desired length or into small piers. Buying a standard for sawing is expensive. Timber of smaller lengths costs much less. It is considered a re-grading and is cheaper. How to calculate correctly in this case? It’s not that hard, elementary school math.
To calculate, you need to know the volume of each unit. The material is a strongly elongated parallelepiped, which means that we need a volume formula. It is necessary to multiply all the dimensions – length, width and thickness.
For example, let’s calculate the volume of a bar 150*200*4000. All data are given in millimeters. But we need cubic meters, and for this we will convert millimeters to meters, that is, we will divide the result by 1000. So, we get: 0,15 * 0,2 * 4. These are the same dimensions, only in meters. Now we multiply everything: 0,15 0,2 4 = 0,12 m³. It turned out that one beam of a given size has a volume of 0,12 cubic meters. It is easy to calculate how much a bar of this size will be in one cube: 1 divided by the resulting volume. 1/0,12 = 8,33 pcs. That is, you will be shipped 8 pieces.
You can also calculate how many pieces in a cube of planks or boards, and any rectangular lumber. Just remember that all dimensions must be in meters. Then get the correct result. For verification, we give a table of the number of boards (grooved and edged) of different sizes in one cube.
Calculation of material for construction
If the beam goes to the supports, truss system, counting the number of pieces is easier. But how to calculate how much it is needed for a house, without counting the number of crowns? You can, of course, and so, but it’s easy to make a mistake. How to find out how much material is needed for the house? Determine immediately with the cubature.
Example. House 12 * 10, height to the top crown 2,8 meters. We will build with a bar 200x200x6000. We don’t need to know the number. Let’s calculate how many cubes will go to the outer walls.
The calculation procedure is as follows:
- We consider the perimeter of the house. In plan, the house looks like a rectangle, so (12 + 10) * 2 = 44 meters.
- Now we multiply the perimeter by the width of the wall (in this example, it is 200 mm or 0,2 meters) and by the height of the walls – 2,8 meters. We get: 44 * 0,2 * 2,8 = 24,64 m³.
- We round up, we got that for the construction of external walls we need 25 cubes of timber with a width of 200 mm.
- If it is necessary to determine how many pieces exactly will turn out, it is necessary to divide the total volume of 24,64 m³ by the volume of 1 piece. From here we get 24,64 m³ / 0,24 m³ = 102,66.
The height of the house can be any, here you decide for yourself. There is a difference in the price of the material, because a larger timber is more expensive. You need to recalculate if you decide to change the width of the wall and make, say, 250 mm. In this case, instead of 0,2, we substitute 0.25. 44*0.25*2.8 = 30.8 m³. That is, it will take 6 cubes of timber more. This is logical, since by the number of timber 250×250 will be less in a cube, and by volume more than 200×200.
How much does a cube of timber weigh
Why know the weight3 timber? In order not to miss the delivery. If you pay for the delivery and order, you will need to take into account the weight in addition to the cubic capacity. And, of course, the weight of the structure is required when calculating the foundation.
The weight of any lumber depends not only on the size, but also on the humidity and the type of wood. You can’t define it on your own. So it is necessary to be guided only by tables.
| Tree species | Weight 1 cubic meter wood in kg at different humidity | |||
|---|---|---|---|---|
| Dry, 10-18% | Air dry, 19-23% | Raw, 24-45% | Fresh cut and wet, >45% | |
| Linden, cedar, poplar, spruce, fir | 450 | 500 | 550 | 800 |
| Alder, pine, aspen, willow | 500 | 550 | 600 | 800 |
| Birch, elm, chestnut, larch, elm | 600 | 650 | 700 | 900 |
| Acacia, beech, hornbeam, oak, ash | 700 | 750 | 800 | 1000 |
The volumetric weight table shows the weight (in kilograms) of one cubic meter of lumber for different types of wood, at different humidity. To find out how much your order will weigh, choose the breed and moisture content of the ordered material. Find the number at the intersection. Multiply it by the number of cubes.
Example. We will order 25 cubes of air-dried pine lumber. One cube of pine in this condition weighs 550 kg. Weight of 25 cubic meters: 550 * 25 = 13 kg. Approximate weight will be 750 tons. Such a task can be handled, for example, by an onboard KAMAZ 14 with an awning or a Volvo F65117, etc.