Before carrying out any construction or repair, always calculate the required amount of material. For example: brick, rolled metal or lumber: unedged, edged boards or lining. Usually the seller provides timber delivery services, but sometimes this is not possible. And already this question has to be decided by the buyer himself: what kind of machine should be ordered in order to bring the required amount of forest to the construction site?
Features of lumber
Even if the amount of wood in cubic meters is known, then the choice of the machine will still need to be calculated according to the carrying capacity. Even knowing how much a dry board cube weighs, the weight of a cubic meter of material on the market can vary significantly. And the reason for this will be not only the wood species, for example: pine or spruce, birch or cedar, but also the place of the log house, the humidity of the surrounding air, and even the time that has passed since the day of the log house. The weight per cubic meter of the same tree will also differ from the degree of processing of the material. The mass of round timber, under the same conditions, will always be less than the mass of unedged timber. This is due to the fact that the packing density of the material in one cube will be different. Round timber cannot be stacked tightly on top of each other; large voids will remain. The same applies to unedged boards. The surface will not press tightly on the sides.
Therefore, when calculating the carrying capacity of a transport, you need to focus on the transportation of the maximum possible mass of cargo. So you need to find out how much a cube of edged boards from pine of natural moisture weighs? Since this is the state of the tree during its felling, and therefore the maximum moisture and density.
Indicators affecting the weight of lumber
Wood moisture is a very important indicator that you need to pay attention to. With her high degree the tree swells, and at low, on the contrary, dries out. All construction work is recommended to be performed with already dried lumber, in which the indicator of moisture does not exceed 15-20%. Otherwise, the established damp forest, over time, dries up, will change its geometric dimensions (decrease) and thereby violate the integrity of the building.
Dried wood becomes more durable, lends itself well to finishing, is not susceptible to mold and insects, retains its construction qualities... The remaining bark is removed before drying. This is necessary for uniform drying and exclusion of damage by insects (bark beetles).
Forest drying is carried out by specialists at outdoors... The timber is laid in a pile, on gaskets between the rows, so that the air passes freely and dries the boards from all sides. It is advisable to locate the drying area in a place where direct sunlight does not fall on the material, but there is good ventilation. The top row of the stack must be pressed with a load to prevent deformation.
Weight calculation
Now let's calculate the weight of the most common lumber that can be encountered on the market.
We calculate the mass using a calculator, according to the formula M = V * ρ, kg, where:
- V- the volume of material required for the calculation, m3. In our case given value is 1 m3;
- ρ is the density of wood, kg / m3. For freshly cut pine, the value is 820 kg / m3.
Substituting into the formula, we get:
- M = 1 * 820 = 820 kg.
Similarly, knowing the density of the material, you can calculate: how much a cube of a larch board weighs:
- M = 1 * 940 = 940 kg.
And this means: no matter what size the edged board:
- 150x150x6000;
- 25x100x6000;
- 25x150x6000;
- 50x150x6000.
Their weight in one cube will be approximately equal, the main thing is that the composition of the wood, as well as the moisture indicator, remain unchanged, only the number of boards will differ.
The question arises, how much does a cube of a dry board of the same pine weigh? This state of wood is accepted when its moisture content is up to 20%. At the same time, the density is 520 kg / m3.
- M = 1 * 520 = 520 kg.
The difference in weight of one cube between pine natural moisture and dry will be - 300 kg! But for construction, not 1 m3 is purchased, but for example 100 or 500. Accordingly, the carrying capacity of the vehicle increases by 30 or 50 tons!
Therefore, when choosing lumber, it is important to know the moisture content of the board. In order not to make a mistake in the choice of transport or the number of flights required to transport the entire timber.
The wood was used in construction works ah from ancient times. Of course, because this material is still very popular due to the presence of excellent technical characteristics... Wood, in itself, is natural material structured type, consisting of wood cells and pericellular voids, which in turn does not at all guarantee that one part of the wood will be equal to another of identical size. Therefore, so often, in the process of work, the question arises of calculating the required amount of this material and such parameters as: the weight of the wood as a whole and the weight of a cube of wood.
| Wood species | Moisture percentage,% | ||||||||||
| Fresh | 100 | 80 | 70 | 60 | 50 | 40 | 30 | 25 | 20 | 15 | |
| Larch | 940 | 1100 | 990 | 930 | 880 | 820 | 770 | 710 | 700 | 690 | 670 |
| Poplar | 700 | 760 | 690 | 650 | 610 | 570 | 540 | 500 | 480 | 470 | 460 |
| Beech | 960 | 1110 | 1000 | 950 | 890 | 830 | 780 | 720 | 710 | 690 | 680 |
| Elm | 940 | 1100 | 1100 | 930 | 880 | 820 | 770 | 710 | 690 | 680 | 660 |
| Oak | 990 | 1160 | 1160 | 990 | 930 | 870 | 820 | 760 | 740 | 720 | 700 |
| Hornbeam | 1060 | 1330 | 1330 | 1130 | 1000 | 990 | 930 | 860 | 840 | 830 | 810 |
| Norway spruce | 740 | 750 | 750 | 640 | 600 | 560 | 520 | 490 | 470 | 460 | 450 |
| Walnut | 910 | 1000 | 1000 | 850 | 800 | 750 | 700 | 650 | 630 | 610 | 600 |
| Linden | 760 | 830 | 830 | 710 | 660 | 620 | 580 | 540 | 540 | 530 | 500 |
| White acacia | 1030 | 1330 | 1330 | 1190 | 1060 | 990 | 930 | 860 | 840 | 830 | 810 |
| Alder | 810 | 880 | 880 | 750 | 700 | 660 | 620 | 570 | 560 | 540 | 530 |
| Maple | 870 | 1160 | 1160 | 990 | 930 | 870 | 820 | 760 | 740 | 720 | 700 |
| Common ash | 960 | 1150 | 1150 | 930 | 920 | 860 | 800 | 740 | 730 | 710 | 690 |
| Siberian fir | 680 | 630 | 630 | 540 | 510 | 470 | 440 | 410 | 400 | 390 | 380 |
| Scots pine | 820 | 850 | 850 | 720 | 680 | 640 | 590 | 550 | 540 | 520 | 510 |
| Caucasian fir | 720 | 730 | 730 | 620 | 580 | 550 | 510 | 480 | 460 | 450 | 440 |
| Cedar pine | 760 | 730 | 730 | 620 | 580 | 550 | 510 | 480 | 460 | 450 | 440 |
| Birch | 870 | 1050 | 1050 | 890 | 840 | 790 | 730 | 680 | 670 | 650 | 640 |
| Aspen | 760 | 830 | 830 | 710 | 660 | 620 | 580 | 540 | 530 | 510 | 500 |
Depending on the type of construction work, wood needs to be measured differently. For the weight of m3 of wood, the density of the material is of particular importance, respectively, for correct decision of the questions posed, it is necessary to determine the density value. There are two types of density:
Specific gravity (density of woody substance)
Volumetric weight (density of a structured physical body)
Wood substance is a mass of solid wood materials without natural voids. This view density is measured in laboratory conditions, as it requires additional measurements that are not feasible under normal conditions. For each wood of all types and species of trees, this value is constant and is 1540 kg / m3.
The density of the wood itself is quite easy to determine under normal conditions. To do this, it is enough to weigh a piece of wood and measure its volume. Process the obtained data with standard arithmetic operations according to the following formula: Y = M / O, where Y is the specific gravity of the tree, M is the mass of wood, O is the occupied volume.
Table of volumetric weight of 1m3 of wood depending on moisture content.
The density of the woody substance, as already mentioned, is a constant. However, wood has a multicellular fibrous structure of a complex type. Wood-based walls play the role of a frame in the wood structure. Accordingly, for each tree species and species, the cell structures, shapes and sizes of cells vary, as a result of which the specific gravity of the tree will be different, as well as different weight m3 of wood.
Also, moisture plays an important role in changing the specific gravity of wood. Due to the structure of this material, with increasing humidity, the density of wood also increases. However, this rule does not apply to the density of the woody substance.
Below is the specific gravity of wood. The table is compiled depending on the moisture content of the material and is calculated such an indicator as the weight of 1m3 of wood.
- Groups of tree species
- Dependence on humidity
- Impact on wood quality
The density of wood is one of the main characteristics of a cubic meter of material, which is taken into account when calculating structures, choosing raw materials for the production of various products. The concept means the ratio of the mass of the material to the measured volume.
What can be the density of the forest
Different tree species have approximately the same composition, therefore, in dry form, the absolute specific gravity for all will be conditionally the same. Its average value is 1.54 (dimensionless). But in the table of wood density for different species, their numbers are given. The fact is that it is almost impossible to measure the absolute parameter in a completely dry state. To do this, it is necessary to completely get rid of moisture in the test sample, eliminate air voids. In practice, as it turned out, it is difficult to fix the parameter, and it is also unsuitable for calculations.
To determine the density of lumber, the calculation of its specific gravity is more suitable.
It is influenced by:
- humidity;
- porosity of rocks.
The specific gravity of wood has the form of the average value of density calculations in its different states. In sources, this indicator may differ slightly. The difference is due to the change in the moisture level inside the trunk. To avoid confusion, we present a table with the average values of the specific gravity at each individual moisture level of different wood species in ascending order of indicators.
Wood density table with different moisture content (kg / m 3)
Groups of tree species
Typically, the tabular value of the density of timber and other sawn timber is measured at a moisture content of 12%. Depending on the value obtained, tree species are divided into 3 groups:
- With a low bulk density (less than 540 kg / m 3). These include coniferous trees: pine, spruce, fir, cedar and some deciduous. These are all types of alder, poplar, linden, aspen, chestnut.
- With an average specific gravity of 550-740 kg / m 3: beech, elm (elm), larch, all types of maple, mountain ash, apple, ash.
- WITH high level density over 750 kg / m 3: birch, oak (araksin, chestnut-leaved), hornbeam, dogwood, pistachio.
Of course, this is an incomplete list of breeds. According to the indicated values of the density of wood in the table, you can determine the belonging of the species to the group.
Dependence on humidity
Any lumber contains water. Its amount mainly determines the density of the timber and other raw materials: the more moisture in the product, the higher the weight in the measured volume.
The specific gravity of wood in the table is given in average values, since the amount of moisture in one volume is constantly changing - this is a relative value.
Changes are due to:
- external weather conditions(rain, fog, snow);
- anthropogenic factor (getting wet due to human activity).
Thus, a completely dry board practically does not exist. The moisture content of the wood is always above 0%... You can determine this indicator using a special device - a moisture meter.
Impact on wood quality
The average specific gravity is the main characteristic of raw materials in the calculations, since the value contains the average assessment of the tests of sawn timber in different states of water saturation.
According to the laws of physics, the calculated density is directly related to the strength of the material: the higher the specific gravity of the volume of the product, the greater the load it can withstand. This rule also applies to wood.
Let's take an example:
- Oak has a high specific gravity and is famous for its reliability and durability. It has almost no empty pores, the entire volume is filled with strong wood fibers and moisture. Made from oak bearing structures houses and industrial facilities... Wood with a high specific gravity is tough, practically does not bend.
- Cedar and birch beams are distinguished by their low volumetric weight, therefore they are not used to create load-bearing elements of the frame of structures. These breeds are more suitable for finishing works where the load on the products is minimal. Wood with low porosity is flexible and lends itself to bending.
Dependence of density and thermal conductivity
This indicator is important for choosing a tree when harvesting firewood. The dependence is direct: the higher the density index, the more fuel in the lumps, the longer they will burn. Wood species with high value the ratio of mass to volume is called solid fuel... They burn for a long time, give good heat, but due to their dense structure, it is difficult to prick. The advantage of firewood and fuel from light woods is their pliability in sawing and felling, but they have a relatively small amount of energy. The logs will burn for a much shorter amount of time.
When working with lumber, it is often necessary to know what the weight of wood... Let's figure out how much a cube of wood weighs and how to determine this value?
Wood mass - why measure it?
First, let's figure out what this value is for at all - weight of wood and how important this indicator is.
The weight of the wood plays an important role in construction:
- Firstly, this indicator makes it possible to determine the weight finished structure, whether its floor or foundation will withstand;
- secondly, a specific mass of sawn timber is needed when determining the method of transportation, it helps to determine how much transport will be able to move this or that amount of wood;
- thirdly, before buying the material, you need to figure out how much a cube of a bar weighs, how much a cube of a lining or board weighs. All these materials are sold not by the piece, but in cubic meters. Therefore, knowing how to determine the weight of the material is necessary at least so that unscrupulous sellers cannot deceive you. Well, in order to provide for yourself the required amount material, this also does not hurt. Finding yourself in a situation where at the most inopportune moment you realize that there is not enough material is quite unpleasant, just like the situation when, after the completion of construction, it is discovered that there is still a whole trailer of no longer needed wood;
- fourthly, such an indicator as weight of wood important when determining the storage location of the material. Knowing how much wood takes up, you can easily determine what size storage space is needed.
How to determine the weight of a cube of wood?
The mass of wood depends on several parameters:
Wood species. Wood species are divided into light ones weighing up to 500 kilograms (this includes conifers), medium - weight up to 650 kilograms (for example, birch or ash) and heavy - weight over 700 kilograms (the most popular representative is oak).
The moisture level is also divided into several levels: dry wood - moisture up to 15%, air-dry - moisture up to 20%, wet - up to 45%, and wet - moisture above 46%. That is, with different moisture content, even the wood of the same tree will have a different mass and with the weight of different species it will differ even with the same moisture level.
The very concept of wood mass includes several measured parameters that are convenient to use in one case or another:
- the specific gravity of wood is a parameter that shows how the cube of wood and the cube of water are related. Determine the specific gravity of lumber without taking into account moisture and wood species, that is, this indicator will be averaged for any tree. The specific gravity is used both to determine the actual cubic capacity of the tree and to determine the volume of the stored board. The specific gravity of wood is convenient to use for companies involved in the transportation of material, in this case there is no need to measure moisture and other values for each individual species, because sometimes several types of wood are transported, and they can have completely different moisture, calculating the total weight of such materials will take a lot of time , therefore, it is easier to use a ready-made average.
- void ratio - this indicator, which helps to determine the mass of stored lumber. Stored timber, especially if it is untreated or has non-standard shape, forms voids among themselves, which significantly affect the determination of the total mass of such material. If you do not take into account the void ratio in the calculations, you can get only very approximate values. What is the formula for calculating the weight of wood, taking into account the void ratio? If we take all the stored material as 100%, then the voids will take about 20%, respectively, the remaining 80% is wood. The void ratio is 0.8. Suppose you have 10 cubic meters of area occupied by a stored board, multiply 10 by a factor of 0.8 and we get that the wood in the room is 8 cubic meters.
Reference values - on the Internet, and just in everyday life, there are certain stable values for the weight of wood and products from it. This value is easy to use when purchasing. It is enough just to know the type of wood from which, for example, the lining is made. You open the table and see how much one cubic meter of alder or oak timber lining weighs. This makes it very easy to check if the lumber sellers are cheating on you.
Volumetric weight of a cube of wood - an indicator of volumetric weight is often equal to the values of density of wood. To determine it, a universal moisture indicator is taken - 20% and a fixed density value is determined. All measured data are entered in special tables and are in free access in the Internet. Volumetric weight is also called GOST. The volumetric weight of wood is used to determine the parameters of both an untreated board and an untreated board. This value is very versatile and allows you to compare the weight of different species, but subject to the same moisture content.
The weight of a cubic meter of wood of different moisture content
Below is a table for your attention, which shows the values of the weight of wood of different species at different levels of moisture.
| Breed | Humidity, % | |||||||||||
| 10 | 15 | 20 | 25 | 30 | 40 | 50 | 60 | 70 | 80 | 90 | 100 | |
| Beech | 670 | 680 | 690 | 710 | 720 | 780 | 830 | 890 | 950 | 1000 | 1060 | 1110 |
| Spruce | 440 | 450 | 460 | 470 | 490 | 520 | 560 | 600 | 640 | 670 | 710 | 750 |
| Larch | 660 | 670 | 690 | 700 | 710 | 770 | 820 | 880 | 930 | 990 | 1040 | 1100 |
| Aspen | 490 | 500 | 510 | 530 | 540 | 580 | 620 | 660 | 710 | 750 | 790 | 830 |
| Birch: | ||||||||||||
| - fluffy | 630 | 640 | 650 | 670 | 680 | 730 | 790 | 840 | 890 | 940 | 1000 | 1050 |
| - ribbed | 680 | 690 | 700 | 720 | 730 | 790 | 850 | 900 | 960 | 1020 | 1070 | 1130 |
| - Daurian | 720 | 730 | 740 | 760 | 780 | 840 | 900 | 960 | 1020 | 1080 | 1140 | 1190 |
| - iron | 960 | 980 | 1000 | 1020 | 1040 | 1120 | 1200 | 1280 | - | - | - | - |
| Oak: | ||||||||||||
| - petiolate | 680 | 700 | 720 | 740 | 760 | 820 | 870 | 930 | 990 | 1050 | 1110 | 1160 |
| - eastern | 690 | 710 | 730 | 750 | 770 | 830 | 880 | 940 | 1000 | 1060 | 1120 | 1180 |
| - Georgian | 770 | 790 | 810 | 830 | 850 | 920 | 980 | 1050 | 1120 | 1180 | 1250 | 1310 |
| - Araksin | 790 | 810 | 830 | 850 | 870 | 940 | 1010 | 1080 | 1150 | 1210 | 1280 | 1350 |
| Pine: | ||||||||||||
| - cedar | 430 | 440 | 450 | 460 | 480 | 410 | 550 | 580 | 620 | 660 | 700 | 730 |
| - Siberian | 430 | 440 | 450 | 460 | 480 | 410 | 550 | 580 | 620 | 660 | 700 | 730 |
| - ordinary | 500 | 510 | 520 | 540 | 550 | 590 | 640 | 680 | 720 | 760 | 810 | 850 |
| Fir: | ||||||||||||
| - Siberian | 370 | 380 | 390 | 400 | 410 | 440 | 470 | 510 | 540 | 570 | 600 | 630 |
| - white-haired | 390 | 400 | 410 | 420 | 430 | 470 | 500 | 530 | 570 | 600 | 630 | 660 |
| - whole-leafed | 390 | 400 | 410 | 420 | 430 | 470 | 500 | 530 | 570 | 600 | 630 | 660 |
| - white | 420 | 430 | 440 | 450 | 460 | 500 | 540 | 570 | 610 | 640 | 680 | 710 |
| - Caucasian | 430 | 440 | 450 | 460 | 480 | 510 | 550 | 580 | 620 | 660 | 700 | 730 |
| Ash: | ||||||||||||
| - Manchu | 640 | 660 | 680 | 690 | 710 | 770 | 820 | 880 | 930 | 990 | 1040 | 1100 |
| - ordinary | 670 | 690 | 710 | 730 | 740 | 800 | 860 | 920 | 980 | 1030 | 1090 | 1150 |
| - sharp-fruited | 790 | 810 | 830 | 850 | 870 | 940 | 1010 | 1080 | 1150 | 1210 | 1280 | 1350 |
Irina Zheleznyak, Special correspondent of the Internet edition "AtmWood. Wood-Industrial Bulletin"
When designing various kinds wooden structures often used and such an indicator as the weight of the lumber from which they are supposed to be made. It would seem that such information can be obtained from specialized reference books. However, in such literature, unfortunately, only the weight of 1 m 3 of a bar or, for example, a board, is often indicated. Lumber is often purchased not by cubic meters, but simply by the piece.
The length of the timber sold by woodworking workshops can be different. But most often, such enterprises sell 6 m of lumber to the population. So what, for example, can be the weight of a timber of natural moisture 150x150x6000 mm? To find out, you will have to do some simple independent calculations.
What determines the weight of lumber
It is clear that the more moisture the timber contains, the heavier it will be. However, the weight of such sawn timber depends not only on this factor. When performing calculations, in this case, it is imperative to take into account the characteristics of the wood species itself. Indeed, for example, oak timber will in any case be heavier than birch lumber.
What is natural moisture
So how do you calculate your weight wooden beam natural humidity 150x150x6000 mm of a particular breed? It's actually not too difficult to do such calculations. However, before proceeding with the calculations, it is still worth deciding on the concept of "natural moisture".
In construction and in the manufacture of various kinds of products, only wood with a moisture content of no more than 12-15% is used. And even such boards and timber are, in most cases, additionally dried for some time before use.
The moisture content of only sawn wood will, of course, be very high. In any case, 12-15% of its figure will significantly exceed. It is this humidity that is commonly called natural. That is, we ultimately need to find out the weight of a wooden bursa of a standard length with a section of 15x15 cm, made of freshly sawn wood.
We take into account the breed
The basis for performing such an operation should be taken from the table of lumber weight in cubic meters.
Calculations are performed in this case as follows:
find out the number of bars of a given length and section in 1 m 3;
by simple division calculate the mass of one such unit of lumber.
One cubic meter of timber having dimensions of 150x150x6000 mm, thus, will contain 1: 0.15: 0.15: 0.15: 6 = 7.4 pieces. To find out the weight of the beam, in this case you need:
see the weight of a cubic meter for a given specific type of wood;
divide this parameter by the number of beams per cubic meter.
For example, with a moisture content of 15%, 1 m 3 of pine sawn timber weighs, according to the table above, 440 kg. That is, the calculation in this case will look like this:
440 / 7.4 = 59.5 kg.
It is also easy to determine that the weight of a timber 150x150x6000 mm from larch of the same moisture content will be equal to 90.5 kg. For aspen, this figure will be 67.6 kg.
Instructions for calculating the weight of a bar of natural moisture 150x150x6000 mm
Thus, the weight of lumber of a given moisture content is not too difficult to find out. To do this, you just need to solve two simple mathematical examples... But what will be the weight of the timber of natural moisture 150x150x6000 mm? In order to determine this, among other things, you need to know the very last indicator for a particular type of wood.
This information can also be obtained from special tables. So, for example, the natural moisture content of pine is 60-100%, larch - 50-70%, birch - 70-90%. These parameters should be taken in this case to calculate the weight. In this case, for obvious reasons, it will be impossible to make accurate calculations.
So, how much does a timber 150x150x6000 mm of natural moisture weigh? Given the data in the table above:
pine beams of such dimensions will weigh from 580 / 7.4 = 78.3 (60%) to 730 / 7.4 = 98.6 (100%) kg;
the weight of a timber of natural moisture 150x150x6000 mm made of larch will vary from 820 / 7.4 = 110.8 kg to 930 / 7.4 = 125.7 kg.
In the same way, you can calculate beams of such dimensions of natural moisture for any other rock.
Specific gravity
There are only two types of wood density:
volume weight(the density of the physical body of wood itself);
specific directly to wood fibers).
Above, we considered a method for determining the volumetric weight of a bar 150x150x6000. Natural moisture or given in such calculations - the indicator is important. Indeed, in this case, the weight also depends on the amount of moisture contained in the wood structure. But if desired, the specific density index can be calculated for the beams.
This can be done using the table above. Calculations in this case will be carried out without taking into account humidity. That is, to calculate, you need to find the number of beams of a certain size in a cubic meter and simply divide the indicator from the table by the resulting number.
Thus, for pine 520 / 7.4 = 70.3 kg is the specific weight of the timber 150x150x6000. Natural humidity - permissible operating or any other - in this case is not taken into account in any way.