For the manufacture of various building materials made of wood (lining, boards, slats, timber) material with natural moisture is used. However, according to the requirements of GOST and building regulations Raw wood floorboards must be dried before installation. This indicator determines how much a cube of natural moisture board weighs. Although the price of the material is charged for its volume, the weight of the board with natural moisture is important when transporting products. We will tell you how much a cube of natural moisture board of different types weighs.
Concept of material moisture
Before we tell you how much natural moisture edged boards and other lumber weigh, you need to understand the basic concepts. For the production of tongue and groove, terraced, planed and edged boards different types of wood are used. Each rock has its own specific hygroscopicity, that is, the ability to absorb moisture from the air.
Depending on the absorption of moisture, porosity and the structure of cell membranes, each type of wood has its own absolute humidity. The maximum value of this indicator is 30.
In addition, a board with natural humidity can absorb water through direct contact with it during precipitation or when the room is flooded. Dampness in the room also causes wood to absorb moisture. If ambient air becomes very dry, it gives off moisture.
Important! Most often, moisture loss occurs through the ends of the product.
The normal process of wood absorbing and releasing moisture is called “breathing.” Equilibrium humidity is a condition in which there is a balance of water between environment And internal space wood
The indicator of natural saturation with water depends on the location of the fibers in the structure. Moisture evaporates faster in the longitudinal direction of the fibers, rather than in the transverse direction. That is why a floor made from planks of natural moisture releases moisture faster at the ends of the floorboards.
To understand what it is batten ordinary humidity, you need to understand the concept of absolute and relative humidity:
- Relative saturation Moisture is the percentage of its mass in wood to the mass of the wet product.
- Absolute indicator always more relative. This is a percentage expression of the ratio of the mass of moisture in wood to the weight of ordinary dry material.
Important! Because hygroscopic intracellular fluid collects in the cell walls, it is more difficult to remove. In this regard, hygroscopic moisture has a greater effect on the geometry of the board, its weight and characteristics.
The weight of the edged board of natural moisture also depends on the unbound free liquid in the material, which collects in the intercellular spaces and inside the cells. Such moisture evaporates quickly and does not affect the characteristics of the product.
Natural moisture content is the moisture content in freshly cut wood that has not been dried. This non-standardized indicator can be in the range of 30-80 percent. The weight of 1 m3 of edged boards with natural moisture content depends on:
- the conditions in which the tree grows;
- the season when the sawing was done (winter wood is less saturated with moisture than that which was cut in the summer season).
Dependence of board weight on moisture
If you need a board with natural moisture, the price depends on the weight of the cube of material and its moisture saturation:
- semi-dry products have a humidity of 18 to 23 percent;
- a raw product with a moisture content of more than 23% is the cheapest - from $30 per cubic meter;
- dry edged board with humidity within 12-18 percent costs $40-50 per cubic meter;
- dry lumber with a humidity of 6-12 percent are the most expensive - from $60 per m³.
Depending on the dampness, the weight of the material also changes. For example, a cube of wet oak floorboards weighs 990 cwt. If the material is dried to a moisture content of 10%, then the mass of the cube will decrease to 0.67 tons. But the price for dried lumber will increase.
The increase in price depending on moisture saturation is justified by the fact that the characteristics of the product also increase:
- dried wood has stable geometric dimensions;
- it is resistant to rotting;
- the material is durable and flexible;
- wood is quickly and easily processed;
- ensures strong fixation by adhesive method;
- the product will last longer.
Attention! Damp wood is susceptible to mold, rot and warping. Ideally, the moisture content of the lumber is brought to the level at which shrinkage and swelling of the wood stops. That is why the cost of such products is the highest.
How much does a cube of boards from different types weigh?
The weight of a cube of material is directly related to the type of wood from which it is made:
- Oak board with natural humidity weighs 990 c/m³. A cube of dried wood weighs 670 centners.
- Wet pine floorboards weigh 820 c/cu.m. The dried elements have a weight of 470 c/m³.
- Cube of boards damp spruce wood weighs 760 c, and a dried board weighs 420 c.
- Products made from wet larch have a weight of 940 c/cu. A cube of dry larch weighs 630 c.
- Birch lumber undried ones weigh 870 c/m³, and dry ones weigh 600 c/m³.
- Aspen floorboards from wet wood - 760 c/cubic meter, and dried wood - 470 cbm.
- Alder wood cube after cutting it weighs 810 quintals, and the dried material weighs 490 quintals.
Why is it necessary to know the weight of a cubic meter of wood?
Since the manufacturer charges the price for lumber depending on the type of wood, moisture content and volume, the weight of the material is not taken into account. This indicator will be needed when transporting lumber, since the choice of vehicle and the cost of transportation depend on it.
Also, the weight of wood is taken into account when calculating loads on building construction. As a rule, an ordinary consumer does not need such a calculation. It is done by designers and planners at the project development stage.
Artificial and natural drying
Natural drying of lumber is very slow and stretches for for a long time. However, this drying process is considered the most gentle, since cracks and other deformation defects do not appear in the wood. With aggressive chamber drying there is a high probability of cracking and deformation of the lumber.
Important! Natural drying is carried out in a special well-ventilated place, which is reliably protected from atmospheric moisture and direct sunlight.
The humidity of freshly cut wood reaches 50-80%. With natural drying, this figure drops to 18-22 percent. This drying method is the easiest to organize, since it does not require the use of special equipment and compliance with certain rules. temperature regime. Flaws natural drying– duration of the process and low intensity.
Artificial drying in chambers proceeds much faster. At the same time, the humidity indicator is reduced to 10-18 percent. During the drying process, you can adjust the temperature and control the entire process. Products placed in stacks are placed in the chambers, each of which contains lumber of the same thickness and species.
Advantages of artificial drying:
- protection against mold and rot;
- You can dry wood treated with special protective compounds;
- speed of drying (usually it takes a week).
The Drova72 company conducted an experiment, we weighed 1 folded cube (folder) of birch chopped wood, natural humidity, ~50%. We will discuss the results of this experiment in more detail below.
This experiment in no way claims to be - "scientific" or "100% objective", rather something between information from the Internet and laboratory research. But nevertheless, this is the first step on the path to truth and objectivity.
Next time we will repeat the experiment and try to find a moisture meter, as well as film the whole process on video.
In short, the results
At humidity ~50% and log length ~50cm:
- 1 folding cube weighs ~561 kg;
- 1 tight cubic cube weighs ~790 kg.
In the text below, we reveal in detail the essence of the experiment. The calculation was made based on information from GOST 3243-88 and the sawmill handbook.
Why do we need this?
A small retreat
The volume of firewood in storage meters is measured by multiplying the length, width and height of the woodpile. But the concept of “1 folded cube of firewood” is quite vague, because... firewood in the woodpile can be stacked with different packing densities and there is no GOST or regulation that would explain what “laying density” is and how to measure it. That is, the same amount of firewood (1 conventional storage meter) can be stacked from ~0.7 to ~1.3 foldometers, depending on the packing density and condition of the logs (their curvature, the presence of knots).
For clarity, look at the photo below. It is obvious that the firewood on the right is stacked thoroughly and the number of logs in such a woodpile is greater than in the one on the left. In both cases, the volume of firewood in the storage meters will be the same, but the mass is different. Those. in fact, the amount of firewood in the photo on the left is less. 
In the photo above, please ignore different type firewood, this image shows the density of firewood stacking in a woodpile.
Specifics
Sometimes our clients and I have disagreements regarding the volume of firewood in storage meters. We brought the firewood for stacking in one volume, the client transferred the firewood to his woodpile, measured it, and the volume turned out to be less than originally stated.
In the example above, disagreements almost always arise due to packing density. So we decided weigh 1 folded cube of birch firewood, and compare its weight (mass) with the data, which are presented in GOST 3243-88 and in the Handbook of Sawmilling, Moscow, Timber Industry Publishing House, 1980.
By comparing the weight of our firewood storage meter with data from the above sources, we will understand whether we are packing the firewood tightly enough into the car before delivering it to the buyer.
Sequencing:
- First we will put 1 folding cube in the woodpile.
- Let's weigh this cube on the scales.
- We compare the resulting weight with data from GOST 3243-88 and the Sawmilling Handbook.
By different sources, the humidity of freshly cut birch can vary from 60 to 80%. We purchase firewood birch, which was harvested (cut down) 1 to 4 months ago from the moment it was brought to us for subsequent processing. The humidity of birch is on average 40-50%. We will make calculations based on 50% humidity.
In the sawmill reference book, the weight of a dense cube of ordinary birch at a humidity of 50% is 790 kg. To convert the weight of a storage meter into a dense cube (or vice versa), you need to apply a coefficient. We will take it from GOST 3243-88, with log lengths up to 0.5 meters split hardwood - coefficient is 0.71.
790 * 0.71 = 560.9 kg
Those. The mass of our split birch firewood storage meter must be at least 561 kg.
We weigh
Conclusions and comments
First of all, we wanted to test ourselves, because... Sometimes doubts arose about honesty towards our firewood buyers. Now the doubts are dispelled. Our stacking density and volume of firewood in stacked cubic meters meets the necessary requirements.
If we turn again to the sawmill reference book (Note 1), it is obvious that the weight of 1 folded cube at a humidity of 50% will not always be 560.9 kg, because the weight of one dense cube is 790 kg - this is an average value and can range from 553 kg to 1027 kg. And, therefore, 1 storage meter of birch chopped firewood (taking into account the coefficient of 0.71) can weigh from 392kg to 729kg. This is probably due to the different densities of trees and logs.
Of course, this experiment cannot be considered 100% objective, because At a minimum, a moisture meter is needed to determine humidity. We can have a forest different humidity because There are many suppliers and the procurement and delivery times are different for everyone; accordingly, forest moisture can vary from 30 to 60%.
If you have any suggestions or comments about this material- please write to our email: mail@site.
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 wood delivery services, but it happens that this is not possible. And this question has to be decided by the buyer himself: what kind of car should be ordered in order to bring required amount scaffolding at the construction site?
Features of lumber
Even if the amount of wood in cubic meters is known, then the choice of machine in terms of carrying capacity will still need to be calculated. Even knowing how much a cube of dry board weighs, the weight of a cubic meter of material on the market can vary significantly. And the reason for this will not only be the type of tree, for example: pine or spruce, birch or cedar, but also the location 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 of a unit of cubic meter of the same wood 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 density of the material in one cube will be different. It is not possible to stack the round timber 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 vehicle, you need to focus on transporting the maximum possible weight of cargo. This means you need to find out how much a cube of edged pine boards of natural moisture weighs? Since this is the state of the tree at the time of its felling, and therefore the maximum humidity and density.
Indicators affecting the weight of lumber
Wood moisture content is very important indicator, which you need to pay attention to. When it is high, the tree swells, and when it is low, on the contrary, it dries out. All construction works It is recommended to use already dried lumber, in which the moisture content does not exceed 15-20%. Otherwise, the installed damp wood, as it dries over time, will change its geometric dimensions (shrink) 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, and retains its properties for a long time. construction qualities. Before drying, the remaining bark is removed. This is necessary for uniform drying and to prevent damage by insects (bark beetles).
Forest drying is carried out by specialists outdoors. The timber is stacked on spacers between the rows so that air can pass freely and dry the boards on all sides. It is advisable to locate the drying area in a place where the material is not exposed to direct Sun rays, 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 you can encounter on the market.
We will calculate the mass using a calculator using the formula M=V*ρ, kg, where:
- V is the volume of material required for calculation, m3. In our case given value is 1 m3;
- ρ—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 larch board weighs:
- M=1*940=940 kg.
This means: no matter what size the edged board is:
- 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 content, remain unchanged, only the number of boards will differ.
The question arises, how much does a cube of dry board of the same pine weigh? This state of wood is accepted when its humidity is up to 20%. In this case, the density is 520 kg/m3.
- M=1*520=520 kg.
The difference in the weight of one cube between pine with 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. So as not to make a mistake in the choice of transport or the number of trips required to transport the entire forest.
When designing various kinds wooden structures Often they use 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 timber or, for example, boards is often indicated. Lumber is often not purchased cubic meters, but just piece by piece.
The length of timber sold by woodworking workshops may vary. But most often such enterprises sell 6 m of lumber to the public. So what, for example, can be the weight of timber with natural moisture content of 150x150x6000 mm? To find out, you'll have to do a few simple things. independent calculations.
What determines the weight of lumber?
It is clear that the more moisture contained in the timber, the heavier it will be. However, the weight of such lumber depends not only on this factor. Performing calculations in in this case The characteristics of the wood species itself must also be taken into account. After all, for example, oak timber will in any case be heavier than birch lumber.
What is natural humidity
So, how do you calculate weight? wooden beam natural humidity 150x150x6000 mm of this or that breed? Making such calculations is actually not too difficult. However, before starting calculations, it is still worth defining the concept of “natural humidity”.
In construction and in the manufacture of various types 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 humidity of only cut wood will, of course, be very high. In any case, its figure will significantly exceed 12-15%. It is this kind of humidity that is usually called natural. That is, we ultimately need to find out the weight of a standard-length wooden beam with a cross-section of 15x15 cm, made from freshly sawn wood.
We take into account the breed
When performing such an operation, information from the table of lumber weights in cubic meters should be taken as a basis.
Calculations in this case are performed as follows:
find out the number of beams of a given length and cross-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 will thus 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:
look at the weight per cubic meter for this particular type of wood;
divide this parameter by the number of beams per cubic meter.
For example, with a humidity of 15%, 1 m 3 of pine lumber 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 150x150x6000 mm larch beam 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 timber with natural humidity 150x150x6000 mm
Thus, it is not too difficult to find out the weight of lumber of a given moisture content. To do this, you just need to solve two simple mathematical examples. But what will be the weight of a beam of natural humidity 150x150x6000 mm? In order to determine this, among other things, you need to know the last indicator itself for a particular type of wood.
You can also obtain such information from special tables. So, for example, the natural humidity 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 beam of 150x150x6000 mm of natural humidity weigh? Taking into account the data in the table presented 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 larch timber with natural humidity 150x150x6000 mm will vary from 820 / 7.4 = 110.8 kg to 930 / 7.4 = 125.7 kg.
In a similar way, you can calculate beams of such natural moisture dimensions for any other rock.
Specific gravity
There are only two types of wood density:
volume weight(density of the physical body of wood itself);
specific wood fibers directly).
Above we discussed a method for determining the volumetric weight of timber 150x150x6000. Natural humidity or specified in such calculations is an important indicator. Indeed, in this case, the weight also depends on the amount of moisture contained in the wood structure. But if desired, you can also calculate the specific density index for beams.
This can be done using the table presented 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 certain size in 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 operational or any other - is not taken into account in this case.
- Tree species groups
- Humidity dependent
- Impact on wood quality
Wood density is one of the main characteristics of a cubic meter of material, which is taken into account when calculating structures and choosing raw materials for production. various products. The concept refers to the ratio of the mass of a material to the measured volume.
What is the forest density?
Different tree species have approximately the same composition, so in dry form the absolute specific gravity for all will be roughly the same. Its average value is 1.54 (dimensionless value). But the wood density table shows its own numbers for different species. The fact is that in a completely dry state it is almost impossible to measure the absolute parameter. To do this, it is necessary to completely get rid of moisture in the test sample and eliminate air voids. In practice, as it turned out, it is difficult to fix the parameter, and it is not suitable for calculations.
To determine the density of lumber, calculating its specific gravity is more suitable.
It is influenced by:
- humidity;
- rock porosity.
Specific gravity wood has the form of an average value of density calculations in its different states. This figure may vary slightly in sources. The difference is due to changes in the moisture level inside the trunk. To avoid confusion, we present a table with average specific gravity values at each individual moisture level for different wood species in ascending order.
Table of wood densities of different humidity levels (kg/m3)
Tree species groups
Typically, the table value of the density of timber and other lumber is measured at a humidity of 12%. Depending on the obtained value, tree species are divided into 3 groups:
- With low volumetric mass (less than 540 kg/m3). These include trees coniferous species: 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/m3: beech, elm (elm), larch, all types of maple, rowan, apple, ash.
- WITH high level density over 750 kg/m3: birch, oak (Araksin, chestnut-leaved), hornbeam, dogwood, pistachio.
Of course, this is an incomplete list of breeds. By specified values wood density in the table you can determine whether the species belongs to the group.
Humidity dependent
All lumber contains water. Its quantity mainly determines the density of 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 occur due to:
- external weather conditions(rain, fog, snow);
- anthropogenic factor (wetting due to human activity).
Thus, a completely dry board practically never happens. Wood moisture content is always above 0%. This indicator can be determined using a special device - a moisture meter.
Impact on wood quality
The average specific gravity is the main characteristic of raw materials when carrying out calculations, since the value contains an average assessment of lumber tests in different states 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 look at 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 rigid and practically does not bend.
- Cedar and birch beams have a low volumetric weight, which is why 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 plastic and bendable.
Relationship between density and thermal conductivity
This indicator is important for choosing a tree when preparing firewood. The relationship is direct: the higher the density index, the more fuel there is in the lumps, the longer they will burn. Tree 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 they are difficult to prick. The advantage of firewood and fuel from light tree species is their flexibility in sawing and cutting, but they have a relatively small energy reserve. The logs will burn for a significantly shorter amount of time.