Mass of wood in 1 m3. Volumetric and specific gravity of wood of all species

How much does a cube (cubic meter) of wood weigh?

The weight of a cubic meter of wood depends on the type of wood and humidity.

• The heaviest tree is snakewood (Piratinera guianensis, Brosinum guianensis, “snake tree”, “speckled tree”), its dry volumetric weight is 1300 kilograms per cubic meter.
• The lightest tree is balsa (balsa, ochrome pyramidal, “cotton tree”), its dry volumetric weight is from 130 kilograms per cubic meter.

The table shows data on the weight of a cubic meter (cube) of 170 different types of wood at a standard humidity of 12%.

• Wood type
• Weight of a cubic meter (cube) of wood in kilograms

Weight of wood - why measure it?

First, let's figure out why this value is needed - the mass of wood

and how important this indicator is.
The weight of wood plays a big role in construction:
- Firstly, this indicator makes it possible to determine the weight of the finished structure and whether its floor or foundation will support it;
- secondly, a specific mass of lumber is necessary when determining the method of transportation, it helps to determine how much volume transport can move a particular amount of wood; — thirdly, before purchasing the material, you need to figure out how much a cube of timber weighs, how much a cube of lining or board weighs. All these materials are sold not individually, but in cubic meters. Therefore, it is necessary to know how to determine the weight of the material, at least so that unscrupulous sellers cannot deceive you. Well, in order to provide yourself with the necessary amount of material, this will also 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 completion of construction, it is discovered that there is still a whole trailer of wood that is no longer needed; - fourthly, such an indicator as the mass of wood
is important when determining the storage location of the material. Knowing how much wood occupies, 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:

Tree species. Wood species are divided into light ones weighing up to 500 kilograms (this includes coniferous species), medium - weighing up to 650 kilograms (for example, birch or ash) and heavy - weighing over 700 kilograms (the most popular representative is oak).

The humidity level is also divided into several levels: dry wood - humidity up to 15%, air-dry - humidity up to 20%, wet - up to 45%, and wet - humidity above 46%. That is, with different humidity levels, even the wood of the same tree will have a different weight, and the weight of different species will differ even with the same level of humidity. 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 a cube of wood and a cube of water relate. The specific gravity of lumber is determined without taking into account moisture content and tree species, that is, this indicator will be averaged for any tree. Specific gravity is used both to determine the actual cubic capacity of the tree and to determine the volume of the stacked board. Specific gravities of wood are convenient to use for companies involved in transporting material; in this case, there is no need to measure humidity and other values ​​for each individual species, because sometimes several types of wood are transported, and they can have completely different humidity levels; calculating the total weight of such materials will take a lot of time , therefore it is easier to use a ready-made average value. — void ratio is an indicator that helps determine the mass of stored lumber. Stored wood, especially if it is untreated or has a non-standard shape, creates voids between itself, 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 only get very approximate values. What does the formula for calculating the weight of wood look like, taking into account the void ratio? If we take all the stored material as 100%, then the voids will occupy about 20%, respectively, the remaining 80% is wood. The void ratio will be 0.8. Let’s say you have 10 cubic meters of space occupied by stored boards, multiply 10 by a factor of 0.8 and get that there are 8 cubic meters of wood in the room.

Reference values ​​are available on the Internet, and in everyday life there are certain stable values ​​for the weight of wood and products made 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 lining made of alder or oak beams weighs. This makes it very easy to check whether lumber sellers are deceiving you.

Volumetric weight of a cube of wood - an indicator of volumetric weight is often equal to the density of wood. To determine it, a universal humidity indicator is taken - 20% and a fixed density value is determined. All measured data are entered into special tables and are freely available on the Internet. Volumetric weight is also called GOST. The volumetric weight of wood is used to define the parameters of both untreated boards and untreated boards. This value is very universal and allows you to compare the weight of different breeds, but subject to the same humidity.

Weight of a cubic meter of wood of different humidity

Below is a table that shows the weight of wood of different species at different humidity levels.

Irina Zheleznyak, Staff correspondent of the online publication “AtmWood. Wood-Industrial Bulletin"

It varies widely even for one type of wood. The values ​​of the density (specific gravity) of wood are generalized figures. The practical value of wood density differs from the average table value given and this is not an error.

Table of density (specific gravity) of wood depending on the type of wood

• The table shows the density of wood at a humidity of 12%.
• The table indicators are taken from the “Handbook of Masses of Aviation Materials” ed. "Mechanical Engineering" Moscow 1975
• Corrected 03/31/2014, according to the method: Kolominova M.V., Physical properties of wood: guidelines for students of specialty 250401 “Forest Engineering”, Ukhta: USTU, 2010
  Download (downloads: 710)

It is generally accepted to indicate the density (specific gravity) of wood depending on the type of wood. The indicator is taken to be the average value of the specific gravity, obtained by summarizing the results of repeated practical measurements. In fact, two wood density tables are published here, taken from completely different sources. A small difference in the indicators clearly indicates the variability of the density (specific gravity) of wood. When analyzing the wood density values ​​from the table above, it is worth paying attention to the differences between the indicators in the aviation reference book and the university manual. For objectivity, the value of wood density from both documents is given. With the right for the reader to choose the priority of the importance of the original source.

Particularly surprising is the table value of larch

- 540-665 kg/m3. Some online sources indicate the density of larch as 1450 kg/m3. It is not clear who to believe, which once again proves the uncertainty and unknown nature of the topic being raised. Larch is a fairly heavy material, but not so heavy that it would sink like a stone in the water.

The influence of humidity on the specific gravity of wood

Specific gravity of driftwood

It is noteworthy that with an increase in wood moisture content, the dependence of the specific gravity of this material on the type of wood decreases. The specific gravity of driftwood (humidity 75-85%) practically does not depend on the type of wood and is approximately 920-970 kg/m3. This phenomenon is explained quite simply. The voids and pores in wood are filled with water, the density (specific gravity) of which is much higher than the density of the displaced air. In terms of its value, the density of water approaches the density of , the specific gravity of which practically does not depend on the type of wood. Thus, the specific gravity of pieces of wood soggy in water is less dependent on its species than in the case of dry samples. At this point it is worth remembering that for wood there is a division of classical physical concepts. (cm. )

Wood Density Groups

Conventionally, all tree species are divided into three groups (according to the density of their wood, with a humidity of 12%):

1. Low density species
   (up to 540 kg/m3) - spruce, pine, fir, cedar, juniper, poplar, linden, willow, aspen, black and white alder, chestnut, white, gray and Manchurian walnut, Amur velvet;
2. Medium density species
   (550-740 kg/m3) - larch, yew, silver birch, downy, black and yellow, eastern and European beech, elm, pear, summer oak, eastern, swamp, Mongolian, elm, elm, maple, hazel , walnut, plane tree, rowan, persimmon, apple tree, common ash and Manchurian;
3. High-density species
   (750 kg/m3 and above) - white and sand acacia, iron birch, Caspian honey locust, white hickory, hornbeam, chestnut-leaved and Araksin oak, ironwood, boxwood, pistachio, hop hornbeam.

Lumber Tables

Below are detailed data that will immediately allow you to determine the required amount of lumber from 3 to 6 meters in length. It is very easy to use these tables - we find the required product sizes and see the amount of material and the volume of one element.

Helpful information.

Please note that these tables are approximate results. Doing your own calculations is more accurate. In addition, different manufacturers approach the stacking of lumber in their own way, so the density of the products can vary greatly. Therefore, make a reserve of about 10-20%, otherwise you will have to pay for delivery again.

Table 1.

The number of boards in 1 cubic meter of materials.

Table 2.

The amount of timber in 1 cubic meter of materials.

Table 3.

The amount of lining in 1 cubic meter of materials.

What affects weight?

The type of wood provides a certain density of the material. This indicator directly affects weight. Pine boards are quite dense and therefore heavy. There are other factors that matter.

• Humidity . A tree can absorb and retain water even from the air. Humidity will increase the weight of the board. It happens that the lumber has natural moisture or was poorly dried or stored incorrectly. All these factors will make it heavier. Therefore, even boards of the same type of wood can have different actual weights. Very wet boards are usually not used in construction. They shrink greatly and may even begin to rot.

• Damage by parasites. There are pests that settle inside the tree and eat holes in it. As a result, the material becomes more loose, the density decreases, and with it the weight. This fact allows you to immediately refuse to purchase low-quality pine boards. If a cube of material is significantly lighter than it should be according to standards, it means that parasites live inside.

• Internal defects . This factor is somewhat similar to the previous one. In this case, defects can be natural or acquired as a result of improper processing of lumber. The result is deplorable: the density of wood fibers decreases. This makes the lumber lighter.

Thus, the weight of a pine board depends on its moisture content and quality.

The first factor is changeable. Too wet lumber can be dried and used for its intended purpose. At the same time, low-quality boards cannot be used in construction; the decrease in density affects not only the weight. Such a board greatly loses strength and reliability, which means that a building made from it is unlikely to last long.

Mechanical properties

The mechanical characteristics of wood determine its ability to resist external influences. Mechanical properties include:

• strength;
• hardness;
• ability to bend;
• impact strength;
• ability to hold metal fasteners.

Indicators of mechanical properties are determined experimentally for individual wood species by load tests. For mechanical characteristics, wood humidity also plays a role, since the main physical indicators depend on it, therefore, for basic experiments, samples with a humidity of 12% are also taken.

But in practice, the effect of moisture on mechanical properties affects mainly during prolonged exposure, since deformation of wood occurs not only from mechanical damage. If improperly dried or stored, the fiber structure deteriorates, and along with it strength, hardness and other structural features. Therefore, when purchasing material, it is necessary to pay attention not only to its appearance, but also to storage conditions.

You will find a detailed analysis and examples of specific tree species in the full article.

Authorship of the article – Lenwood.ru

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. Different types of wood are used to make tongue-and-groove, decking, planed and edged boards. 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 the surrounding air becomes very dry, it releases 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 moisture is a condition in which there is a balance of water between the environment and the internal space of the 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 a normal humidity floorboard is, you need to understand the concept of absolute and relative humidity:

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:

Why do different types of wood have different densities?

This is the will of nature. Trees grow in both hot deserts and cool swamps, and try to survive in any conditions. In the middle zone, where it is only difficult in winter or in windy weather, plants have access to an abundance of nutrients in moist, moderately warm and well-fertilized soil. The tree, without denying itself anything, is saturated through the roots, the cambium grows quickly, and the fibers are filled with moisture. After drying, such wood loses a lot in weight and, accordingly, in density.

Plants in difficult climatic conditions have to accumulate vital substances inside the fibers. They learn to produce oils that protect them from drought and insects. Constant shortage and stress makes trees not only thrifty, but also slow growing. The minimal growth of cambium throughout the year makes the growth rings practically indistinguishable, and the lack of moisture leads to the appearance of oils in the fibers, which do not evaporate after drying.

The oiliness of some rocks can be felt with your fingers, and sometimes visually - for example, if you treat the surface of the bar with a solvent:

Different types of wood originated and took root where they were able to adapt to the conditions, and grow in close relationship with the surrounding flora and fauna. Trees detect any changes in the environment, responding to them with adaptation in the structure itself, so even within a breed, family, genus and species, plants can differ greatly from each other. Including density.

These rocks grow on the same continent in similar weather conditions, but under a microscope their structure is very different:

The effect of humidity on the weight of wood

The weight of wood does not always have the same value. What does it depend on? First of all, from the moisture content of the wood. If we compare, for example, oak and birch, it turns out that a cubic meter of oak weighs 700 kg, and a birch weighs 600 kg. But it could be different. Weighing a cubic meter of birch, we get 900 kg, and oak will show the same 700. Or in both cases it will be 700 kg. Why do we get such different numbers? In this case, the moisture content of the wood plays a role.

There are four degrees of humidity: dry (10-18%), air-dry (19-23%), damp (24-45%) and wet (above 45%). Thus, it turns out that different rocks with the same humidity have different weights, as in the first example above. If the humidity is not the same, then the weight may fluctuate in one direction or another. The standard humidity is 12%.

Table of volumetric weight of 1m3 of wood depending on humidity.

The density of wood matter, as already said, is a constant. However, wood has a multicellular fibrous structure of a complex type. Walls made of wood substance play the role of a frame in the structure of wood. Accordingly, for each tree species and species, the cellular structures, shapes and sizes of cells vary, as a result of which the specific gravity of the tree will be different, as well as the different weight of m3 of the tree.

Also, humidity plays a big 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 wood substances.

Below is the specific gravity of wood. The table is compiled depending on the moisture content of the material and is calculated using an indicator such as the weight of 1m3 of wood.

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 moisture content 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 a moisture content in the range of 12-18 percent costs $40-50 per cubic meter;
• dry lumber with a moisture content of 6-12 percent is 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.

Different density - different weight

Another factor that affects the weight of wood is its density. The highest density of iron and ebony wood is from 1100 to 1330 kg/m3. Boxwood and bog oak are close to them - 950-1100. For ordinary oak, beech, acacia, pear, and hornbeam, the density is about 700 kg/m3. It is even lower for pine, alder, and bamboo - 500 kg/m3. And the lowest is for cork wood, only 140 kg/m3.

The mass of wood depending on its density

Density of wood and wood materials

1. To determine the dead weight of structures, the density of wood of various species should be taken according to the following table:

Table 1

1. The density of freshly cut coniferous and soft deciduous wood should be taken equal to 850 kg/m³, hard deciduous wood - 1000 kg/m³.
2. The density of laminated wood should be taken as that of non-glued wood.
3. The density of ordinary plywood should be taken equal to the density of veneer wood, and bakelized plywood should be 1000 kg/m³.
4. The density of wood made from unidirectional veneer is 500-600 kg/m³, depending on the type of wood veneer.

Volume weight

If we are talking about a volume of wood close to one cubic meter, its weight is recalculated in tons. To be sure, blocks and stacks of wood are reweighed on truck scales that can withstand a load of up to 100 tons. Knowing the volume and type (wood species), the density group of a particular wood is determined.

• Low density - up to 540 kg/m3 - is characteristic of spruce, pine, fir, cedar, juniper, poplar, linden, willow, alder, chestnut, walnut, velvet, as well as aspen wood materials.

• The average density - up to 740 kg/m3 - corresponds to larch, yew, most birch trees, elm, pear, most oak species, elm, elm, maple, plane tree, some types of fruit crops, ash.

• Anything that weighs more than 750 kg per cubic meter refers to acacia, hornbeam, boxwood, ironwood, pistachio trees and hopshornbeam.

The volumetric weight in these cases is recalculated using the same average 12% humidity. So, for coniferous species, GOST 8486-86 is responsible for this.

Calculation features

It is necessary to accurately understand the weight of lumber at the time of purchase. This will ensure proper transportation and vehicle selection. And also, knowing the weight will allow you to clearly calculate the load that will be on the supporting structure or foundation after construction. There is a certain formula that allows you to find out the exact characteristics.

It is worth noting that the cube will have a different number of boards depending on their size. Edged boards with dimensions 50Х150Х6000 mm 22 pcs. in 1 m3. However, quantity and size do not play a role in calculating weight. This information is only important when purchasing.

Volumetric weight (Yw) is measured in g/cm3. It depends on the humidity and type of wood. It is usually calculated at normal humidity of 15%. To determine the formula, use Yw=Yo (100+W) / (100+ (Yo-Yw)).

Explanation of values:

• Yw – volumetric shrinkage;
• Yo – volumetric weight of completely dry wood with 0% moisture content;
• W – board moisture content.

You can also multiply length, thickness, width and density to calculate mass. The last parameter depends on humidity and is selected using a reference table. This method involves obtaining approximate data. You can also contact a specialist to calculate the weight. If you purchase lumber from a manufacturer, he can usually help resolve the issue.

Practical approaches and techniques

Often information about lumber is used in a specific form. For example, due to the complexity of measuring the characteristics of untreated wood, round timber and unedged boards, as well as for universal comparison of different species, the following indicators are used:

• volumetric weight, which essentially corresponds to density;
• specific gravity, showing the ratio of the mass of a cube of wood to a cube of water;
• void ratios during storage;
• reference examples.

The first indicator is used most often. The weight of a cube of wood is usually calculated based on the fixed density that a given species has at a known level of its humidity, as described above. This is the standard and most common approach. Thus, at 20% humidity, the volumetric weight of a cube of Scots pine is 450 kg/m³ (0.45 g/cm³), oriental oak is 730 kg/m³ (0.14 g/cm³), and so on.

When storing wood, it is necessary to take into account the void ratio.

Specific gravity is a ratio that applies to both actual cubic capacity and stockpiled wood that has voids. This indicator is convenient for carriers to use for transportation. It also refers to the ratio of the volumetric weight of a particular wood to the volumetric weight of water. Since the volumetric weight of water is 1000 kg, specific gravity is not only a useful tool for comparing the density of different species, but also indicates whether a given wood will sink or not. If the specific gravity of a cube of eastern oak at 20% is 730 kg, this means that it floats quite well, and iron birch at a humidity of 20% and above (1000-1020 kg) will sink.

The void ratio is used for storage. The volume of untreated wood, including freshly cut wood, is difficult to calculate, so the actual volume is calculated from the number of cubic meters multiplied by the void ratio. For example, if during storage only 80% of the space is occupied by wood, then this coefficient is 0.8, and from 20 storage meters you will get 20 * 0.8 = 16 cubic meters of wood.

Standards are used to compare the actual parameters of wood with the declared ones. This is how, for example, sellers are checked for honesty or the quality of wood.

The convenience and clarity of the indicators used in practice in calculations help to correctly and fully provide construction with supplies, as well as deliver them to the place of use. Therefore, knowledge of the basic properties of building materials is the key to timely and waste-free construction of buildings.

How is wood density measured?

Wood density is measured using a specific algorithm:

• The wood sample is kept to a moisture content of 12%
• The size of the sample and its weight are measured.
• Based on the obtained parameters, the volume of wood is calculated. The workpiece is placed in distilled water for three days until the thickness increases by 0.1 mm.
• The previous parameters are re-measured and the maximum volume of moistened wood is calculated.
• The workpiece is dried and re-weighed. The mass of the dry sample is divided by the maximum volume. The result of the calculations will be the basis density.
• The mass of the dry workpiece is measured again. Based on these values, the specific gravity of wood is calculated.

This algorithm for calculating specific gravity is prescribed in GOST 16483.1-84. The recommendations indicate that measurements are best carried out on blanks that have the shape of a rectangular lens. The edges of the sample must be well processed. The dimensions of the workpiece should be as follows: length - 20 mm, width 20 mm, height 30 mm.

How much does a cube of pine weigh - how does humidity affect it?

The same pine tree can have different weights. This is directly related to the amount of moisture in it. Depending on the percentage of water in wood, dry, air-dry, wet and wet species are distinguished.

• Pine whose humidity is from 10 to 18% is called dry and the weight of one cubic meter is 505-510 kilograms.
• If the humidity is 19-23% , then the mass of one cube is 520 kg.
• At 24-45%, the pine is considered raw and its weight will be about 550 kilograms.
• All wood whose moisture content exceeds 45% is called raw; its cubic meter weighs from 550 to 730 kilograms.
• A cube of freshly cut pine can sometimes reach up to 820 kg, since its humidity exceeds 90% .

More specific information can be found using special tables that show the correspondence between the percentage of humidity and the mass of a pine cube.

The weight of wood also directly depends on its density. Density, in turn, is directly proportional to the moisture content of the wood. Dry pine has a density of 0.50-0.52 g/cm3, and its cubic meter weighs approximately 515 kilograms .

Completely dried pine wood with a density of 0.48 g/cm3 has a weight of 480 kg, if the wood is raw, then the density is 0.64-0.85 g/cm3, 600 - 700 kg per cubic meter.

In general, the higher the moisture content of the rock, the higher its density, and, accordingly, the greater the mass of one cubic meter of wood.

Information about the exact weight of pine (pine lumber) can be useful when transporting it and choosing the carrying capacity of a vehicle.

In general, there are two types of wood weight:

1. Specific.
2. Volume.

The specific gravity is approximately 1540 kg/m3 and is defined as the mass of one cubic meter without taking into account various indicators such as the type of wood, its humidity and density.

The volumetric weight depends on the moisture content of the tree and its species. The unit of measurement for this weight is g/cm3 . It is worth noting that it is customary to calculate it only at normal humidity, namely 15% .

Determine the volumetric weight according to the following formula:

уw=y0(100+w) / (100+(Y0-Yw))

W – wood humidity;

Уw – volumetric shrinkage;

У0 – volumetric weight in a completely dried state;

уw – volumetric weight of wood.

There is another concept - conditional volumetric weight . It is defined as the ratio of the weight of a completely dry piece of wood to the weight of the same freshly cut sample. The overall humidity does not matter, so it is more convenient to use. It is calculated using the formula:

U0=y conv/(1-y)

Where Y0 is the weight of dry wood, and y is the shrinkage of the rock, shown as a percentage.

You can do all the calculations yourself, or you can turn to special online calculators that will give you the exact answer in a few seconds.

How much does a pine tree weigh? Specific gravity of firewood

A distinction is made between the specific gravity of wood (solid wood pulp without voids) and the specific gravity of wood as a physical body. The specific gravity of wood matter is above unity and depends little on the type of wood; on average it is taken equal to 1.54. The specific gravity of the wood substance is important in determining the porosity of wood. The conventional volumetric weight has the advantage over the volumetric weight that it does not depend on the amount of shrinkage and does not require recalculation to 15% humidity. This makes it possible to significantly simplify calculations and provide more uniform results when determining the γconditions of several samples.

Classification of rocks by density

The density values ​​of different types of wood differ quite significantly. Based on standard moisture content, rocks are usually divided into three groups:

- low-density species (540 kg/m3 or less): conifers - pine, spruce (all types), fir (all types), cedar (all types), common juniper; from deciduous trees - poplar (all types), linden (all types), willow (all types), black and white alder, chestnut, white, gray and Manchurian walnut, Amur velvet; – medium density species (540-740 kg/m3): conifers – larch (all types), yew; from deciduous - drooping, fluffy, black and yellow; eastern and European beech, elm, pear, summer oak, eastern, swamp, Mongolian; elm, elm, maple (all types), hazel, walnut, plane tree, rowan, persimmon, apple, common and Manchurian;

– high-density species (750 kg/m3 and above): white and sand acacia, iron acacia, Caspian honey locust, white hickory, hornbeam, chestnut-leaved and Araxinian oak, ironwood, boxwood, pistachio, hopshornbeam.

Among the foreign species, there are those whose wood has both a very low density (balsa - 120 kg/m3) and a very high density (backout - 1300 kg/m3).

The tables of the State System of Standard Reference Data (GSSSD), published by Gosstandart of Russia (“Wood. Indicators of physical and mechanical properties of small samples without defects”), provide more detailed information on the density of wood, indicating the type of tree species and the area of ​​its growth. The density of bark has been studied much less than that of wood. The available data are very varied. Comparison of these data with the average density of wood at standard humidity shows that the density of pine bark is 30-35% greater than wood, spruce - 60-65%, and birch - 15-20%.

The influence of wood structure on its properties

The density of wood is also greatly influenced by the water it contains. Firstly, it increases the mass of the sample, and secondly, the swelling of cell walls in water causes a change in the volume of the sample. Therefore, the density of wood is determined either in the absence of water or at a certain mass fraction of it in the wood. Completely dried samples actively absorb water vapor from the surrounding air and in some cases it is more convenient to handle wood samples that contain a known amount of water and are in relative equilibrium with the surrounding atmosphere. In technological calculations, the basic density of wood is sometimes used, which is the ratio of the mass of an absolutely dry wood sample to its volume in the most swollen state. This condition is typical for freshly cut wood and wood that has been in contact with water for a long time. In this case, the basic relative density is actually determined; however, by equating 1 g of displaced water to a volume of 1 cm3, they transform it from a dimensionless quantity into a quantity that has dimension.

Tree species are characterized by certain values ​​of wood density, which are influenced by growing conditions. Depending on the botanical species, the density of wood varies widely. For example, for tree species common in Russia, the density of absolutely dry wood varies from 350 kg/m3 for Siberian fir to 920 kg/m3 for iron birch.

Based on the density of wood at a humidity of 12%, all domestic species are divided into three groups: with low density (540 kg/m3 or less) - spruce, fir, pine, cedar pine, poplar, willow, linden, alder; medium density (550...740 kg/m3) - larch, birch, beech, oak, elm, maple, ash; high density (750 kg/m3 or more) - acacia, hornbeam, certain types of birch, oak, ash. It should be noted that coniferous wood, with the exception of larch and some types of pine, has low density. Closely related to this is the property of permeability to liquids and gases. The permeability of wood characterizes its ability to pass liquid or gases under pressure, which is very important for wood processing processes. The permeability of wood is due to the existence in the wood of a system of cell cavities and intercellular spaces communicating through the pores. A dry cell wall, as already noted, has low porosity, and its components are either included in crystalline regions or are in a glassy state, which makes the cell wall practically impermeable to non-polar environments. In polar liquids, cell walls swell greatly and their porosity increases. For technological purposes, water permeability and gas permeability are most important. Since there is a good correlation between these characteristics, and testing wood for gas permeability requires much less time, in practice, to assess the permeability of wood, its gas permeability is often determined.

The permeability of wood, estimated by the mass or volumetric flow rate of a liquid or gas through a unit surface area of ​​a wood sample, is maximum in the axial direction, i.e. along the fibers. It is several times higher than in conifers, since it coincides with the direction of the vessels. The permeability across the fibers is much less and is greatly influenced by the medullary rays. The formation of mature and especially heartwood reduces permeability, and in certain species the heartwood becomes waterproof.

What is the density of oak, beech and other species?

In descriptions of interior doors and the types of trees from which they are made, the term “wood density” often appears. Descriptions are good, but they don't provide as clear an understanding as numbers - what does "a little tighter" mean? Values ​​in the form of numbers give an accurate picture, on the basis of which you yourself can decide which wood is most suitable for making interior doors. Before moving on to the numbers, let’s define what wood density is and why you need to know it.

The density of wood is the ratio of its mass to volume. Simply put, the more a cubic meter of wood weighs, the denser it is. The density of wood, called , depends on humidity, so it is customary to operate with values ​​​​obtained at a humidity of 12%.

We've sorted out the first question, let's move on to the second. The density of wood directly affects two important properties - strength and hygroscopicity. Dense wood has higher strength and, in most cases, hygroscopicity. The latter term means that doors made of high-density wood are more susceptible to changes in humidity - everyone knows that wood tends to absorb moisture and expand. For this reason, doors made of aspen, linden or pine, located at the very bottom of the table, are used in saunas and baths, where beech doors would simply stop closing.

Values ​​are given in grams per cubic centimeter (g/cm3) at 12% humidity. Please note that in some cases average values ​​are given.

Brief description of wood properties: Hornbeam.

Hornbeam is most widely distributed in Europe, Asia Minor and Iran. The wood is shiny, heavy, sticky. Color: whitish-gray. Density: 750 kg/m (cube). Brinell hardness: 3.5.

Lacewood. One of the most beautiful Australian trees. The color is light brown with a characteristic grain. Density: 910-1050 kg/m (cube). Brinell hardness: 5.5. Paduc. with bright positive energy. Color: Light yellowish-red to dark brick-red, mottled with darker lines. Density: 850-950 kg/m (cube). Brinell hardness: 4.2.

Wenge. Homeland of wenge wood tropical jungle Western

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Table of weight of 1 m3 of pine depending on its humidity.

It is very difficult to determine the percentage of moisture using improvised means. And this is a very important indicator for determining such a parameter as the specific gravity of a cubic meter of pine. Typically, these procedures are carried out in special technological laboratories.

The easiest way when purchasing a material is to check the moisture content from the manufacturer. Then, using the table presented, find out the weight of a pine cube with a flag from 5% to 90% and the density of the material:

Specific gravity and density of pine depending on humidity

Density and performance characteristics

In furniture production, construction and other areas of activity where wood is used, the technical and mechanical qualities of the product are important. When choosing, pay attention to such an indicator as the density of wood, for example, Scots pine at a humidity of 12% has a density of 500-540 kg/m3. Some types of this rock have a lower density, less than 400 kg/m3. Modified, technologically advanced products have different indicators, since the properties of laminated veneer lumber differ from their solid counterpart. During the production process, the workpiece is impregnated with glue, and the fiber is compacted during pressing. The product turns out to be significantly stronger, more stable, but denser. Depending on the number and thickness of the lamellas, the timber can add up to 20% of the mass. The density increases by the same value, while the strength increases even more - 30-70%. The characteristics are decent, considering that this material shrinks much less and absorbs moisture. A wooden house built from laminated veneer lumber will be stronger, more reliable and durable than its conventional counterpart.

Table of how much a board cube weighs

• Wood species
• Density, kg/m3

Artificial and natural drying

Ideally, lumber should be dried in natural conditions, that is, in a ventilated room with a roof or in the open air under a canopy.

Since dry lumber is in greater demand than material with natural moisture, accelerated drying methods are used. The question of how safe this is for the material remains controversial. There is an opinion that artificial drying leads to too rapid evaporation of moisture, which causes a change in the geometric dimensions of the boards. Due to microscopic damage to the fibers, curvatures and unevenness are formed. In particularly advanced cases, cracks appear.

However, drying using forced air, including warm air, performed without fanaticism, is unlikely to lead to such obvious negative consequences.

The moisture content of the wood should be taken into account when organizing transportation. Let's say you bought dry boards, but during storage they were exposed to rain and did not dry completely. Their weight, naturally, will no longer be the same as upon delivery.

engages in the procurement and processing of coniferous wood - Siberian larch, cedar and Angara pine in the Krasnoyarsk Territory. We are a full-cycle wood processing company: from logging and sawing round timber to the production of lumber and supply of finished products to St. Petersburg and the Leningrad region.

The average values ​​of the specific gravity (SG) of larch, at twelve percent relative humidity, are considered to be the standard indicator, and without any connection to the grade of wood. The value in undiluted form has no practical significance, only taking into account humidity and grade. That is, the statement that a carbon fiber can have any effect on the quality indicators of a product is simply unfounded. Moreover, it is impossible to accurately calculate a stable indicator, taking into account only a cube of dry larch; this is not plastic and the humidity (and therefore the hydrocarbons) in it is constantly changing.

Specific gravity has practical application only when calculating the (again, average) mass of a specific batch of larch. It is extremely rare for an experimental carpenter to refer to this indicator in order to calculate the possibility of gluing wood of different species.

Our position on this issue is somewhat different from the established one: if the project is carried out by specialists, and cargo transportation is also not accessible to amateurs, then why stuff the customer with data about what the dry weight of larch might be, because the potential client is interested in completely different indicators.

To satisfy the direct interest in our products, we can do a lot: harvest timber in the Krasnoyarsk Territory, and process it there in our own production. After which, bring a varied assortment to St. Petersburg and sell it at prices below the city average. If you decide to buy dry larch or natural moisture from our company, then we can even deliver the timber you purchased to any point in the Leningrad region and, if necessary, provide assistance in the implementation of the wooden project.

But attempts by a curious client to independently connect the strength and specific gravity of dry larch into a single whole will only lead to mixed feelings (due to the fact that the proportions of changes in moisture content in wood are not unambiguous and depend on a wide variety of factors). In the best case, there will be a desire to thoroughly study the physical characteristics of wood in order to accurately know the specific gravity of larch natural moisture, depending on the grade of specific wood.

As in the case of hydrocarbons, the customer’s use of information about how much dry larch weighs is very rarely justified. For example, if you carry out an independent calculation of the foundation. But do not forget that larch itself will not remain exceptionally dry for very long (both outdoors and indoors). And design and estimate documentation is best prepared by highly specialized specialists. Accordingly, the dry weight of a cube of larch has no practical meaning, since the timber can be delivered and installed by us, and in the shortest possible time.

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.

The specific gravity of wood has the form of the 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 density of wood of different humidity (kg/m3)

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:

1. With low volumetric mass (less than 540 kg/m3). These include coniferous trees: pine, spruce, fir, cedar and some deciduous trees. These are all types of alder, poplar, linden, aspen, chestnut.
2. With an average specific gravity of 550–740 kg/m3: beech, elm (elm), larch, all types of maple, rowan, apple, ash.
3. With a high level of density over 750 kg/m3: birch, oak (Araksin, chestnut-leaved), hornbeam, dogwood, pistachio.

Of course, this is an incomplete list of breeds. Based on the wood density values ​​indicated in the table, you can determine whether the species belongs to the group.

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.

The average specific gravity is the main characteristic of raw materials when carrying out calculations, since the value contains an average assessment of tests of lumber 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 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. Load-bearing structures of houses and industrial facilities are made from oak. 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 rocks are more suitable for finishing work, where the load on the product is minimal. Wood with low porosity is plastic and bendable.

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. Wood species with a high mass-to-volume ratio are called solid fuels. 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.