To begin with, it is worth accepting the fact that coniferous timber is considered lighter than lumber from hardwood tree. In addition, such options are easy to process and have a long service life. They are resistant to rotting due to large quantity resins, and therefore are often used as facing material for building facades.
Before calculating the weight of lumber, it is worth considering the basic concepts:
- Dry wood is a material whose moisture content does not exceed 18%. Such products have already passed technological testing or long time were stored in a warehouse or other dry place.
- Air-dry lumber is wood with a moisture content of 19 to 23%. It is distinguished by the fact that it has equilibrium humidity. This definition should be understood as the state of a tree when its humidity is in equilibrium with the same air parameter environment. This characteristic is achieved by long-term storage of products in natural conditions. Lumber with this level of humidity excludes the use of technological drying.
- Raw wood – has a humidity of up to 45%. This forest is still at the drying stage.
- Fresh wood - as a rule, such materials are characterized by a humidity of over 45%. These are trees that have been recently cut down or those that have been exposed to water for a long time.
It is worth understanding what to determine specific gravity forests are not so simple. At the same time, we can say which breed will be relatively lighter and which will be heavier. Thus, coniferous varieties will be guaranteed to be lighter than deciduous ones, such as oak or beech. But when transporting a significant amount of timber, all sorts of incidents can happen. As a rule, all these nuances relate to the almost unpredictable weight of raw wood due to high humidity. Therefore, this issue is worth dealing with.
Weight of 1 cube of coniferous forest in practice and according to GOST
Depending on the type of wood, 1 m3 of lumber may have different weight. Yes, for coniferous species, especially if they are raw, there is a typical weight gain due to resins. The humidity of the forest itself largely depends on the season when the felling was carried out. The conditions of tree development also play a role.
It is worth understanding that there is lumber from the top and bottom of a tree trunk. It is not difficult to guess that the first option will be somewhat easier due to the fact that they initially have high humidity.
Note! Humidity plays a major role in the characteristics of the forest. Raw and dried lumber can have different weights. Sometimes the differences can be almost double.
It is worth considering the provisions normative literature. Thus, the current GOST takes 12% as the standard humidity value. Under these conditions, light species rarely leave the 600 kg mark per cubic meter of forest. The lightest among conifers is Siberian fir. The weight of a unit volume of such a breed barely reaches 390 kg. But larch, which is also classified as medium, weighs 660 kg. Thus, it is heavier than birch, but slightly lighter than oak.
However, calculation tables cannot always give a 100% guarantee that a particular timber for a certain volume will weigh as indicated.
Results
In addition, for the convenience of calculations, you can use special programs. One of these is the forest cubiter. It will allow you to find out without tables how much a particular breed weighs, based on its basic parameters. Using the software, there is no need to search for the required positions in the table for a long time; it is possible to carry out interpolation. Everything is quite simple. Such programs show the weight of the forest in kilograms per cubic meter.
At construction work When it comes to using lumber from coniferous trees, correct calculations of the specific gravity of pine wood are very important. Unlike other various building materials, this variety does not have a single specific gravity, which somewhat complicates the selection process. The fact is that pine wood, like any wood, is natural material porous type. Accordingly, depending on the type of pine and the percentage of humidity, the specific gravity of the pine changes.
As mentioned above, the main parameters influencing volume weight pine trees, is humidity. For example, the highest specific gravity is found in still untouched, growing pine. This is due to the fact that the tree needs high humidity for growth. At the same time, humidity is both a useful substance and a carrier of other, no less useful, vitamins and minerals. The amount of moisture depends entirely on the type of pine, the harvesting season and the area. Humidity levels of “live” pine can vary from 29% to 81%. The lowest indicator, respectively, is for dried pine, since the humidity in this state tends to zero.
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:
| Pine moisture percentage | Specific gravity (kg/m3) | Density (g/cm3) |
| Standard, 10 to 12% | 500 - 505 | 0,5 - 0,505 |
| 1 - 5 % | 480 | 0,48 |
| 12 % | 505 | 0,505 |
| 15 % | 510 | 0,51 |
| 20 % | 520 | 0,52 |
| 25 % | 540 | 0,54 |
| 30 % | 550 | 0,55 |
| 40 % | 590 | 0,59 |
| 50 % | 640 | 0,64 |
| 60 % | 680 | 0,68 |
| 70 % | 720 | 0,72 |
| 78 - 90 % | 750 - 820 | 0,75 - 0,82 |
| 80 % | 760 | 0,76 |
| 100 % | 850 | 0,85 |
Practical meaning and importance.
Among coniferous building materials, wet, dried, dry and damp pine trees are valued. However, these terms do not give a specific exact value for humidity, so knowing clear numbers is essential. For example, requirements for the use of fallen pine are not provided for by legislative acts. But, when performing certain work, GOST sets humidity standards, for example:
Wood has been used in construction work since ancient times. Of course, this material is still very popular due to the presence of excellent technical characteristics. Wood itself is a natural material of a 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 of counting arises required quantity 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 | Humidity 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. The density of the material plays a special role in the weight of m3 of wood; accordingly, for the right decision Given the questions posed, it is necessary to determine the value of the density. There are two types of density:
Specific gravity (density of wood substance)
Volumetric weight (density of a structured physical body)
Wood substance is a mass of solid wood materials without natural voids. This type density is measured in laboratory conditions, as it requires additional measurements that are not feasible in normal conditions. For each wood of all types and species of trees, this value is constant and amounts to 1540 kg/m3.
The density of the wood itself is quite easy to determine under normal conditions. To do this, just weigh a piece of wood and measure its volume. Process the obtained data using standard arithmetic operations using the following formula: Y = M/O, where Y is the specific gravity of the tree, M is the mass of the wood, O is the occupied volume.
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 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.
- 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.
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 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 coniferous trees: pine, spruce, fir, cedar and some deciduous trees. 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. Based on the wood density values indicated 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: what more moisture in the product, the higher the weight indicator 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 special device– 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 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. 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.
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 beams 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, the mass of one such unit of lumber is calculated.
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 example. 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:
volumetric 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 of a certain size per 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.