Volumetric weight of natural moisture pine. How much does a cubic meter of board weigh

When designing different kind wooden structures often used and such an indicator as the weight of those lumber from which they are supposed to be made. It would seem that such information can be obtained from specialized directories. However, in such literature, unfortunately, only the weight of 1 m 3 of a bar or, for example, a board is often indicated. They often buy lumber cubic meters, but simply by the piece.

The length of the timber sold by woodworking workshops can be different. But most often, such enterprises sell lumber of 6 m to the public. So what, for example, can be the weight of a beam natural humidity 150x150x6000 mm? To find out, you will have to do some simple independent calculations.

What determines the weight of lumber

It is clear that the more moisture is contained in the timber, the heavier it will be. However, the weight of such lumber depends not only on this factor. When performing calculations, in this case, it is imperative to take into account the characteristics of the wood species itself. Indeed, for example, oak timber in any case will be heavier than birch lumber.

What is natural moisture

So how do you calculate the weight wooden beam natural humidity 150x150x6000 mm of a particular breed? To make such calculations is actually not too difficult. However, before proceeding with the calculations, it is still worth deciding on the concept of "natural humidity".

In construction and in the manufacture of various kinds of products, only wood with a moisture content of not more than 12-15% is used. And even such boards and timber, in most cases, are additionally dried for some time before use.

The moisture content of only sawn wood will, of course, be very high. In any case, 12-15% of its rate will exceed significantly. It is this humidity that is commonly called natural. That is, we ultimately need to find out the weight of a wooden bursa of standard length with a section of 15x15 cm, made from freshly sawn wood.

We take into account the breed

The basis for performing such an operation should be taken from the table of lumber weights in cubic meters.

Perform the calculations in this case as follows:

find out the number of bars of a given length and section in 1 m 3;

through simple division calculate the mass of one such unit of lumber.

In one cubic meter of timber, having dimensions of 150x150x6000 mm, thus, 1: 0.15: 0.15: 0.15: 6 = 7.4 pieces will be contained. To find out the weight of the beam, in this case you need:

see the weight of a cubic meter for this particular type of wood;

divide this parameter by the number of bars in a cubic meter.

For example, at a moisture content 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 bar 150x150x6000 mm from larch of the same moisture content will be equal to 90.5 kg. For aspen, this figure will be 67.6 kg.

Instructions for calculating the weight of natural moisture timber 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 bar of natural moisture 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 get such information from special tables. So, for example, the natural moisture content of pine is 60-100%, larch - 50-70%, birch - 70-90%. These parameters should be taken in this case to calculate the weight. In this case, for obvious reasons, it will be impossible to make exact calculations.

So, how much does a beam weigh 150x150x6000 mm of natural moisture? Based on the data in the table above:

pine beams of such dimensions will weigh from 580/7.4=78.3 (60%) to 730/7.4=98.6 (100%) kg;

the weight of a bar of natural moisture 150x150x6000 mm from larch will vary from 820 / 7.4 = 110.8 kg to 930 / 7.4 = 125.7 kg.

In a similar way, it is possible to calculate beams of such dimensions of natural moisture for any other rock.

Specific gravity

There are only two types of wood density:

volumetric weight (density of the physical body wood);

specific directly wood fibers).

Above, we considered a method for determining exactly the volumetric weight of a beam 150x150x6000. Natural humidity or given 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, for beams, you can also calculate the specific density index.

You can do this using the table above. Calculations in this case will be carried out without taking into account humidity. That is, to calculate, you need to find the number of beams of a certain size in a cubic meter and simply divide the indicator from the table by the resulting number.

Thus, for pine 520 / 7.4 = 70.3 kg is specific gravity timber 150x150x6000. Natural humidity - permissible operational or any other - in this case is not taken into account in any way.

Softwood lumber is, on average, considered lighter than lumber hardwood. They are distinguished by ease of processing and durability - resistance to decay, and therefore are often used for carved facade decoration. In addition, it is from coniferous species that the longest sawn timber (more than 6 meters) is produced. Not surprisingly, they are traditionally in high demand.

The weight of lumber depends on the type of wood and humidity.

However, determining their weight is not such a simple matter. Although the main conifers- pine and spruce - obviously lighter than oak or beech, in fact, if the task is to transport a significant amount of lumber to road transport, you can expect a catch. "Fresh" wood can often have an unpredictable weight: lumber, depending on the stage of processing, as well as on the area of ​​\u200b\u200bthe forest where the trees were grown, can vary greatly in properties. Here you need to understand specifically.

The weight of softwood lumber according to GOST and in practice

First of all, humidity plays a decisive role in the properties of wood. raw wood and dried can vary in density by half. This is especially true for conifers.

Raw forest - spruce or pine - resin gives additional mass. Humidity depends on the cutting season, on growing conditions, on the part of the trunk from which lumber is made.

In particular, with regard to pine, a tree harvested after the middle of winter (January) will be 10-20% lighter than an autumn one. If a forest plot is located in an area with high standing groundwater(closer than 1.5 m to the surface), the tree will be “overloaded” with water, especially the lower part of the trunk. On the other hand, the "sucked" forest - the one from which the resin was previously collected - will be more than 1.5 times lighter than the untouched one. Needless to say, the weight of 1 m3 of freshly cut wood will also depend heavily on the humidity of the climate and similar circumstances.

In processed form, lumber is more or less equal in weight, but still, those made from the lower part of the trunk are more likely to be heavier: they are initially more moist and retain more water with the same drying. In addition, according to statistics, the beam turns out to be lighter than boards equal to it in cubic capacity (especially unedged ones), even made from the same log: the core of the trunk from which the beam is cut is naturally looser, boards are made not only from the core.

In a word, the mass of raw softwood lumber differs greatly from the mass of dry lumber. On average, the weight of one cubic meter of dry pine is 470 kg, and that of raw pine is 890 kg: the difference is almost 2 times. The weight of 1 m3 of dry spruce is 420 kg, and the weight of 1 m3 of raw spruce is 790 kg.

According to GOST, the standard moisture content for wood is 12%. Under such conditions, spruce has a density of 450 kg / m3, pine - 520 kg / m3, they belong to light species. Among conifer fir Siberian is even lighter: 390 kg/m3. Nevertheless, there are also heavier species of conifers: larch belongs to the medium-density varieties of wood, the weight of 1 m3 is 660 kg, it surpasses birch and is almost as good as oak.

The weight of lumber has an impact on transportation and storage. When erecting timber structures, weight is also important in determining the loads transferred to the load-bearing members or foundation. However, when selling lumber, it is measured in cubic meters, which causes difficulties.

What affects the weight of lumber?

Consider the factors affecting weight wooden materials given volume:

wood species. This factor determines the density of the material, since wood of the same species is characterized by similar density values. This indicator already directly affects the weight - the denser the material, the heavier. On average, deciduous trees are denser than conifers, so a cube of oak board is heavier than a cubic meter of pine board.

So, in front of you is a board cube - how much does this or that breed weigh? The weight of wood per cubic meter of lumber is given in the table (kg).

Humidity. Wood is characterized by the ability to accumulate moisture. There are two options here: the board is poorly dried, and retained its natural moisture, or was stored in improper conditions. The higher the moisture content of lumber, the heavier it will be. Therefore, even the same breeds weigh differently. This, by the way, is a way to determine the materials stored in bad conditions or slightly dried.

The use of such components in construction is fraught with negative consequences, of which strong shrinkage is not the worst.

It is also unreasonable to use such a board in construction.

Internal defects. Similar to the previous point, internal defects in wood lead to a decrease in density and weight loss.

Artificial and natural drying

Ideally, lumber should dry naturally, i.e. in a ventilated room with a roof or on outdoors under a canopy.

Since dry lumber is more in demand than natural moisture material, accelerated drying methods are used. The question of how safe this is for the material remains debatable. It is believed 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, curvature and irregularities are formed. In especially advanced cases, cracks appear.

However, drying with the use of forced air, including warm air performed without fanaticism is unlikely to lead to such obvious negative consequences.

Wood moisture should be taken into account when arranging transportation. Let's say you bought dry boards, but during storage they were exposed to rain and did not completely dry out. Their weight, of course, will no longer be the same as when delivered.

Go to alternative sources energy makes us pay attention to wood. It was it that our ancestors used to heat their homes and cook food. Furnaces, fireplaces, solid fuel boilers- for all these devices you need a tree, namely firewood. But all plants are different, and trees, having a different structure and chemical composition, differ in such characteristics as calorific value, weight, density, humidity.

How much does firewood weigh?

How to determine weight of 1 cube of firewood? Does it matter what kind of firewood you buy, fresh cut or dried? Knowing the specific gravity, moisture content and other features of wood will help to deal with this.

More than 200 species of trees and shrubs grow on the territory of our country. They all burn differently, some faster, others slower, some give off a lot of heat, and some less. When choosing a tree for a firebox, it is better to focus on a middle-aged tree, do not take too young or too old. They burn for the longest time and give off the most heat.

Also, the amount of heat given off directly depends on the density and dryness of the firewood. Wood with a moisture level of 15 - 20% is considered the most suitable for sending into the furnace, and in a freshly sawn tree, moisture is not less than 50%. Part of the heat will be spent on the evaporation of water, so the efficiency of wet firewood is much lower. Yes and dry wood weight much lower than wet ones.

The weight of wood depends on:

• structure of wood cells, their moisture content,
• wood density,
• parts of the plant (the heaviest parts are branches, the lightest are the base of the trunk),
• salt and resin content.

The weight of firewood can be determined empirically, that is, simply weigh a small piece of wood of a certain volume and, by simple calculations, find out its density (the ratio of mass in kilograms to volume in m3). But such a procedure is not convenient in all cases.

Tables of average wood weights will help make calculations easier. Conditional values ​​are given for the material moisture content of 15 - 20%. Interestingly, changing the moisture content of a tree does not change its density, although it greatly affects the value of the specific gravity.

What is the best firewood for fireboxes?

Oak firewood is considered the most optimal in terms of calorific value, followed by birch, aspen and pine.

• Oak contains few resins, but releases a lot carbon monoxide. The tart aroma of burning oak logs tones the body.
• Birch firewood burns for a long time, evenly, but has a lot of resinous substances and deposits soot in the chimney.
• Conifers are also used less frequently due to high content resins.
• It is not recommended to use poplar firewood, as it emits an unpleasant bitter odor and provides little heat.

It is best to use hardwood firewood, the specific gravity of which is high. It is desirable that the firewood be dry, not freshly cut. Recall that when buying wet firewood, you pay more for the weight, but you get less heat.

1. Tree species groups
2. Humidity dependence
3. Impact on wood quality

The density of wood is one of the main characteristics of a cubic meter of material, which is taken into account when calculating structures, choosing raw materials for production various products. The term refers to the ratio of the mass of the material to the measured volume.

What can be the density of the forest

At different breeds trees have approximately the same composition, therefore, in dry form, the absolute specific gravity for all will be conditionally the same. Its average value is 1.54 (dimensionless value). But in the table of wood density for different species, their numbers are given. 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, to eliminate air voids. In practice, as it turned out, it is difficult to fix the parameter, and it is unsuitable for calculations.

To determine the density of lumber, the calculation of its specific gravity is more suitable..

It is affected by:

• humidity;
• rock porosity.

The specific gravity of wood has the form of an average value of density calculations in its different states. Sources may vary slightly. The difference is due to a change in the level of moisture inside the trunk. To avoid confusion, we present a table with the average values ​​of the specific gravity for each individual moisture level of different types of wood in ascending order.

Table of wood density of different moisture content (kg / m 3)

Tree species groups

Typically, the tabular value of the density of timber and other lumber is measured at a moisture content of 12%. Depending on the value obtained, tree species are divided into 3 groups:

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

Of course, this is an incomplete list of breeds. According to the indicated wood density values ​​in the table, it is possible to determine whether the species belongs to the group.

Humidity dependence

All lumber contains water. Its quantity mainly determines the density of the timber and other raw materials: the more moisture in the product, the higher the weight in the measured volume.

The specific gravity of wood in the table is given in average values, since the amount of moisture in one volume is constantly changing - this is a relative value.

The changes are due to:

• external weather conditions (rain, fog, snow);
• anthropogenic factor (wetting due to human activity).

Thus, a completely dry board practically does not exist. 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 the raw material when making calculations, since the value includes an average assessment of the 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. The load-bearing structures of houses and industrial facilities. Wood with a high specific gravity is rigid, practically does not bend.
• Cedar and birch timber is characterized by low volumetric weight, therefore they are not used to create load-bearing elements skeleton structures. These breeds are more suitable for finishing works, where the load on the products is minimal. Wood with low porosity is plastic, lends itself to bending.

Dependence of density and thermal conductivity

This indicator is important for choosing a tree when harvesting firewood. The dependence is direct: the higher the density index, the more fuel in the chocks, the longer they will burn. tree species with a high mass-to-volume ratio are called solid fuel. They burn for a long time, give a good heat, but due to the dense structure it is difficult to prick. The advantage of firewood and fuel from light wood species is their flexibility in sawing and chopping, but they have a relatively small energy reserve. Logs will burn for a much shorter amount of time.