The weight of a cube of a log of natural moisture. How much does a cube of raw pine board weigh - How much does one dry and wet wood suitable for construction weigh

Softwood lumber is on average considered lighter than hardwood lumber. 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 - are 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 processing stage, as well as on the forest area 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 wood 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 very different from the dry mass. 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 conifers, Siberian fir 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.

Starting the construction of a house, or making repairs, sometimes you have to deal with questions that seem to be simple at first glance, but you can’t give an answer to them right away. It seems awkward to address such a question to specialists, but you need to know for sure. For those who can access the Internet, it’s easier - I typed in the search engine “How much does a cube of wood weigh” and after half a minute I got an exhaustive result. And by the way, really, how much?

Influence of humidity on wood weight

The weight of wood does not always have the same indicator. What does it depend on? First of all, from the moisture of the tree. If we compare, for example, oak and birch, it turns out that a cubic meter of oak weighs 700 kg, and birch weighs 600 kg. But it may be otherwise. 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 are there 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 at the same moisture content have different weights, as in the first example above. If the humidity is not the same, then the weight can fluctuate in one direction or another. The standard humidity is 12%.

Different density - different weight

Another factor that affects the weight of wood is its density. The highest density of iron and ebony is from 1100 to 1330 kg / m 3. Boxwood and bog oak are close to them - 950-1100. In ordinary oak, beech, acacia, pear, hornbeam, the density is about 700 kg / m 3. It is even lower in pine, alder, bamboo - 500 kg / m 3. And the lowest is cork tree, only 140 kg/m 3 .

Why do you need to know the weight of a cubic meter of wood

Having knowledge in this area is sometimes very important. By purchasing construction material, its amount is impossible for a non-specialist to determine by eye. Knowing the dimensions of the timber or lining, the material from which they are made and its moisture content, simple calculations allow us to determine the weight of the purchased goods. How much does a cube of wood weigh - in this case, the answer to this question will help you figure out whether the seller released the goods to you correctly.

Heat dissipation of wood

In addition, there is another indicator - heat transfer. She will come to the aid of those who use wood as firewood for heating. The higher the hardness, i.e. the density of the wood species, the higher its calorific value. Of course, no one will heat the room with boxwood, but choosing between linden and pine or birch and acacia, you can get much more heat if you know which of these species are the hardest. Information about the density of each tree can be gleaned from the tables, since all this information is systematized for ease of use.

Weight of dense cubic meter, kg

Breed	Humidity, %
Breed	10	15	20	25	30	40	50	60	70	80	90	100
Beech	670	680	690	710	720	780	830	890	950	1000	1060	1110
Spruce	440	450	460	470	490	520	560	600	640	670	710	750
Larch	660	670	690	700	710	770	820	880	930	990	1040	1100
Aspen	490	500	510	530	540	580	620	660	710	750	790	830
Birch:
- fluffy	630	640	650	670	680	730	790	840	890	940	1000	1050
- ribbed	680	690	700	720	730	790	850	900	960	1020	1070	1130
- Dahurian	720	730	740	760	780	840	900	960	1020	1080	1140	1190
- iron	960	980	1000	1020	1040	1120	1200	1280	—	—	—	—
Oak:
- petiolate	680	700	720	740	760	820	870	930	990	1050	1110	1160
- eastern	690	710	730	750	770	830	880	940	1000	1060	1120	1180
– Georgian	770	790	810	830	850	920	980	1050	1120	1180	1250	1310
- Araksinsky	790	810	830	850	870	940	1010	1080	1150	1210	1280	1350
Pine:
– cedar	430	440	450	460	480	410	550	580	620	660	700	730
- Siberian	430	440	450	460	480	410	550	580	620	660	700	730
- ordinary	500	510	520	540	550	590	640	680	720	760	810	850
Fir:
- Siberian	370	380	390	400	410	440	470	510	540	570	600	630
- white	390	400	410	420	430	470	500	530	570	600	630	660
- whole leaf	390	400	410	420	430	470	500	530	570	600	630	660
– white	420	430	440	450	460	500	540	570	610	640	680	710
- Caucasian	430	440	450	460	480	510	550	580	620	660	700	730
Ash:
- Manchu	640	660	680	690	710	770	820	880	930	990	1040	1100
- ordinary	670	690	710	730	740	800	860	920	980	1030	1090	1150
- sharp-fruited	790	810	830	850	870	940	1010	1080	1150	1210	1280	1350

The table shows the average weight values. The possible maximum and minimum values of the mass are respectively 1.3 and 0.7 of its average value

The Drova72 company conducted an experiment, we weighed 1 folding cube (skladometer) of birch chopped firewood, natural humidity, ~50%. The results of this experiment will be discussed in more detail below.

This experiment in no way claims to be - "scientific" or "100% objective", rather something in between information from the Internet and laboratory research. Nevertheless, this is the first step towards 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 dense cubic cube weighs ~790 kg.

In the text below, we reveal in detail the essence of the experiment. The calculation is made on the basis of information from GOST "a 3243-88 and a guide to sawmilling.

Why do we need this?

small digression

The volume of firewood in stock meters is measured by multiplying the length, width and height of the woodpile. But, the concept of "1 storage cube of firewood" is rather vague, because. firewood in the woodpile can be stacked with different stacking densities and there is no GOST or regulation that would explain what "packing density" is and how to measure it. That is, the same amount of firewood (1 conditional storage meter) can fit from ~0.7 to ~1.3 stock meters, depending on the stacking density and the 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 poles in such a woodpile is greater than in the one on the left. In this case, in both cases, the volume of firewood in the warehouse 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 the different type firewood, this image shows the density of stacking firewood in a woodpile.

specifics

Sometimes we have disagreements with our clients about the volume of firewood in the warehouse meters. We brought firewood to stacking in one volume, the client transferred the firewood to his woodpile, measured it, and his volume turned out to be less than originally declared.

In the example above, the contention is almost always due to stacking density. Therefore we decided weigh 1 stack of birch firewood, and correlate its weight (mass) with the data, which are presented in GOST 3243-88 and in the Sawmill Handbook, Moscow, Forest Industry Publishing House, 1980

By comparing the weight of our firewood storage meter with the data from the above sources, we will understand whether we stack the firewood tightly enough in the car before delivering it to the buyer.

Sequencing:

First, we will put 1 stacking cube in the woodpile.
Weigh this cube on the scales.
We will compare the resulting weight with the data from GOST 3243-88 and the Sawmill Handbook.

By different sources, the moisture content of freshly sawn birch can vary from 60 to 80%. We buy firewood birch, which is harvested (cut down) from 1 to 4 months ago from the moment when it is brought to us for further processing. The humidity of such a birch is on average 40-50%. We will do the calculation based on 50% humidity.

In the guide to sawmilling, the weight of a dense cube of ordinary birch at a moisture content of 50% is 790 kg. To convert the weight of the warehouse meter to a dense cube (or vice versa), you need to apply a coefficient. We will take it from GOST 3243-88, with a log length of up to 0.5 meters of 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 561kg.

We weigh

Conclusions and comments

First of all, we wanted to test ourselves, because. sometimes there were doubts about honesty in relation to our firewood buyers. Now the doubts have been dispelled. Our stacking density and volume of firewood in stacked cubic meters meets the necessary requirements.

If we turn again to the guide to sawmilling (Note 1), it is obvious that the weight of 1 storage cube at a moisture content of 50% will not always be 560.9 kg, because. the weight of one dense cube of 790 kg is an average value and can range from 553 kg to 1027 kg. And, therefore, 1 birch chipped firewood storage meter (taking into account the coefficient 0.71) can weigh from 392kg to 729kg. This is probably due to the different density of trees and poles.

Of course, this experiment cannot be considered 100% objective, because. At a minimum, a moisture meter is needed to determine humidity. Our forest can have different humidity levels. There are many suppliers and the terms of harvesting and delivery are different for everyone, respectively, the moisture content of the forest can vary from 30 to 60%.

If you have any suggestions or comments on this material- please write to our email: [email protected] website.

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 to 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.

Table of some reference values for the density of wood and the weight of firewood during loading

wood species	Specific gravity g/cm3	Specific weight kg/m3	Loading weight of firewood kg/m3
Ash, beech	0,68	650 - 750	480
Birch	0,65	620 - 650	450
Oak	0,71	650 - 800	470
Larch	0,66	580 - 635	420
Pine	0,52	480 - 520	360
Spruce	0,45	420 - 450	330
Acacia	0,69	650 - 750	460
Elm	0,65	620 - 660	440
Aspen	0,48	460 - 550	350

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 also used less frequently due to high resin content.
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, specific gravity 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.

Before carrying out any construction or repair, always calculate the required amount of material. For example: brick, rolled metal or lumber: unedged, edged board or wagons. Usually the seller provides wood delivery services, but it happens that this is not possible. And this question already has to be decided by the buyer himself: what kind of car needs to be ordered in order to bring required amount scaffolding for the construction site?

lumber features

Even if the number of trees in cubic meters, then according to the carrying capacity, the choice of the machine will still need to be calculated. Even knowing how much a dry board cube weighs, the mass of a cubic meter of material on the market can vary significantly. And the fault for this will be not only the type of tree, for example: it is a pine or spruce, birch or cedar, but also the place of the log house, the humidity of the surrounding air, and even the time that has passed since the day of the log house. The weight of a unit cubic meter of the same tree will also differ from the degree of processing of the material. The mass of round timber, under the same conditions, will always be less than the mass of unedged timber. This is due to the fact that the packing density of the material in one cube will be different. The round timber cannot be stacked tightly on top of each other, large voids will remain. The same applies to unedged boards. The surface will not be pressed tightly from the sides.

Therefore, when calculating the carrying capacity of transport, you need to focus on transportation, possibly maximum weight cargo. So 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 during its felling, and hence the maximum humidity and density.

Indicators affecting the weight of lumber

The moisture content of wood is a very important indicator that you need to pay attention to. With its high degree, the tree swells, and at a low degree, on the contrary, it dries out. Everything construction works it is recommended to perform with already dried lumber, in which the moisture content does not exceed 15-20%. Otherwise installed damp forest, over time, drying up, will change its geometric dimensions (decrease) and thereby violate the integrity of the building.

Dried wood becomes more durable, lends itself well to finishing, is not subject to mold and insects, and retains its building qualities for a long time. Before drying, the remaining bark is removed. This is necessary for uniform drying and avoiding damage by insects (bark beetles).

Drying of the forest is carried out by specialists on outdoors. The wood is stacked in a pile, on the spacers between the rows, so that the air can pass freely and dry the boards from all sides. It is advisable to locate the drying place in a place where direct sunlight does not fall on the material, but there is good ventilation. Top row stacks must be pressed with a load to prevent deformation.

Weight calculation

Now let's calculate the weight of the most common lumber that can be encountered on the market.

We calculate the mass using a calculator, according to the formula M \u003d V * ρ, kg, where:

V is the volume of material required for calculation, m3. In our case given value is 1 m3;
ρ is the density of wood, kg/m3. For freshly cut pine, the value is 820 kg/m3.

Substituting into the formula, we get:

M=1*820=820 kg.

Similarly, knowing the density of the material, you can calculate how much a cube of a larch board weighs:

M=1*940=940 kg.

And this means: no matter what size the edged board:

150x150x6000;
25x100x6000;
25x150x6000;
50x150x6000.

Their weight in one cube will be approximately equal, the main thing is that the composition of the wood, as well as the moisture index, remain unchanged, only the number of boards will differ.

The question arises, how much does a cube of a dry board of the same pine weigh? This state of wood is accepted when its moisture content is up to 20%. 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 vehicle increases by 30 or 50 tons!

Therefore, when choosing lumber, it is important to know the moisture content of the board. In order not to make a mistake in the choice of transport or the number of flights required to transport the entire forest.