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How to choose the diameter of the log for construction. The thickness of the walls in a wooden house

When starting to make a log house, special attention is paid to the thickness of the log itself. If you pick it up according to all the rules, you will be able to minimize heat loss and extend the service life of the building, without overpaying for extra cubic capacity.

Optimal dimensions of the diameter of a log for the construction of wooden buildings:

  • house for year-round use – 32-26cm;
  • summer cottage – 22-18 cm, with periodic visits in winter – 24-22 cm;
  • bath – 26-18 cm (winter or summer version);
  • gazebo and other non-residential premises – from 15 cm.

What affects the diameter of the log


The larger the diameter of the log, the higher the cost of wood. As the volume of material increases and older trees are used during construction. The older the tree, the larger the diameter of the log.

Usually the diameter of the log corresponds to a certain age of the tree:

  • from 24 to 26 cm – 40-50 years old;
  • from 26 to 28 cm – 60-80 years old;
  • from 30 to 32 cm – 80-100 years;
  • over 32 cm – over 100 years.


As you know, wood has a limited service life due to the influence of aggressive natural factors (especially moisture). The thicker the wood, the slower its destruction occurs.

Thermal conductivity

The thickness of the wall directly depends on the thermal conductivity of the material. When buying a wall building material, you need to find out its thermal conductivity coefficient. It will help you determine if the cross-section of the log meets the requirements of building codes and calculate the optimal size.

Calculation of the diameter of the log

Estimated wall thickness = coefficient of thermal conductivity multiplied by the coefficient of thermal resistance of the given structure (it should be up to 3.2 m ° C / W).

According to the handbook, the thermal conductivity coefficient of pine with a density of 500 kg / m3 in cross section is 0.18 W / m ° C.

Formula for determining the wall heat transfer resistance coefficient (R req):

Heat transfer resistance coefficient:

R req = 1 / 8.7 + 0.54 / 0.18 + 1/23 = 0.1149 + 3.00 + 0.0434 = 3.1583 m ° C / W

Wall thickness

0.18 * 3.16 = 0.568 m

0.568m is the minimum thickness of a wooden wall with a given thermal resistance.

In practice, in the climatic conditions of Belarus, round timber with a diameter of about 30 cm is used. Even without additional insulation (or with a minimum layer of insulation), heating costs are noticeably reduced.

You can overpay once for the material, or incur increased heating costs on a monthly basis. While there are no preconditions for a decrease in heating prices in Belarus, the choice is yours.

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