Insulation of a wooden house

Recommendation points

• Is it worth insulating wooden houses at all?
• How to insulate a tree outside
• Insulation inside the wall

This article describes how to insulate a wooden house. You will learn which insulation is better and which one should not be used for wooden walls. The article contains a table with prices for wadded insulation, as well as alternative options for thermal insulation of wooden houses.

Is it worth insulating wooden houses at all?

With an eye to age-old log cabins, many specialists, especially employees of distributors of ready-made log cabins, insist that the tree does not need insulation.

To understand why materials are destroyed, it is enough to know the mechanics of the process of natural erosion of solids. It is based on a simple physical phenomenon – condensation forms at the point of conditional contact of temperatures. That is, moisture sprayed in the air accumulates on hard surfaces. This place is called the “dew point”.

In terms of the formation of destructive condensation, wood is no different from other solid materials – it is also destructive for it, as well as for porous stone or basalt insulation. In wooden elements it works like this:

1. The house is heated from the inside and the walls are heated to a certain depth.
2. Outside, frost affects the walls.
3. As a result, the wall can neither completely freeze through, nor completely warm up – the dew point appears inside the wall.
4. Since wood is a porous material, moisture accumulates in the pores.
5. The dew point is mobile – it reacts sensitively to the slightest temperature changes. When it gets warmer outside, the wall heats up completely and moisture evaporates from it. After 1–2 seasons, stains are visible on the tree – this is the moisture that dissolved the substances of the tree, came out (dried out). This can be achieved by warming up the wall in cold weather, but warming up wooden walls is an expensive undertaking..

At the same time, the problem with warm walls will be solved by moving the dew point outside the structural wall thickness. And here there is only one option – insulation. In other words, the walls of the house should be insulated not in order to establish a barrier from the outside cold, but in order to keep the house warm, which will evaporate moisture from the wall (shift the dew point outward).

How to insulate a tree outside

The specificity of wood as a building material lies precisely in its moisture absorption. It accumulates and releases moisture very readily. This property is mixed with its derivative – hygroscopicity, the ability to transfer moisture along the fibers from the butt to the top. Moisture in the air (steam) is not yet condensation, so it should be removed in this state. In order for the process of removing potential condensate to take place quickly, the insulation must have a higher vapor permeability than the wall material.

Comparative indicators of different heaters in mg / (m h Pa):

1. Minvata – 0.3-0.6.
2. Ecowool – 0.32.
3. PVC foam – 0.23.
4. Polyurethane foam, expanded polystyrene – 0.05.
5. Extruded polystyrene foam – 0.015.

At the same time, the vapor permeability of the tree along the fibers is 0.32 and across the fibers is 0.06 mg / (m · h · Pa). This immediately cuts off the last three types of heaters based on petroleum products – they will retain steam, which the tree will try to evaporate. There remain two types of technical wool, which will remove moisture faster than the tree itself, which means that it will work effectively with external insulation.

The undoubted disadvantage of wadded heaters is that they are so porous that they themselves need protection. Uncoated soft insulation instantly gets wet, which means its irreparable damage. Therefore, the mineral wool slabs are covered with a vapor-permeable putty on the outside..

Table. Prices for mineral wool, basalt and glass wool insulation

Brand	Size, mm	Packing price, cu e.	Package volume, m3	Price 1 m3, at. e.
“TechnoNicol ROCKLIGHT”	1×0.6×0.05	12.3	0.43	28.5
“TechnoNicol 40”	4×1.2×0.05	13	0.48	27
ROCKWOOL LIGHT BATTS	1×0.6×0.1	9,7	0.3	32.5
Isover KT-40-TWIN50	8×1.25×0.05	17	0.5	34
ISOROC ISOLIGHT-L	1×0.6×0.05	5.8	0.24	24.5
URSA P-20- U 24	1.25×0.6×0.05	32.8	0.9	36.5
URSA Glasswool M11	7×1.22×0.1	thirty	0.84	35,7
URSA GeoM-11 F (foil)	90×1.2×0.1	47.5	1.08	44
Hitrock P-75	1×0.6×0.05	6.5	0.27	24
Isover Classic-Twin-50	6.15×1.2×0.05	10.5	0.37	28.5
IZOBEL PL-75	1×0.6×0.05	4.9	0.24	20.5
“PHOENIX Glass-12”	14×1.2×0.05	22.5	0.84	26.8
“ISOLIGHT-L 150”	1×0.6×0.15	6	0.27	22.5
“Knauf Thermo Roll-037”	12.3×1.22×0.05	29.5	0.75	39.3
IZOVOL CT-50	1×0.6×0.05	7.8	0.3	26

There is also a technology for insulating wooden walls from the outside by spraying ecowool. In this case, it is necessary to arrange a frame for the subsequent packing of the membrane and type-setting protective finish – as a rule, these are siding, lining, plastic, blockhouse.

It is absolutely unacceptable to cover or embed any structure of foam or expanded polystyrene into wooden walls. These materials block the steam in the wall and cause permanent condensation inside them. As a result, even the most stubborn lumber starts to rot..

Insulation inside the wall

This method is primarily applicable to frame houses. A wall assembled from a frame and sheathed with OSB or plywood has sufficient structural strength and at the same time a large volume (80%) of the interior space. In other words, it is hollow. It is reasonable to fill these cavities with insulation, which is also soundproof. All types of mineral wool and ecowool are perfect for this purpose..

Insulation can be laid at the stage of material selection. There are two types of insulated wooden walls.

Sandwich panels or SIP panels.Such a panel consists of expanded polystyrene, limited by two OSB boards. All three layers are glued to each other. Such a panel is very effective – its thermal conductivity is very low, but at the same time it does not allow steam to pass through at all. That is, in houses made of SIP panels, forced ventilation should be provided, otherwise the inner plate may get wet.

Double bar.Green building novelty. It consists of two boards, set at an equal distance parallel to each other. Together they form a hollow beam with a cross section of 150–300 mm. They are securely fastened, and ecowool is placed inside the resulting cavity. This method is very reliable and effective, but it also has a minus – the outer beam will inevitably wear out and lose its appearance and properties. However, it should be noted that this happens much more slowly than in houses made of solid or glued beams, since the wall works (removes condensate) much better due to the looser insulation.

Thermal insulation of wooden structures usually entails the application of a protective layer. In other words, by insulating the walls, you not only block heat loss, but also protect the wall material from atmospheric erosion (weathering, burnout), significantly extending the life of the whole house.