Log houses are the warmest and most environmentally friendly. Wooden walls perfectly retain and accumulate heat and regulate the level of humidity. On every corner we hear that a wooden wall only 240 mm thick has the same thermal conductivity as a brick wall 1 m thick. Impressive, right? But there are situations when they built or bought a new log house, lived in it, and with the onset of the first serious cold weather, they realized that the house was cool and there were drafts. Then we seriously think about the insulation of the building, even to the detriment of beauty. But there may be more banal situations: they bought an old wooden house, which is already rather "worn out" and requires serious measures for warming. So a serious question arises, how to insulate a log house, what materials can be used, and what absolutely cannot be done.
Why is it cold in a log house - a little theory
What are the most common problems faced by log house owners who complain that it is cold in winter? Firstly, these are drafts in the rooms. Secondly, it blows on the legs. Thirdly, the house cools down quickly if the heating is turned off. Fourth, the walls are too cold. And many related nuances, from which it is concluded that the house must be urgently insulated, and it is imperative to start from the floor, since it is the coldest. Let's see what happens in the room when it is heated.
Imagine that we have a log house that we heat with some kind of heat source. What we have involved in heat transfer: heat source, air, ceiling, walls and floor. How does this happen? Recall the school physics course. Heating up from the heat source, the air rushes up - to the ceiling. Resting against the surface of the ceiling, it spreads over it, giving off heat and cooling. As a result, we get the ceiling - the warmest surface in the room. Further, the air flow reaches the walls and descends along them. Since our walls are much colder than the ceiling, the air cools much faster, and its speed increases. Now the air has already reached the floor, having fairly accelerated, and rushes along it at such a speed that an illusion of such a strong cold draft is created, as if there is no floor, and you are standing right on the snow.
If you place a heat source near the inner walls, as is usually done by heating with a fireplace or a portable radiator, then the heat transfer rate increases significantly. There is a constant draft in the room, it turns out that we ourselves are to blame for the fact that it is cold in the house.
No wonder there are norms that heating radiators should be located under the windows. The outer walls are initially the coldest, in contrast to the inner ones, which are quite inert. If you place a heat source near the outer wall, then the air will rise up, then fall back onto the walls, but now not at such a speed and will not cool so quickly. After all, the inner walls are quite warm, so passing them, the air will not cool too much. And descending along the outer walls, it will rest against the heat source again, where it will heat up and rise up. As a result: the room warms up faster, the structures retain heat better, since it is accumulated rather than wasted.
What you need to check to eliminate unnecessary heat loss:
- Ceiling. The very first outpost to check for leaks, as up to 70% of heat can escape through it. Be sure to insulate the attic or attic floor to retain heat inside the room.
- Walls. The second outpost is the outer walls and everything that is in them: windows, doors, etc. Incorrectly installed windows and doors are the scourge of log houses. Through them, the lion's share of heat can go away, without even having time to heat the room. Immediately from the radiator and into the gap under / above the window. Plus, do not forget to check whether the walls are carefully caulked, maybe cracks have already formed somewhere.
- Floor. The last thing that can be a source of cold is the floor. It should be checked for serviceability and insulated in a standard way. Also for the winter it is worth reducing the ventilation of the underground, blocking most of the air.
I would also like to note that in order to make the heating of a log house better, it is possible to equip the house with “warm floors”, in addition to the existing heating system. Then warm air will be distributed more evenly throughout the room, due to which drafts near the floor will disappear and the house will cool more slowly.
By the way, too thin walls can also cause cold in the house. For example, for a climate with a cold harsh winter, but low humidity, walls 200 - 240 mm thick are sufficient. But for regions with wet winters, even if the temperature does not fall below -20 ° C, it is advisable to use logs with a diameter of at least 400 mm, and preferably 480 mm. Such regions, for example, include Moscow and the Moscow region, St. Petersburg and the Leningrad region. Be sure to take this into account when developing a log house project so that it does not hurt excruciatingly later.
What materials can be used to insulate a log house
The standard procedure for insulating a log house includes insulating the ceiling or attic, caulking the walls and insulating window and door frames, and insulating the floor. If everything is done correctly, then no additional measures will be needed.
Taking into account the fact that log houses are built in order to create a dwelling from natural environmentally friendly materials, it would be foolish to use polystyrene for insulation. Then all meaning is lost.
For attic insulation log house can be used sawdust, ecowool(cellulose cotton), seaweed, straw. In extreme cases, you can insulate mineral wool.
Caulker walls produced only with natural materials: moss, tow, hemp, jute, flax-based tape heaters And jute. The main requirement for the material is that it must have properties similar to wood.
For wooden floor insulation on logs you can use natural backfill materials, and you can mineral wool in rolls. And here concrete floor will require a denser material, suitable polystyrene foam, extruded polystyrene foam, cork And basalt wool in slabs with a density of more than 160 kg/m3.
If, after all the standard procedures, the house is cold, maybe because the thickness of the logs was chosen incorrectly, maybe the house is already very old, or maybe the heating was calculated incorrectly, and you decided that without such a procedure as warming the walls of a log house , you can not do, then you should know some of the nuances.
The material that can be used to insulate log walls should have the following properties:
- To be vapor-permeable on a par with wood or to a greater extent if it is laid outside the building.
- Be moisture resistant so as not to accumulate moisture, which can lead to rotting of the tree.
- Be fireproof and resistant to the appearance of pathogenic fungi.
- It is easy to pass air.
- Have a sufficiently loose structure to fit snugly against a rounded log wall and leave no gaps.
Considering all of the above, to insulate a log house from the outside, you can use:
- Ecowool.
- Mineral wool (although it is not natural, it is easy to install and publicly available).
- Sawdust or sawdust-granules (filling material).
- Expanded clay (filling material).
Wood is an unusual building material. It not only “breathes”, but is also a kind of air recuperator. And if someone will assure you that the vapor permeability of wood across the fibers is slightly greater than that of reinforced concrete, know that you can object. Entering the thickness of the wood across the fibers, then the air is distributed along the fibers and exits through the end. In other words, the tree "breathes" with its ends.
It is precisely because the wooden walls are “living” that the following materials cannot be used:
- Styrofoam.
- Extruded polystyrene foam.
- Polyurethane foam.
- Mounting foam for sealing gaps.
- Sealants.
Using vapor barrier materials will cause the wood to rot, or if you protect it from the inside with a vapor barrier, you will turn a wooden house into a thermos. In this case, the whole point of building a house from a log will be lost. But the choice is still yours.
How to insulate a log house from the outside
As we have already found out, it is necessary to insulate the walls of a log house only when all other measures for insulation have not brought the desired result.
If you are interested in the question of how to properly insulate a log house from the outside or from the inside, then here is a definite answer for you - outside. This is due to the properties of the tree to breathe, accumulate moisture and give it away. In the case of an external location of the insulation, air and moisture will freely exit the tree and ventilate.
You can start warming only a year and a half after the completion of the construction, when the log house sits down.
Log wall caulk
Even if you have already made the final decision to insulate the house, the first step is to carefully caulk it. We examine all the walls for visible cracks. Then, in calm weather, we pass through the house with a candle, holding it close to the walls. If the flame leans towards the wall, then there is a gap in this place from which it blows in winter.
One of the most effective ways to look for cracks in logs is in winter when the house is heated, you need to go around and inspect all the walls. If you notice frost, it is sometimes also called a “bunny”, which means that heat is leaking from the room in this place.
Caulking should be done in dry, warm weather, using tow, jute, hemp or roll insulation. We put the material in the gap between the crowns and push it with a special tool - a caulk.
Ventilated facade device
Insulation of a log house from the outside is carried out by installing a ventilated facade. This design allows the wooden wall to "breathe" and release moisture.
First, we treat the walls with an antiseptic and flame retardant to protect the tree from fire and mold. On top of the walls we fill the crate, which will hold the insulation. To do this, we use a bar with a section of 50 mm. We fill vertically with a step equal to the width of the insulation boards minus 2 - 3 cm.
As a heater, we will use mineral wool in slabs with a density of 35 - 50 kg / m3, 50 mm thick.
Important! When installing insulation on a log wall, we encounter some inconvenience. The fact is that the wall is uneven, laying the insulation close without gaps is almost impossible. Therefore, we put insulation into the gaps (openings) between the wall and the battens of the crate. To do this, you can use "Basaltin" in rolls or interventional insulation - jute, lnovatin.
We insert mineral wool slabs between the crate, pushing them tightly into the opening. We do this from the bottom up.
On top of the insulation we mount a windproof waterproofing superdiffusion membrane. It must have a vapor permeability equal to at least 1400 g/m2 per day or higher.
Important! Properly selected wind protection for a ventilated log wall facade is almost the most important thing in insulation. This membrane will not allow moisture and wind to pass through from the outside into the thickness of the insulation and walls, but at the same time it will release moisture and air from the inside to the outside, thus giving the walls the opportunity to “breathe”.
On top of the windshield we stuff a crate of 50 mm bars. We mount siding on the crate. It can be a vinyl siding that imitates wood, or you can use a block house, then the wall will have the same log profile as the real one.
For the entire thickness of the crate (50 mm), a ventilation gap is formed between the membrane and the facade. Air vents must be provided at the bottom and at the top so that air can circulate freely.
How to insulate a log house from the inside
The option of insulating the house inside must be considered before performing a ventilated facade. Perhaps standard insulation measures will be enough, and you won’t have to spoil the appearance of the walls.
The following procedures can be attributed to the insulation of a log house from the inside: insulation of the floor, ceiling, roof and walls. Moreover, experts are categorically against installing insulation inside the walls, since in this case the tree will dampen and rot.
Ceiling and roof insulation
The first thing, as soon as they found that it was cold in the house, we insulated the ceiling and roof.
If the house is one-story with an attic, then we lay a waterproofing film on the attic floor, pour insulation on top with a layer of 150 to 250 mm. It can be ecowool, sawdust, seaweed or ordinary mineral or glass wool in rolls. It is not necessary to cover the heater. From above, you can lay boards for ease of movement around the attic, but you do not need to equip the floor.
If the house has an attic floor instead of an attic, then it is necessary to insulate both the ceiling between the floors and the roof slope. It is enough to lay 50 - 100 mm of insulation (any) in the ceiling. If the attic floor is wooden, then we fill up the insulation between the lags. If the floor is concrete, then we use basalt wool in slabs or, in extreme cases, foam. To insulate the roof slope, we lay a waterproofing film directly under the roof, then lay the insulation (mineral wool) with a layer of 150 - 200 mm. We lay a vapor-tight membrane on top of the insulation so that the material is not saturated with moisture from the room. We mount the crate and trim for the attic.
The above procedures should be enough to make the house warmer.
Insulation of the walls of a log house
Let's go to the walls. Since it is impossible to mount insulation inside log walls, what we can do is to caulk well from the inside, insulate all window and door openings.
To insulate openings, we use rolled interventional insulation or, in extreme cases, mineral wool, but in no case do we blow out the cracks with mounting foam, it will quickly become unusable, since the walls of a log house are constantly in motion, and foam is a non-plastic material.
To finish the walls of a log house from the inside, you can upholster them with wooden clapboard. In this case, the insulation between the wall and the finish cannot be mounted. The house will become a little warmer due to the fact that the wall will have a slightly greater thickness, as well as air gaps from the side of the heated room between the flat lining and the curved surface of the log walls.
Insulation of the floor of a log house
In order for the floor in a wooden house to be warm, it must be equipped, observing the entire technology of laying the floor on the ground. Be sure to perform backfilling, waterproofing and insulation. If the floor is wooden, we lay insulation between the lags with a layer of 100 - 150 mm. Top rough and finish floor.
If the floor is concrete, then between the layer of "lean" concrete and the main layer we lay polystyrene foam or extruded polystyrene foam in slabs with a thickness of 50 - 80 mm.
Before insulating a log house with a ventilated facade, equip the house with a “warm floor” system. Perhaps this will be more than enough to ensure a comfortable stay in it. Then you don’t have to sew up beautiful log walls, because such houses are being built because of their primitive beauty. What's the use of covering the walls with siding?
Insulation of a log house is a whole range of measures. If everything is done correctly, start from the ceiling and roof, then caulk the walls well, insulate the windows and doors, the floor, there will be no need to sheathe the house from the outside. If this does not help, there is another way to keep warm in a log house, which is not described here - to build a glazed veranda on the coldest side of the house, thereby expanding the area and forming an air barrier.