The modern world standards of the residential houses heat insulation demand to follow strict insulation rules, and traditional log houses often do not meet such rules.
This happens for two reasons:
A) Joints between logs lack sufficient insulation, in particular, between longitudinal slots and in the corners.
B) Insufficient heat-insulating properties of the wood itself.
When selecting manufacturing technology for log houses, we have decided upon technology of the Swedish company Stenlund, with its key advantage – manufacturing of the longitudinal inter log connection with tongue and groove. An additional tongue is milled in the upper log along with the standard Swedish cope, and an additional groove is made in the lower log on its connector. Heat insulation performed for such complex profile minimizes possibility of wind blowing along the wall of such groove.
However, thermal insulating properties of the wood do not ensure compliance with the world standards in the residential buildings heat insulation. Longitudinal tongue-and-groove has significantly increased heat insulation of our log houses. This solution is suitable for bath-houses and country cottages, but it is not acceptable for large residential houses with higher insulation requirements. Simple calculations show that, in order to comply with the modern European standards, walls must be 450–500 mm (!) thick and made of solid impermeable wood, which is highly expensive and impossible to manufacture by using wood.
As an easy call, some choose additional heat insulation of the log house external walls from the inside with glass wool 100–150 mm thick and board facing. This may look ugly: many clients would like to see real logs in their interiors, and not some randomly faced external walls and round log internal walls. Moreover, facing of the shrinking log walls is not quite technically simple solution, which may lead to further problems.
Due to this, we have developed technical solution of the heat insulation problem – double external walls. We offer our clients to build the log houses of logs 200 mm thick and increase wall insulation not due to bigger log diameter or internal heat insulation and house facing, but due to manufacturing external wall of two parallel log walls with a distance of 150 mm between them. Space between these double walls may be filled with air, glass wool or green fiber. Final cost of such wall will correspond to the cost of a log house made of logs with diameter of 270–280 mm, but heat insulation of a wall made of two logs 200 mm thick will be two or three times higher than that of one log 280 mm thick (depending on presence of wool). Heat conductivity coefficient of glass wool is at least three times lower than that of wood. Thus, the equivalent overall thickness of heat insulation in terms of wood would be: 200 + 3х150 mm (heat insul.) + 200 mm = 850 mm (!!).
Heat insulation of the roof is increased from 200 to 300 mm in such log houses, according to the Scandinavian standards.
Thus, our new wall structure:
a) keeps external and internal authentic log design of the houses;
b) increases the log house heat insulation two or three times;
c) increases strength of the log house external walls.
Build your residential houses based on our highly heat-insulated log houses with double external walls!