Log houses have a long history in North European countries and probably they were the first type of wooden house ever made. Thanks to modern technologies, today's log houses are very different from what they used to be and log buildings can be found in any size, ranging from very small cabins to huge villas/residences. Also, shape of logs is no longer rough and roundish but also oval or square logs are available making a each log house a unique product.
We have to agree that machined glue laminated timber square logs are really a beautiful construction material, capable of giving a very unique contemporary look while mantaining a traditional feeling.
From an engineering point of view those logs have very good properties as they can have wide spans, allowing for construction of very large internals spaces without need for much additional supports (posts, columns).
So, if today's logs have so nice qualities,
All that glitters is not Gold
Despite the solid feel of a machined log and its undeniably appealing look, there are areas where logs really do not offer much.
Here we give you three reasons why you should not build a log house:
Here we give you three reasons why you should not build a log house:
1) Energy performanceThe U-value of a 300mm thick wall made of compact wood cannot be better than 0.40 W/m2K. For the same thickness, Qhaus double framed external walls reach an U-Value of 0.15 W/m2K... which makes them 2.6 times more Energy Efficient of a log wall of the same size.
Of course log house producers know the downside of their product and a few solutions have been developed in the attempt to solve the problem of Energy performance.The most efficient solution comes in the form of machined glue laminated insulated logs. These logs contain insertes of insulation material which contributes to reduce the overal U-value of the log wall. Needless to say this solution is much more expensive than a standard machined log.
On top of the cost increase, introducing a "soft" material inside the log requires in general an increase of the overall thickness of the wall and, even in cases where smaller thickness can be used (one floor houses) the amount of insulation that can be packed into the wall is still way smaller than what you can pack into the same wall if it was made with timber frame... so, however you look at it, the thermal performance of a log wall is (and will always be) lower than the performance of a timber framed wall of the same thickness.
As a matter of fact log housing is finding its bottleneck in the most recent versions of building codes. As those become more and more strict in terms of energy performance, in many Countries today is simply not allowed to build residential houses with pure log technology (i.e. in Norway, Finland, Estonia and other Countries U-value limits are lower than 0.25W/m2K).
2) Air thightnessA log house is basically a large 3D puzzle when all the pices come in form of "bars". A timber frame element house is also a 3d puzzle but its pieces come in a much larger format.
As result, in a log house there are many more connections between its parts. if you measure the "lenght" of those connections in linear meters you come up to an interesting comparison.
As result, in a log house there are many more connections between its parts. if you measure the "lenght" of those connections in linear meters you come up to an interesting comparison.
For a sample square house of 100m2 (10x10m) you would have about 400m of connections in the log house version and just about 80m in the timber frame element version!
With a ratio 1:5 it is easy to understand that it is 5 times more likely to have air leaks in a log house than in an element one. Why air thightness is so important in a modern low-energy house is discussed in a previous article.
With a ratio 1:5 it is easy to understand that it is 5 times more likely to have air leaks in a log house than in an element one. Why air thightness is so important in a modern low-energy house is discussed in a previous article.
Again, as building codes become more and more strict, in some Countries it is not recommandable to build your house with log technolody as it would be a risk ensuring the required air tightness.
3) CostIt should be clear by now that, unless you live in warm climates where building regulations are still permissive, building a log house would pose quite a few challenges.
This means that if you go for it you have to take extra care to construction details. It might be necessary for example to foresee extra insulation inside the house and to use special products to ensure the complete sealing of all connections.
This means that if you go for it you have to take extra care to construction details. It might be necessary for example to foresee extra insulation inside the house and to use special products to ensure the complete sealing of all connections.
All this translates into extra costs that add up to the already expensive nature of glue laminated machined logs.
Wheather this cost is worth is up to you to decide but you must be aware that timber frame elements houses come generally at a better price point.
Wheather this cost is worth is up to you to decide but you must be aware that timber frame elements houses come generally at a better price point.
No comments:
Post a Comment