Shrinking Of Wooden Houses

A wooden house will shrink. No matter how dry the wood was initially, over time, during a period of approximately two years, all residual humidity will slowly evaporate from the wood and the wood will become more dry. Wood shrinks in one direction only: lateral, but not longitudinal, or in other words, logs will become thinner, but not shorter.

wood shrinking

How Much Will A Wooden House Shrink?

It all depends on the amount of humidity that was still in the wood at the moment of assembly. In Central and East Europe wooden house are often build with “natural humidity wood”, this is wood that has gone through a minimal drying period of a few months and still contains a lot of humidity. These houses can shrink up to 5%, and a ten meter house would shrink fifty centimeters down to nine and a half meters.

In West Europe this kind of wood is hardly used at all, here we use dried massive wood, or even laminated dried wood. But even massive dried wood still has some residual humidity and it will shrink: approximately 2%. A ten meter house will be 9 meters 80 centimeters meters after two years, then the shrinking has stopped. Namas/Lithouse usually work with laminated dried wood and then the shrinking is even less, approximately 1%.

wood shrinking

 

What are the consequences of this shrinkage for the construction of the house?

We leave an open space on top of every door and window frame. This way the log wall can settle and sink around the doorframe without actually pushing it down from the top.

Also door and window frames are not mounted directly onto the log wall because with all the shrinking the frame would be torn apart. Instead we mount the doorframe on a vertical lath that slides inside an inset in the log wall. The log wall can now shrink, but the vertical lath and the doorframe stay solidly in place.

While a log wall shrinks and comes down slightly, any vertical pillars keep their original lengths (only lateral shrinking). See the picture of the porch.

log house shrinking

 

The external wall will shrink, but the pillars will keep their lengths. How we solve this problem? Simple: bolts under the pillars. building a wooden houseWhen the log wall shrinks, we turn the bolts and lower the pillars. After about two years the log walls, pillars and bolts all will come to their final height, and this will make the porch a lot nicer optically.