| Building (with) Green |
|
|
| Written by Steve | ||||||
| Wednesday, 05 March 2008 | ||||||
Page 4 of 4 On the notches, the shape of the notches are designed to stay closed as it shrinks. Here , the notch in the log above is basically an upside down V sitting on two sloped cuts in the log below - imagine the legs of a horse rider sitting on a saddle. The notch purposely is made to sit tight against the saddle on its edges but space is left inside the notches so as the log shrinks in height it is able to slide down and the notch remains tight.  For those paying attention, you might wonder how the notch can slide down when the two logs are already tightly scribed to each other along the long groove. In fact to allow for shrinkage at the notches, the long grooves are not in fact tight to each other at first. This is because the notches are 'underscribed' by a small amount. That is the scribe setting used to create the tight long grooves is reduced down a bit when scribing the notches caused the logs to be initially 'hung up' at the notches by the same amount. The exact amount depends on which course of logs are being placed and other factors ( which is to say that it is not an exact science yet) but in general about 1/2" on the bottom course and diminishing to about 1/8" near the top. The remaining 1/8" is closed from compression - ie: the weight of the logs and the roof itself will tend to compress the wood to closure.  These techniques are still being perfected but in general it has been found that these give very satisfactory results. Certainly better than techniques used in the past as the following photo of an historic log cabin I took in the US will attest. Note that in this photo a different technique was used called chinking which intentionally leaves gaps between the logs which are then filled with lime plaster or mud - less than ideal but which has also managed to survive for significant amounts of time, though the weathertightness of these homes to today's standards may have been questionable. I hope that you can see that if you work with the wood, then even properties which we would nomally consider undesirable can be put to great benefit and a building's effectiveness may actually improve over time. |
||||||
| Last Updated ( Wednesday, 05 March 2008 ) | ||||||
| < Prev | Next > |
|---|
Quoteflash
|
"People who will not sustain trees will soon live in a world that will not sustain people." Bryce Nelson |
Functional Art of the Woods
