Keeping checking in check...

Started by NM_Shooter, January 15, 2008, 11:00:28 AM

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NM_Shooter

I just saw Don's sliced log science fair project, and it reminded me of something that I thought I would share and ask for input.

My house has several vigas (large peeled logs) supporting the living room ceiling.  When these were put in, I noticed that one of the old fart framers was ripping a slot as deep as his circ. saw would let him on the top of the viga.   I asked him what he was doing, and he said that this would encourage the log to check on the top where it would not be seen, and to minimize the checking in other places. 

Over the 10 years I've lived here, the logs have checked some more, but not as much as other homes I've seen.  I have a guest room with 6X8 beams supporting a ceiling.  I bought the beams a bit green from a mill up near Raton NM.  When I installed them I did the same and ripped a slot on top of them.  Those beams are 3 years old now and look very, very clean.  When I did it, I wondered if I was compromising the strength of the beam.  I suspect that if so, the compromise is very, very little. 

If I remember right, the old fart said that the Japanese called this "breaking the back" or something similar.  Has anyone else heard of this?

-f-
"Officium Vacuus Auctorita"

MountainDon

Interesting! I wouldn't think you could even measure any change in stiffness.  :-\

Ya' can always learn something from an old fart... more from some than others.  :)
Just because something has been done and has not failed, doesn't mean it is good design.


desimulacra

I have never used it but have researched Scandinavian scribe log homes. My information is second hand but I was impressed with the site I'm quoting, the builder had researched log homes and backed his claims up.  The builder had an arched interior doorway made from large (10-14") logs. He had scribed them in place with a notch cut in the top of each log, almost to the end. Each and ever log had split on the top as predicted (he had pictures). I think he stated that as the log dries the moisture has to escape somehow creating this checking problem and will almost always take the path of least resistance (the top groove) to check. He also stated that the checking was natural and had little effect on the strength of the log. I'm at work so don't have that web site here.

Mark
West Tennessee