Kerfing green timbers ?

[Jimbob]

If you take a green boxed heart timber (I'm thinking of a 6"x8" SYP) and make a kerf cut in the bottom (making a chainsaw cut the length of the timber, cutting from the bottom to the center), how much will this help prevent checking and is there a downside, such as weakening the timber ?


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[Don P]

Kerfing is one of the provisions in the upcoming log building codes, so it is recognized. It does relieve stress that causes checking. If the kerf is in the plane of the load, and if the grain runout is within reason it wouldn't weaken the timber IMO. I believe the rule of thumb is more than 1/6 but less than 1/3 deep, all you gotta do is start the rip, it'll take care of the rest of what it needs. I'll try to look it up unless someone else has better thoughts. One way to look at it that kind of ties to another recent question. You can make a built up beam, this is no different if the grade is the same. If you cut all the way through and could see the inside faces you'd be in a whole different set of grading rules and the allowable strength numbers could jump tremendously. I wonder if the wood knows the difference  :D.

[beenthere]

The kerf on top would possibly be better, if the top is in compression. Less strength reduction than if the kerf side is in tension. Just a thought.  ....and depends on a lot of other things, like spiral grain, side loads, and grain structure.