huangyhg

log beam notching
i have a log home project in the southwestern style where the log roof beams are spaced approx. 3'-6" o.c. structural deck spans over them. the logs are simple span. in several instances, for reasons the builder was exceptionally vague on, the top of the log was notched at the bearing end. there is no notching in the tension zones. in the worst case the notch extends 1/2" past the face of the supporting 2x wall. in the majority of cases the notch is contained within the wall depth. the notches vary from 1/2" to 1/3 the dia. of the log. any coments, tips and suggestions?
wrong logs delivered to the site? too expensive to haul away and replace? just guewwing, but does the contractor have a bond? what about local inspections? i wouldn't put in a beam that lost 1/3 of its depth at the ends.
if i understand your question, i believe you've already answered it yourself. a notch in a beam is a concern only on the tension side. the reason being, of course, that you could end up with the log splitting along the grain at the corner of the notch. as long as the beam does not cantilever past the wall, it won't see tension on it's top side. since bending is worst at mid-span, and shear only becomes a concern code-wise at a distance away from the support equivalent to the depth of the beam, i'm sure that you've got adequate strength even with the reduced cross-sectional area.
in my experience with timber frames and log homes, beams are often oversized.
hope this helps, if not, maybe restate your question.
cheers,
mike
if your spans are fairly long, shear at the support should not be a problem so some notching the logs over the support may not be critical on simple spans. losing 1/2 of the log depth is probably a little excessive and should be looked at. i engineer a lot of log homes and it isn't uncommon for builders to get a little carried away notching at the wall supports.
it is most common to knotch the bottom of the log rather than the top at the support. if you have the log rafters sticking over your gable ends to support the roof rake overhang, the top becomes the tension side of the beam at the roof support. in between your supports the bottom of the log is the tension side but that moment goes to zero at the support leaving you the just the moment from the overhang at the rake. any engineer looking at your structure would need to know the building dimensions, roof loads, overhangs, type of wood, grading of logs if done, log diameters, etc. i would recommend you get a local engineer with log home experience to look at the structure. it is cheap insurance. contact some local log home dealers or suppliers to get the name of the engineer they use.
thanks for the posts. validates what i was thinking. i guess i made it a little too confusing, tho. the depth of the notches varies from 1/2 inch to 1/3 the depth of the log. it was the irregularity of the notches that baffled me, none in the same wall line being alike, and the builder unble to tell why or for what purpose they were notched in the first place. and the notching occurred on site. the architect swears the logs arrived whole and undamaged. maybe there's some beavers nearby. good woodworkers, those beavers. when they chew on a log they leave nice square notches.

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