Re: cutting holes in joists
Posted by Mike on June 19, 19100 at 12:16:13:
In response to Re: cutting holes in joists
: I am looking to relocate my toilet in my 1st floor flat. In its new location, the waste pipe (around 4" diameter) will need to cross over 1 possibly 2 8x2" joists in order to reach the outside waste stack.
: Can you tell me as to whether it is safe to drill out a 4" diameter hole from a 8" thick joist leaving 2" above and below the hole? Also where on the joist span, is the best place to cut the hole?
: I have read that it is safe to cut a hole upto half the thickness of the joist whilst notches should be no greater than 1/6th of the joist depth, is this true?
: Youre advice would be greatly valued. Many thanks.

In non engineered joists you can cut away up to 60% of the member centered from top to bottom. In engineered "I" beams you can cut away material to within .75" of the top or bottom chord. In all cases you need to make the hole round and make it a clean cut without any splitting in the wood. Any sort of drill or rotary hole say are your best tools for holes in structural members.

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