Just curious what the ontario building code says about this.
Im installing a bathroom exhaust fan in a basement and need to put the 4" ducting through the rim joist (I know the hole should be centered) but in the OBC is there an allowable hole size that can be put through the exterior rim joist? I mean its ffully supoorted below by a continous plate and teh oundation.
Ive heard before that the allowable hole size is one third of the size of the joist meaning in a 2x8 rim joist I would only be able to cut out a 2 3/8" hole? Not sure if this is true or not. Anyone know?
Just call your local AHJ. The rim joist is fully supported, a fan hole is probably acceptable as long as a point load is not directly above it (then there would be solid blocking existing). May have difficulty if too close to the ground for snow load stopping back-flapper operation... may require x distance from house openings...etc.
P.S. I'll move you to HVAC.
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