Drilling Thru Joists

3/14/2021 at 6:46:47 PM

Never notch a floor joist or beam. These are structural parts of a home. No 2 holes. The drain pipe could not be put through the holes anyway as it's not flexible. And absolutely no 4 hole!!! Run these items normally near a wall if possible and build a bulkhead to hold them. You can even add pot lights into the bulkhead for aesthetics. You can drill the 3/4 holes so long it is above centre of the joist.

3/15/2021 at 8:56:44 AM

I would avoid going through any load bearing joists! Not worth it if anything happens in the long run!

3/16/2021 at 12:25:10 PM

This is an excellent test question if you were looking to hire a general, carpenter, electrician, plumber or HVAC contractor because they all should at least come close to getting the correct answer without looking it up - the rule hasn't been altered forever (pre 1980 Code which is my oldest one). It's a good thing the newest Code is a free download to anyone - at least the 2019 NBC - Alberta edition.

Section 9.23.5.1. 'Notching and Drilling' reads: 'Holes drilled in roof, floor or ceiling framing members shall be not larger than 1/4 the depth of the member & shall be located not less than 50 mm from the edges, unless the depth of the member is increased by the size of the hole.'

The next sentence reads: 'Floor, roof and ceiling framing members are permitted to be notched provided the notch is located on the top of the member within 1/2 the joist depth from the edge of bearing & is not deeper than 1/3 the joist depth, unless the depth of the member is increased by the size of the notch.'

Of course both rules apply to dimension lumber framing; the Code also contains span tables so you can see if your joists and beams are deeper than the min. required. If you are thinking of a vertical notch in the beam for the water lines it is possible if the beam is over-designed. If you have a home from the '60s (like I do) you might find you have 2 x 8" floor joists which are already over-spanned so compromising these might not be a good idea.

For engineered lumber (I joists) you're not permitted to notch the top or bottom cords without an engineered 'repair' detail; product vendors can supply you with a framers guide handout which describes where holes are permitted (also searchable online).

The Code doesn't talk about proximity of one hole to another nor does it talk about holes drilled in rim joists, which I assume is your last question.

Common sense would suggest that it's OK to put a hole in a rim joist provided there's no enormous point-load above, in which case there should be added blocking. HVAC intakes, dryer vents, etc. are almost always run through the rim joist (commonly 6-8" dia.)

3/16/2021 at 7:12:50 PM

Short answer ... NO! It is a structural issue that compromises the floor and entire surface area above.

3/17/2021 at 8:34:16 PM

the info by "Ian" is correct. There are codes for min. holes as per size of joist and where in joist you can put them typically never more than 1"..Notching "NEVER". For the really difficult jobs I have had to typically factor in a bulkhead in floor ceiling underneath and install new plumbing. This of course will add to cost of the project but can be aesthetic with proper planning. The dryer vent through the rim joist is allowed as the bulk of load is actually on the surrounding joist but should be in a joist pocket to exterior outlet do not cross through adjoining joist to get there, again in the ceiling of area if not able you may have to build bulkheads.

3/17/2021 at 9:44:38 PM

Thanks for the badly needed support John. It's hard to be the only respondent out of 4 to say it's OK. Try to find a house that doesn't have any holes drilled in the joists for gas, plumbing. HVAC or electrical; perhaps in a perfect world on some distant planet.

I can't remember whether I learned these rules in my 1st or 2nd day on the job it was SO long ago. I would think that this subject would be covered by any trade school in the opening session.

In reality it would be extremely rare to find a situation where you would want to notch a joist or beam in the very limited location where it is permitted by Code.