Drilling Joist Holes

Old 05-24-16, 04:11 PM
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Drilling Joist Holes

I've already done most of the research, but haven't found an answer if there is a limit/requirement in how close 2 joist holes can be to each other.

I am planning to relocate a washer/dryer and in doing so will be discharging the washing machine into a utility sink that pumps the water up and then across the basement to connect into existing lines.

The joists are 2 x 10 (actual 1 1/2 by 9 I think) and the holes I'm planning to drill are 1 1/2" to pass a 1" pipe for the utility sink pump. I also only need to drill through 3 joints. And I'm NOT drilling in the middle 1/3 of the span, but closer (about 5 feet) off the walls.

There is already a 1 1/2" discharge line for my dishwasher running though a few joists. And In my planning, I wanted to drill holes in one of the same joist for the utility sink pump about 3 1/2 inches next to it. Will that be an issue in drilling 2 holes close to each other? Or do I need to space and separate it further?
Old 05-24-16, 04:53 PM
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Here is a link to a nachi.org photo. It sounds like your plan is fine.
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Old 05-24-16, 04:54 PM
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3 1/2 inches is fine for spacing (IIRC, 2" is the minimum). In addition to not drilling in the middle third of the span, don't drill closer than 2" to either long edge of the joist (bottom or top).

I assume you are using flexible hose of some sort but if not, have you thought about how you will get a length of pipe into those holes? You will need to use a bunch of short pieces with couplings in every joist bay.

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