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A "carpenter" did this to a big double joist in my house (top floor), I was under the impression that one does not cut a hole this close to the edge of a joist, especially not one this big! Should I be worried about this joist and how would I go about repairing it?

enter image description here

The cut is about 1.2 meters from the wall

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    In the states (or anywhere covered by International Building Code (IRC)), holes cannot be closer than 2" to the top or bottom of the joist. Holes also cannot be larger than one-sixth the depth of the member (2" in a 12" joist), and cannot be in the middle one-third of the span. – Tester101 Dec 7 '17 at 12:12
  • Does the fact that this hole is only 1.2 m from one wall (how far from the other wall?) reduce the weakening effect of the hole? Is there some sort of metal plate or wooden reinforcement that could restore this joist? Could this plate be applied only to the one exposed side or must reinforcement be applied to both sides? – Jim Stewart Dec 7 '17 at 12:29
  • Since the upper side of a joist is in compression, one failure mode would be buckling, and to counter buckling repair might require reinforcement on both sides. This is of course only if this hole is truly weakened to the point of requiring repair. Could a heavy steel tube be inserted and held in with glue? Assuming this is a floor joist, what would be the result of putting a heavy load on this area? – Jim Stewart Dec 7 '17 at 12:40
  • @Tester101 It just seems insane to have put it that close to the edge, especially when there was NO reason to do so. – klogd Dec 7 '17 at 13:18
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    There's no point to filling the hole. Steel plates should be long enough to reduce leverage on the joist. A wood repair is probably also fine. – isherwood Dec 7 '17 at 14:23
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I was under the impression that one does not cut a hole this close to the edge of a joist

In the UK, holes must be on the centre-line of the joist. In the US, holes may not be closer than 2" to the edge of a joist.

especially not one this big!

In the UK, hole diameters must not exceed 1/4 the height of the joist (1/3 in the US I think?). The hole in your photo looks like 1/3.

Should I be worried about this joist?

It no longer meets safety standards in the US, UK and probably many other countries.

Because the hole is so close to the top edge it is effectively a notch.

So far as I know, the depth of a notch cannot exceed 1/6th (US) or 1/8th (UK) of the height of the joist. The bottom edge of the hole in your joist looks about a third of the way down the joist.

how would I go about repairing it?

I've seen UK advice to use steel strapping across the damaged section and a foot beyond on each side. They use two-part epoxy to ensure the load is spread across the whole length of the steel reinforcement. The steel needs to be substantial since it has to cope with compressive load.

Others suggest nailing (or screwing or bolting) and gluing reinforcing timber or ply (3/4") to both sides of the damaged section. Extending at least 12" beyond the damaged area. Nails are generally better under shear loading than are screws.

I don't know what is acceptable in the US.

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Whoa...you’re going to repair this by “making a small notch in the top of the joist”???

There’s a famous line in the movie Cool Hand Luke. The guard says, “What we have here is a failure to communicate.” I think we have a failure to communicate with this damaged beam, (and it is a beam as a “double joist”.)

That extra joist is there for a reason...there’s extra load on that beam. Putting a small notch in the top of it isn’t going to help...even if you add side plates. ...and no one has mentioned how many and what size fasteners to use. (Be careful nailing or screwing from both sides of the beam...you could easily split one or both of the joists.

If I were you, I’d first call my attorney and then call a structural engineer (not a civil engineer) or an architect.

  • Making the small notch is not to repair the damage to the joists, it is to accomplish the original mission of getting the black tube into the wall. So far it seems the cost of reinforcing these with steel or timber will be about the same as what I owe my ex-carpenter for "work" he's done, so should be fine. still wastes a lot of my time though – klogd Dec 8 '17 at 12:03

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