Help - Joists have notches in them


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Old 07-23-07, 07:24 AM
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Help - Joists have notches in them

I discovered that the previous owner of my house notched a bunch of the attic joists (about 1/2 inch) when he nailed down plywood on top. My attic is not trussed and the electrical wires were laid on top of the joists over the insulation. He notched the joists to give a little room for the wires. I know that joists are never supposed to be notched as that weakens them. Presumably, he did this so he wouldn't have to disconnect the wires and route them thru holes in the joists. There's not much play available in the wires and they run in diagonals which presumably passed inspection some 20 years ago. I would have nailed furring strips on top to get the cavity for the wire, but this idiot either didn't think of that or was too cheap.

My question is what should I do now to fix this? I can pull up the plywood. Would nailing a metal wrap u-shaped thing over the notches strengthen them? How bad is this? Thanks for the help.
 
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Old 07-23-07, 03:32 PM
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The plywood does add some strength to the notched out areas, but I would not be happy with that. If glued/screwed to the joists, that would be better. But what he did violates NEC. Wires have to be a min. of 1 1/4" deep or protected by safety plates, neither of which you describe.
 
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Old 07-23-07, 07:53 PM
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Structurally, I don't think a 1/2" deep notch is much to worry about. Yes, the notches might weaken the ceiling joists a little and it should not have been done that way according to electrical code, but you have not even told us how big the ceiling joists are. Are they 2x4's? 2x6's? 2x8's? That's likely the deciding factor. Where the notches are in the span of the joist is important. How far they span, whether they are supported by load bearing walls, etc. Just because there are some notches doesn't necessarily spell disaster.

Attic space is not designed to be used as permanent storage space in the first place, so don't expect a CEILING to be as strong as a FLOOR. The joists aren't sized the same as floor joists and that's the reason why.
 
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Old 07-24-07, 04:39 AM
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Thanks for the reply. The joists are 2x6. The joists are 12 ft. long. They do not go over a load bearing wall for the most part. There's a double 2x10 to span open spots and carry a portion of the load bearing and they are connected to that. Some notches are in the center, at least 2 ft. from the ends but some are quite close to the end of the joist. Some joists have 2-3 notches in them spaced a couple of feet apart.

I don't use the attic for storage, but I think the previous owner did. All I have up there is a whole house fan and the TV antenna. I discovered this when I pulled up a couple of the plywood panels to install the fan.
 
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Old 07-24-07, 04:59 AM
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Structurally, a 1/2" deep notch on a 2x6 is nothing to worry about. 1/2" is 1/10th the depth of the joist, and regardless of where it is located on the joist, I highly doubt it will cause any problems if you don't overload the floor beyond it's designed capability. Notches should never be in the middle 1/3 of a floor joist but on a 2x6, I don't think 1/2" is anything to worry about. If the notches are toward the ends of the joist, that is best. Top notches are best positioned 1/3 of the way from the end, so in your case, within 4' from the bearing location.

As far as the electrical goes, you better just hope that none of the wires were hit with a nail, as Justbill was alluding to. That is the concern when the wires are not deep enough. But if the guy was careful, probably no harm was done. The problem running wires like that poses is that later owners or workers could possibly overlook the fact that the wires are even there and accidentally hit them. So really, if the plywood was completely removed, and the wires were once again exposed, it would solve that possibility and problem.

The following illustration may give you an idea of what is proper:

http://www.rd.com/images/tfhimport/2000/JA00_How_A_House_Works/20000701_How_A_House_Works_page002img001_size2.jpg
 
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Old 07-24-07, 10:14 AM
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Thanks so much. I feel better about it now. I think I will pull up the plywood and since the notches are there, put nailing plates over the wires just to be safe. He should have at least done that and he didn't.

I hope he didn't put a nail thru a wire but I guess I'll have to look carefully when I pull the plywood. If he did, do I replace that wire or could I turn the breaker off, pull the nail and mend it with electricians tape?
 
 

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