Patching a Rafter

Old 03-15-08, 12:07 PM
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Patching a Rafter

I'm slowly, but surely redoing my roof and because this will be the only time that I ever have the roof decking exposed on this 50 year-old house (I'll be selling the place sometime during the next couple of years), I'm repairing a lot of other things and doing other stuff, as I go.

With that said, today's "problem" is where I'm taking out an old (metal) chimney for a wood stove/freestanding fireplace. It's a pretty big stovepipe-like chimney and when the previous owners installed it, they obviously cut one of the rafters which left a gap.

I realize that because my chimney isn't actually attached to the rafter, when I pull out the chimney, it'll have no bearing on structural integrity, but because I'm in there, I'd like to "fix" the problem before I patch that part of the roof.

I've yet to go to the building supply store today, so I haven't asked my local dudes, but I thought that I'd throw it out to the forum: On the building supply websites, I'm seeing "nailing plates", "strap ties" and other products. What would anyone here like to suggest? Should I just "sister" a board over the 3' gap, or would you just leave well-enough alone because obviously those rafters aren't holding anything up? Though once I remove the chimney, then people would be able to walk over the spot.

Thanks in Advance
Old 03-15-08, 12:51 PM
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I'm just guessing that you have decent uncut rafters on either side of the one that has been cut. That being the case, all you would need to do is head off the cut joist to the rafters on either side. So if your rafters are 16" OC, you'd cut two 30 1/2" pieces of framing that are the same size as the rafters, and nail them between your uncut rafters, (perpendicular to the cut rafter, heading off the ends of it)... one where the rafter is cut on top, and one where the rafter is cut below the old chimney- put the ends of the cut rafter at each end in joist hangers, and also each end of the 30 1/2" pieces would be in joist hangers- this will transfer the cut rafter's load to the adjacent rafters. You're basically creating a box around where the chimney was, using 6 hangers- 4 of them at the corners of the box, and 2 on the cut rafter where it runs into this box. If you then wanted to put a piece in between where the rafter was cut out, to fill in the gap in the middle of this "box", it could just be toenailed into place since it is such a short piece and it is no longer structural.

Sistering a short piece between the cut joist, or onto the sides of the joist wouldn't really meet any codes, unless the sistered rafter was full length and spanned the entire length of the rafter- from the point at which it bears on the wall, to the point at which it meets the ridge or hip, or what have you.

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