New s.s. metal chimney and cutting roof rafter?

I am installing a new wood stove (EPA Cert.), have mechanical permit, etc.

And I have built my hearth pad (proper R-Value to code, etc.) and have located my wood stove on the hearth pad to manufacturer's specs. (Proper distance from walls, etc.) This is the *only* place the wood stove can go. The chimney is stainless steel 6" inside diameter and 8" outside diameter. I'm Using Selkirk - Metalbestos chimney parts.

So guess what? The metal chimney going straight up will go right smack dab through a rafter (45 deg. roof slope - one of many 2 x 4's at 45 deg. angle supporting roof.)

So I will need to cut the rafter....

Questions....

Can I cut the rafter, then add 2x 4's which transfer the support for that rafter to neighboring rafters?

I read that there needs to be a 2 inch separation between wood and the metal chimney. If I do this where the chimney pops up through the roof, there will be a 2" air gap going from the attic to the vented roof jack (flashing). I am concerned about insects getting into the vent, then making a home in the attic. Can I place screen or something somewhere in this area (to keep insects out)?

Reply to
Bill
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There's not a lot of extra strength in a 2x4, I would not want to add additional loads to the flanking rafters without reinforcing them.

Buy an adjustable elbow or two, and run the chimney so it avoids the rafters altogether. It's a much easier and better way to do it.

R
Reply to
RicodJour

Get some more opinions, but I would think transfering the load shouldn't be a big deal as long as the spacing on your rafters is small enough. If so, I'd probably think about reinforcing the neighboring rafters with, say, a 6' length of 2x4, then making the chimney box right in the middle of the reinforced area using 2x4s to connect the three rafters together.

Reply to
kevin

Installed a Propane Selkirk unit last year and didn't have any problems with to much heat transferring to the outside 8" pipe since fresh air returns through the gap. Any chance of venting out the wall? Otherwise I'd try and use an elbow to change the angle. If that's not an option transfer the load but you'll need to support them. Also Selkirk has a piece of steel plate that is designed specifically for going through walls and creating the 2" space without allowing bugs back through, it's also a perfect 8" hole.

Reply to
HotRod

The traditional way to do this would be to double the rafter on each side of the one to be cut, install a header between these rafters to carry the cut rafter. You should support the load until all the connections are made, though the roof will probably carry it long enough to accomplish.

If the rafters are 2x4, it must be a fairly old structure. What worries me is that they may be trusses. DO NOT CUT A TRUSS. Get further input and advice.

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Reply to
DanG

There are ways of boxing around the stack, but it may be easier and cheaper to buy a couple of 45 degree elbows and zig around hte 2 x 4.

Reply to
Edwin Pawlowski

I did just that, got further advice. I took pictures of everything and took them to my building inspector...

I told him I had the option of cutting the rafter if I wanted my chimney to go straight up from the wood stove, or using a 15 deg. or 30 deg. pair of elbows up in the attic (max bend recommended by the chimney manufacturer) to re-direct the chimney to come out between the rafters. I asked what to do?

He said *DO NOT* cut the rafter!

Then he came up with a third idea. He said he preferred a pair of 15 deg. elbows (not 30 deg.) and to place these elbows at the wood stove, not higher up, or in the attic. He said it was better to place elbows lower down rather than higher up.

This will save me money as the pipe coming out of the stove is single wall and elbows at this location will be much less expensive than using Selkirk s.s. insulated chimney elbows in the attic.

He also looked pleased that I was asking for advice in *advance* rather than going ahead and doing the wrong thing, then having to fix my mistakes after inspection.

So thanks for the advice to "get more advice"! This will be a lot less work, less worry, and less cost. Can't beat that!

Reply to
Bill

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