Where can I find exterior chase framing details?

[Captainmikev]

Hi everyone. New to the forum and seeking your divine guidance, O Great Ones.

I have a Buderus oil-fired boiler that currently direct vents out of the back side of my house. It literally is a sheet metal vent flush with the outside wall. It leaves soot all over the siding and I can smell the stinking exhaust fumes inside the house at times.

I'm building a stainless steel all-fuel Hart and Cooley (5" or 6" diameter) chimney up the side of the house (about 24' of pipe to meet code specs) and want to enclose it with a 2-by wood framed chase (covered in vinyl siding to match the house). I can't find any details for framing a wood chase on the net. I understand that framing guidelines similar to general home construction are used, but I'd love to see a diagram, plans, pictures or even a good description. Where might I find such information?

Thanks and Arggggg !!

Cap'n Mike

 

[beekeeper]

Cap'n,

Can't help you much, but I shared your frustration a few months ago when I was trying to do the same thing on a new house. I designed a chase, but later ended up running mine inside the house for other reasons. Never could find anything worthwhile on the web. What I did find is that if you go this route you'll probably want to simply build it out of 2x4 construction and insulate the exterior walls (bringing the chimney inside the "envelope" of the house). You'll also want to sheetrock the interior walls of the chase before you install the chimney pipe. Oh, and if I was correct when I designed my chase - I think you need to install a simple floor and/firestop level with each floor/ceiling of your house, just as you would need to do if you were running the chimney up inside the house.

Hope someone else can give you more authoritative advice, but that's my understanding at least.

 

[04074]

This ain't much but... http://www.fornobravo.com/PDF/duratech.pdf

 

[Captainmikev]

BeeKeeper,

Thanks for the reply. I'm not sure I read anything about sheetrock inside the chase, though.

To make it clear what I envision, here's the plan I have developed to date:

1) the chase would be a 16" wood framed "box" (say, using 2x 4's as you suggested)
2) cut a 16" vertical "path" in the vinyl siding from the exhaust point up to the soffit, exposing the wood sheathing.
3) continue the "path" by cutting out the soffit/roof which transgresses the horizontal 16" x 16" “box” footprint.
4) install the metal chimney.
5) construct the "box" around the pipe (up the wall and thru the soffit to it's top) attaching it to the exposed wall sheathing and the framing studs underneath.
6) covering “box” with exterior plywood and Tyvec.
7) lastly, apply the vinyl siding, J channels, construct roof cricket, flashing, etc.

Thanks,

Cap'n

 

[beekeeper]

You're building this from the outside of the house, so you would not have access to the chase from the inside, I guess - so I think that makes sense. Mine was going on a new house so I could have accessed the chase from the interior before the drywall was installed. I imagine everything you're describing is fine - where some might disagree is as to whether you should go ahead and remove the sheathing and insulation that would be between the house and the chase. Doing this and then insulating around the chase then keeps your chimney warm, and is supposed to make a big difference in its drafting - there are quite a few articles on the web about this part. No idea though from personal experience. Good luck!