Making Extension Support Box for Wood Stove Chimney

James

New Member
  • #1
Jay, can you send me exact measurements of the pressure treated 2x4s that you used to make the box. I have the exact setup, with a 2 ft stainless pipe to get away from wall, but have yet to cut the hole in wall. I am now wanting to cut and construct the box you mentioned, but thought I’d you had dimensions it would save me time. Thanks,
James
 

James

New Member
  • #2
Jay, can you send me exact measurements of the pressure treated 2x4s that you used to make the box. I have the exact setup, with a 2 ft stainless pipe to get away from wall, but have yet to cut the hole in wall. I am now wanting to cut and construct the box you mentioned, but thought I’d you had dimensions it would save me time. Thanks,
James
Also meant to ask you how you braces the piping against the wall....the straps that I have are meant to be only a couple inches away from the wall. Not sure how I will make the 18 foot run steady since it will be just around 2 feet away. Thanks for your suggestions!
 

JGaulard

Moderator
Staff member
  • #3
Hi James. I will do this in the morning when it's light outside. I'll take measurements and more photos and post everything here. Also, just to let you know, I have walls that were built with 2x6s, so yours will need to be built with the same thing. You'll need to adjust your own measurements for your wall thickness.
 

JGaulard

Moderator
Staff member
  • #4
Okay, here are some photos and measurements.

First, this is the extension box itself. It was constructed with pressure treated 2x4s.

wood-stove-chimney-extension-box.jpg

The distance from the exterior wall is 13".

distance-from-exterior-wall.jpg

The height of the box is 11", which is the same as the support mount, I believe.

hieght-of-box.jpg

The width of the box is 17", which is, again, the width of the support mount.

width-of-box.jpg

I attached the chimney directly to the edge of the roof. I didn't need to add that aluminum flashing and I wouldn't do that again. I would also use screws that don't rust to construct the box, like exterior decking screws.

chimney-pipe-mount.jpg

This is the (almost) entire setup. The reason I have that flashing on an angle coming from the wall is to keep the rain from splattering against the siding.

wood-stove-chimney-away-from-exterior-wall.jpg

This is the Duravent chimney roof support bracket.

duravent-chimney-roof-support-bracket.jpg

I used the support strapping that came with the through the wall chimney kit to hold the rear of the mount to the wall and then I used some additional strapping I picked up at the hardware store. I'll likely replace the longer strapping with something that doesn't rust.

duravent-chimney-mount-strapping.jpg

chimney-pipe-mount-straps.jpg

If you get lucky like I did, the chimney will sit about two inches from the roof line. If you don't, you may need to use two 30° angle pipes, but the entire reason for using the two foot extension pipe through the wall and the DIY mount box is to save the $300+ for the angle pipes.

Let me know if you have questions or need more pictures.
 
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