Reframe rafters or use elbows - what's the consensus?

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timfromohio

Minister of Fire
Aug 20, 2007
644
Preparing to install Napolean 1150, but unfortunately I have a truss directly above where I'd like the stove pipe/chimney pipe to travel. The attic area directly above the stove is not very high, on the order of 2 feet. I have thought of (1) using a couple of elbows to create the necessary offset to bypass the truss or (2) trying to frame in an opening which would necessitate cutting the truss (this would be done with a close friend who is an extremely competent builder and knows what he's doing).

I figure lots of people have faced similar problems - what do you recommend?

Thanks for opinions!
 
I reframed a truss that was in the way of my install. Worked out fine in my case. I wanted a nice straight shot from my stove collar to the ceiling. Plus the less bends you have in your pipework, the better your draft will be.
 
I suppose I would reframe as well. It is more work upfront, but the stove will work better and you will thank yourself every time you clean the flue and can run the brush straight down. Plus, if you can get your friend to work for some beer, it will probably be cheaper than the elbows.
 
Tfin said:
I reframed a truss that was in the way of my install. Worked out fine in my case. I wanted a nice straight shot from my stove collar to the ceiling. Plus the less bends you have in your pipework, the better your draft will be.
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same here and chepier to go stright!
 
sawdustburners said:
cozy heat said:
I suppose I would reframe as well. It is more work upfront, but the stove will work better and you will thank yourself every time you clean the flue and can run the brush straight down. Plus, if you can get your friend to work for some beer, it will probably be cheaper than the elbows.
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drinking beer requires elbows!
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Or a long straw!
 
I'm now thinking I may just run the pipe out the back wall, since the stove is against an exterior wall, and not deal with the attic/roof/trusses at all. I've know that it's better to go straight up, but the difference in pipe length that would be outside as opposed to in the attic is ~42". Can 42" of pipe outside plus a couple of elbows make the stove draft bad enough to justify cutting trusses?
 
Its your house/install, but I'm sure everyone here would agree if you have the option of running a chimney up through the house vs along the outside wall, its always best to go up through the house.

I'm certainly not saying one method is "right" or "wrong" though. Just what traditionally works "better".
 
I have a pair of 45's creating an offset to align the pipe with the interior flue that was setup for the F400. The stack draws great, even in 50 deg weather. It's no big deal unless the height of the flue is already marginal. If I had to do it over again, I'd still do it this way rather than going to an exterior flue.
 
I have back-to-back 45's in both my stovepipes...one to avoid a rafter beam in a cathedral ceiling/roof structure (the Lopi), the other to push the stove back closer to my wall shield while aligning the pipe to the previously installed ceiling adapter box (the CFM). Both perform wonderfully and look just fine. Rick
 
If I had a higher ceiling I don't think I would question using elbows to create an offset, but we have 8 foot ceilings and are worried that it might look strange having the stove pipe angle out into the room (the stove is on a hearth constructed against an exterior wall).
 
My workshop ceiling's 10'. The stove sits atop a 12" high hearth. 32" above the stovetop, the back-to-back 45's are installed, bringing the stovepipe farther out into the room, then straight up to the chimney adapter. I know it's hard to see clearly in this photo. The reason the top 32" of stovepipe seem to get "fatter" is that I have a heat shield installed on the single wall pipe, because the chimney adapter was actually installed 3" closer to the back wall than it should have been. Anyway, perhaps this'll give you some idea of what it might look like in your installation to do something similar. Rick
 

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If thats your workshop I'm soooo jealous!
Rusty
 
Then reframe the truss. If it's done competently by a pro that knows what he's doing it should be fine. You will be happier with a straight-up install.
 
There is no way to cut or modify a truss. If you do you need an engineer to re-design the whole thing.

Sorry, but any competent builder should know this.

Especially if you plan on cutting through the bottom chord. You essentially remove the stability of the truss and comprimise that section of the roof system.

I don't mean to be a party pooper. But I would just use some offsets or try and reposition the stove if possible.

Now, you may cut the truss and nothing will happen for years. The choice is yours.

J.P.
 
SmokinJoe said:
There is no way to cut or modify a truss. If you do you need an engineer to re-design the whole thing.

Sorry, but any competent builder should know this.

Especially if you plan on cutting through the bottom chord. You essentially remove the stability of the truss and comprimise that section of the roof system.

I don't mean to be a party pooper. But I would just use some offsets or try and reposition the stove if possible.

Now, you may cut the truss and nothing will happen for years. The choice is yours.

J.P.
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Just build a header,its done by competent builder everday without an engineer. Sorry but it pretty eazy but i think he is just going through the wall
 
SmokinJoe said:
There is no way to cut or modify a truss. If you do you need an engineer to re-design the whole thing.

Sorry, but any competent builder should know this.

Especially if you plan on cutting through the bottom chord. You essentially remove the stability of the truss and comprimise that section of the roof system.

I don't mean to be a party pooper. But I would just use some offsets or try and reposition the stove if possible.

Now, you may cut the truss and nothing will happen for years. The choice is yours.

J.P.
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Smokin Joe is right. Some parts of a newer home come with a type of warranty, most new roofs do, and your trusses should too. If you cut an engineered truss, you may (or probably will) void any warranty that may be in place. Every certification class for installers will tell you NEVER cut an engineered truss. It is your house tho, but be careful. I install (and sweep) offsets in houses with 8' ceilings on almost a weekly basis and they look fine, draft fine, and are no big deal to sweep. Also much less expensive than going thru the wall and up
 
coreystaf said:
SmokinJoe said:
There is no way to cut or modify a truss. If you do you need an engineer to re-design the whole thing.

Sorry, but any competent builder should know this.

Especially if you plan on cutting through the bottom chord. You essentially remove the stability of the truss and comprimise that section of the roof system.

I don't mean to be a party pooper. But I would just use some offsets or try and reposition the stove if possible.

Now, you may cut the truss and nothing will happen for years. The choice is yours.

J.P.
Click to expand...


Smokin Joe is right. Some parts of a newer home come with a type of warranty, most new roofs do, and your trusses should too. If you cut an engineered truss, you may (or probably will) void any warranty that may be in place. Every certification class for installers will tell you NEVER cut an engineered truss. It is your house tho, but be careful. I install (and sweep) offsets in houses with 8' ceilings on almost a weekly basis and they look fine, draft fine, and are no big deal to sweep. Also much less expensive than going thru the wall and up
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If it is brand new with warranty,but iam pretty sure its not because he is asking the question.I have been wrong before.I have built stair cases were you need a large opening through the truss with no big deal.
 
Cutting up into a structure of conventional rafter & ceiling joist construction is one thing...not too tough for a skilled carpenter to accomplish. Cutting up into a structure put together with factory-built trusses is another animal entirely, and not nearly so straightforward. If it's really a truss you're talking about up there, I'd highly recommend you find a way around it. Rick
 
fossil said:
Cutting up into a structure of conventional rafter & ceiling joist construction is one thing...not too tough for a skilled carpenter to accomplish. Cutting up into a structure put together with factory-built trusses is another animal entirely, and not nearly so straightforward. If it's really a truss you're talking about up there, I'd highly recommend you find a way around it. Rick
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most truss are factory built from the 1950s and on. As long as there is enough room to work up there that would cause more problems than anything
 
Well, okey dokey then...I'll go out and take my sawzall to my engineering degrees right now. %-P Rick
 
While installing our chimney we encountered the same problem. I thought about cutting the rafter (actually my house has manufactured trusses in the ceiling). Since I work for an architectural/engineering firm, I ran this by one of the structural engineers, based on what he told me, for get it. It can be done but the amount of work was more than it was worth. I am an electrical contractor so construction work does not bother me, but the work required was not worth it.

Basically you have to reinforce (double up) the two structural members which the new load will be transferred too. They must be reinforced their entire length or where each side of the modification rests on a supporting (load bearing) wall. For me that was a lot of work. Not to mention that was just for the ceiling, the roof deck basically required the same type of modification, but from peak to exterior wall.

Again way more that it was worth to me.

The engineer is very good but also very reasonable, he is a farmer and is very handy. I have know doubt he was not pullying my leg.

aussieblake
 
smokinj said:
SmokinJoe said:
There is no way to cut or modify a truss. If you do you need an engineer to re-design the whole thing.

Sorry, but any competent builder should know this.

Especially if you plan on cutting through the bottom chord. You essentially remove the stability of the truss and comprimise that section of the roof system.

I don't mean to be a party pooper. But I would just use some offsets or try and reposition the stove if possible.

Now, you may cut the truss and nothing will happen for years. The choice is yours.

J.P.
Click to expand...
Just build a header,its done by competent builder everday without an engineer. Sorry but it pretty eazy but i think he is just going through the wall
Click to expand...

If he were cutting into a roof rafter or a ceiling joist then a header would work after he doubled up the adjacent framing members and built an appropriate header to carry the load. That is no big deal.

However when you cut into an engineered truss, even one made in the 1950's you essentially weaken the whole thing and completly change the dynamics and ability of the member to carry the loads it was specified to carry as well as adding to the instability of the remaining members since there is basically a localized failure in the roof system.

I am not an engineer. I was a finish carpenter for 12 years before I became a furniture maker. I have seen my fair share of failed inspections due to folks doing what is being recommended here.

I don't understand how some people can be so adamant about fire safety and proper clearances for stoves but yet so cavalier when it comes to folks whacking out framing members in order to install a chimney.

Be safe, ask an engineer or go around the truss.

J.P.
 
Corey - yes, useful discussion.

I think I'll just have to convince my wife that elbows won't look that bad ... I was looking for a general consensus or sense of what the majority of folks here would do and got that - use some elbows and move out!

I really do not want to cut the truss (even though 2 of 4 certified chimney sweeps/installers that came out to the house to give me an estimate said no problem - they do it all the time). I'm also an engineer and know that there's got to be a way to successfully frame around it and still support the load - just seems like way too much hassle. Incidentally, 2 or 4 potential installers also wanted to increase the pipe diameter over manufacturer recommendations to supposedly increase draft, one admitted to burning coal in a stove not designed for such, one of four said I'd need a permit, the other 3 said no, and 0 of 4 could answer questions about the differences in different brands of chimney pipe (430 stainless vs. 304, different insulation types, etc.) The price difference between using elbows and going out the wall and up the side of the house is astounding - not quite, but close to double the materials cost.

Thanks again - the workshop picture not only makes me jealous, but helps the wife unit understand what the setup will look like.
 
aussieblake said:
While installing our chimney we encountered the same problem. I thought about cutting the rafter (actually my house has manufactured trusses in the ceiling). Since I work for an architectural/engineering firm, I ran this by one of the structural engineers, based on what he told me, for get it. It can be done but the amount of work was more than it was worth. I am an electrical contractor so construction work does not bother me, but the work required was not worth it.

Basically you have to reinforce (double up) the two structural members which the new load will be transferred too. They must be reinforced their entire length or where each side of the modification rests on a supporting (load bearing) wall. For me that was a lot of work. Not to mention that was just for the ceiling, the roof deck basically required the same type of modification, but from peak to exterior wall.

Again way more that it was worth to me.

The engineer is very good but also very reasonable, he is a farmer and is very handy. I have know doubt he was not pullying my leg.

aussieblake
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He is going the eazy route 2- 45s,but it is all ready on the out side wall (load bearing) thats what makes this job eazy. I put a 1/2 2nd story on my house and cethral on the other side all passed inpection and i know this work not for every one.Again he is already on the out side wall(load bearing)
 
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