Turning insulated chimney in attic as quickly as possible

[webbie]

We have a steep roof and a stove that is going near the eve - so we want to the chimney to jog over as far as possible inside the attic before exiting.....

Problem is that the ceiling support box I saw says to go up 18" with a straight pipe min. That means the first 30 degree can only be installed way up there.

Anyone have any experience with this? Maybe one brand allows turning before another, or perhaps by making a custom or cutting down an attic insulation shield I could turn sooner.

Turning as low as possible is important because the chimney can only slope 30 degrees, which the roof slopes 45 (12/12), so unless I start low, the two will "meet" before I get too high up in the attic.

While we are at it, any math whiz want to tell me how much closer together two lines - one at 30 degrees and one at 45, get together for each foot of run? Example: The lines start with 3 feet in between them.....how far is the run til they meet?

 

[Hogwildz]

Can you "jog" the chimney pipe over before it enters the attic? Sounds like no matter what you do, you wont have enough room inside the attic for the jog over. Unless of course you trim the attic shield down. How much would you have to trim off? How deep is the attic insulation?

 

[webbie]

I can jog a little inside, that will help somewhat with initial clearance from the joists to rafters.

There is a full 10" or more of insulation - but the 30 degree can be installed parallel with the ceiling joints, in other words I don't have to clear the joists before turning. And insulation can be cleaned out of that area - even a home made insulation shield can be installed. It would be nice to install an 9" section and then the 30 degree.

This might be something I have to get a fax from the engineering dept for......

 

[Hogwildz]

Whats the purpose of the jog? to clear the rafters? Or is this the chimney you were installing that is near the roof valley? Would 2- 45's give you better clearance?

 

[tutu_sue]

Craig, I have seen an offset chart in the Simpson Duravent catalog that you can download from their site.

 

[webbie]

Hog, it is the valley install - and the reason is twofold or more - to get away from the valley, and also to get as much pipe in the attic (going up toward the peak) before I have to go up through the flashing because that means less pipe outside. As it is, I will have to resupport the pipe outside and probably have 8 feet about the flashing. If I went straight up, or a slight jog, I would need 12+ feet of chimney sticking up through the flashing.

Enclosed pic shows how straight up (1) would exit roof low, and pipe which jogged over inside the attic would exit closer to peak.

 

[Hogwildz]

Man you picked a sheety place to run that LOL.
You def want it at the higher spot. The further away from the valley the better. Don't want to create any kind of possible water damming near the valley. Not to mention, wanter coming off the high side of a valley during a hard rain runs sideways and is just another potential possible leak problem at the flashing.
I am having a tough time picturing 2-30's in the set up, wouldn't you get higher up through the roof with 2- 45's and a longer run of straight pipe in the attic?
Any way you look at it, that going to be a motha to get to top and clean.

 

[begreen]

I don't think there are 45's in classA. Are there any other possible locations or is this it?

 

[grizzly2]

Craig, if you measure horizontaly over 3' where the rafter intersects the top of the outside wall, it will be 3' staight up to the roof, given your 12/12 pitch. If you install your pipe at 3' horizontal from the wall location and have a 30* elbow at attic floor (or top of the ceiling joist) level and proceed upwards with pipe at that 30*, you are moving horizontaly at 2/3 the rate of the rafter. Therefore you will hit the rafter after gaining 2" horizontaly for a total of 5" from the outside wall. The total height (not length) of the pipe in the attic will be 5'. Measuring 45* up the slope of the roof from where the roof is over the outside wall should be about 7" up where the chimney will come through. :roll:

 

[Hogwildz]

Welp, Begreen, your right again.
Just found this on Duravent's site. Apparently in the U.S. NO all fuel chimney is allowed to use 45 degree elbows per code.

(broken link removed to http://www.duravent.com/docs/bulletins/2008/45_elbows_product_bulletin.pdf)

 

[webbie]

Yeah, 30 is always max with masonry or metal chimneys. It is really just about the only place in this entire house to put a chimney. I will be able to clean from the bottom, I think.

I will check the old fashioned way - use a 2x4 in the attic which I can hold at a 30 degree angle and see where that gets me.

Grizz, that sounds about right. I am starting about exactly 3 feet in!

 

[Hogwildz]

Craig, why not buy a couple 6" adjustable galvanized elbows (set a 30 degrees each) at Home Depot and a straight 5' section also, relatively cheap, and use them as a template for what you are trying to achieve?
I did this for a template for the layout of my insert liner and it worked well.

 

[webbie]

Sounds like a plan....

 

[Burd]

Can you put it where the sewer vent is,That way you can all most go straight up with your stove pipe.And your away from your valley. It not that hard to move sewer vent. This also puts you away from the second floor on the right. Hope this will work for you

 

[webbie]

I think it will work as planned as long as I can turn soon after I come out of top of ceiling support, and one friendly maker here already told be I can. Also, since it runs up between the rafters which are 2x10, that gives me more room also. So I do have some clearance. I'm going clean out the insulation and mock it up.......nothing like putting my face in the place. I can easily do the job myself, except I suck at ripping up and replacing shingles, so I'll call in someone to help with that - maybe have him install a solar attic fan at the same time - I don't relish being high up on the 12/12 roof.

 

[begreen]

Good plan. We don't want webwidow taking her handle too seriously. ;-)

So what stove are you considering?

 

[webbie]

Maybe Morso 3410 - 8" from rear wall and very small profile - it is actually against a wall in our breakfast area!

 

[webbie]

Good idea - things are always better when you are horizontal~~~~~~

 

[seaken]

My approach would be to plot it on a piece of paper. Using 1/4" graph paper always works good for me, along with a architects scaled ruler, and a pencil. You can figure it all out at your kitchen table using a scaled drawing.

Anyway, it is not required to use the manufacturers attic insulation shield. You can box it in with a chase. So, go ahead and place your 30* elbow as soon as you can, making sure you keep the 2" clearance to the ceiling joist. Use an offset support, and maybe even a roof support kit, under the flashing to stabilize the pipe after the offset. We find the roof support kit the best (this is a piece that bolts or straps to the pipe and has adjustable "wings" on it to allow you to place it on the pitched roof). It will be hard to keep the pipe plumb without it.

Sean

 

[grizzly2]

- I don't relish being high up on the 12/12 roof.

I feel your pain. Roofed my house 30 years ago. Hired it done last year. Older and Wiser. :coolsmile:

 

[Hogwildz]

- I don't relish being high up on the 12/12 roof.

I feel your pain. Roofed my house 30 years ago. Hired it done last year. Older and Wiser. :coolsmile:

I always found the steeper pitched roofs easier on my back, less angle of bending.
With enough roof jacks & planks its pretty easy.
I find I miss it sometimes, roofing & metalwork in general.
But then the neck, back, knees and everything else remind me why I don't do it much anymore.