NO ONE KNOWS????? ANY INSTALLERS?????: Is the 2" Air Clearance Between Chimney Air Kit to Framing

[njkev]

I would be more concerned with the lack of drywall in the chase to retain the insulation.

Correct me if I am wrong......but I don't believe there is any requirement for drywall in the chase. The insulation is not loose as the (combustible) paper side of the insulation is stapled to the studs. The "glass" portion of the insulation certainly won't burn even if that were to ever touch the flue. The pipe is the required double-walled SL300, and I am told it actually remains reasonably cool to the touch. The fireplace is a ZC, but the manual does require 1" clearance (for air flow) around the back and sides of the galvanized steel box. I have ~ 1" in the back and about 18" on the sides. I will certainly consider using a few of those steel insulation securing rods after I staple the insulation up between the studs above the fireplace before sheet rocking, for added safety.

From this description and the picture, it sounds like the paper on your insulation is to the outside. This is backwards and could cause a moisture problem down the road. The paper should go towards the heated side (inside) of the house.

Check out www.buildingscience.com for some great articles on insulation (Thanks BeGreen). You want to avoid having the dew point occur within the insulation.

Good luck.


Pete

Hi,
I just got home and took a close look all the insulation in my chase. The insulation on the back and side walls (exterior wall) is all PAPERLESS insulation. That means there is no risk of fire if the insulation were to become loose and fall against the unit. The builder had some brains I would imagine! I took clearance measurements between the unit and each of the three wooden vertical studs behind the unit (see photo I had posted earlier). The left & center studs measure 1 1/8 inch, and the right stud measures 3/4". The 3/4" is obviously less than the 1" stated in the manual...but I imagine it is OK????? The insulation that I removed from above the fireplace (inside wall) was all with PAPER; should I replace that with PAPERLESS??. Please comment.

Thanks,
kev

 

[Shane]

So long as the insulation is securely fastened I don't think it will be going anywhere. In my old house I opened up the chase and the insulation (paper backed) was still where they put it when the house was built 30 years ago. In technical terms the 3/4" of an inch is against mfg install instructions and therefore against code and you'll likely not find a sane professional who will tell you it's ok for fear of liability. I will tell you in the real world I've seen heavily used (overfired) woodstoves, fireplaces etc. that have the unit and or chimney actually touching framing, with combustible materials (paper, wood shavings, chunks of 2x4) , basically all kinds of scary crap and they don't burn down. If I were you I would get a piece of .22 gauge or similar sheet metal and slide it between the unit and the wall and attach it to the studs. This will add an added layer of protection against the radiant heat for the 3/4" clearance issue and also ensure that the insulation does not ever sag and invade the airspace. If you want to do to a "T" then you'll need to get rid of that 1/4" on the stud. Since you have it opened up etc this might be the best way to go as you don't know how picky your inspector is going to be.

 

[njkev]

So long as the insulation is securely fastened I don't think it will be going anywhere. In my old house I opened up the chase and the insulation (paper backed) was still where they put it when the house was built 30 years ago. In technical terms the 3/4" of an inch is against mfg install instructions and therefore against code and you'll likely not find a sane professional who will tell you it's ok for fear of liability. I will tell you in the real world I've seen heavily used (overfired) woodstoves, fireplaces etc. that have the unit and or chimney actually touching framing, with combustible materials (paper, wood shavings, chunks of 2x4) , basically all kinds of scary crap and they don't burn down. If I were you I would get a piece of .22 gauge or similar sheet metal and slide it between the unit and the wall and attach it to the studs. This will add an added layer of protection against the radiant heat for the 3/4" clearance issue and also ensure that the insulation does not ever sag and invade the airspace. If you want to do to a "T" then you'll need to get rid of that 1/4" on the stud. Since you have it opened up etc this might be the best way to go as you don't know how picky your inspector is going to be.

Hi Shane,
Thanks for your reply. The PAPERLESS insulation is actually just "compressed" between the studs, and it hasn't really moved in 10 years since my house was built.

That 22 Gauge sheet metal is fairly thin...right? Home Depot or Lowes should have some nice size sheets? I will probably have to get two or three long sheets and try to secure it the best I can to any stud that is visible around the unit. You can see from the photo (previous post), that there isn't much room to get anything wide around back of the unit at this point.
I'm sorry...I am not sure what you mean by a "T". There is no way I will be able to get behind the unit to shave down that right stud by 1/4" anyway.

I tried to get in touch with the installer earlier today to raise my concern about this too....but he didn't call me back. I intended to close up the wall this weekend once and for all as my wife is tired of seeing the "gaping" hole in the wall for a over a week now! I am SO tempted to just say "It's good enough", and call it a day!

Thanks,
Kev

 

[Hogwildz]

You could also put Micore in there. It would protect better, and does not transfer heat like the galv. does.

 

[njkev]

You could also put Micore in there. It would protect better, and does not transfer heat like the galv. does.

I would, but don't where to get Micore in short notice. I do have two 3x5 sheets of 1/2" cement board, but that is too thick and I can't find a Lowes or Home Depot around here that carries 1/4". I would not be able to get a single sheet of anything back there now anyway. :-(

 

[Shane]

If you can't get back there to notch the 2x4 and the insulation hasn't moved for 10 years then I'd probably just close it up too.

 

[begreen]

If you can get a short nail every 8-12" on alternating studs, you can use light gauge wire in a zig-zag fashion, from nail to nail, to hold in the insulation.

 

[fossil]

Chicken wire & a staple gun. Rick

 

[Saw-dust]

Chicken wire & a staple gun. Rick

Yea, chicken wire is good for lots of stuff. Easy to work with too. they make 2 foot wide short rolls you can get for less than $10.

 

[njkev]

Thanks to everyone that replied to my post! I appreciate all of the advice!

I pulled the fireplace forward 1/8 inch more, compressed any stray insulation fibers sticking out between the studs with a long flat piece of wood , and put in those wire insulation retainers between the studs from ceiling of chase down to as far as I could reach down behind the unit. The clearance to left and center studs is close to 1 1/4", and the right is 7/8". It turns out that the right stud is "warped". At bottom of the right at back of unit measures 1 1/4" to that same right stud. I think I am OK. There is the necessary open space behind the unit for airflow, and I have over 18" on each side of the unit. I finished framing it this weekend, added the (provided) Micore kit to the front of the unit, put back the interior wall insulation (WITH wire retainers), and sheet-rocked the walls. Just need some joint compound/spackle before I can build the extended hearth, tile, and add a mantle. I'll add more photos soon.