Insulating a direct vent gas fireplace.
Hi, i was wondering if anyone could give me some guidance on how to properly insulate this space. I recently removed out our old gas fireplace to find that the insulation was done quite poorly which had led to mold, wet plywood e.t.c I live in Toronto, where we have freezing winters and very humid summers. Im confused as to where exactly should be insulated. The bottom half exterior chase part i used mineral wool , applied 6 mil poly vapour barrier and will drywall.
Now this top cavity, im lost?
(a) if i insulate this exterior top cavity do i also vapour barrier this and drywall?
and
(b) do i also insulate the interior wall where the three osb sheathing wall cavities are?
Really not sure how to to attempt to insulate this top half, any advice would be appreciated. Thankyou.
Replies
Sorry not sure why two of the pictures have gone sideways.
frame in a little ceiling in the space, insulate, vapor barrier, and drywall. you can use rock wool like you used in the outside wall. make it as thick as you can.
the stud wall three bays with OSB outside above should be insulated, and vapor barrier above the level of your new ceiling (vapor barrier along the inside surface of the insulated space.)
That wall really could use a header over the opening.
seal all the vapor barriers together.
Assuming you are putting the stove (or a replacement ) back in the space? Also assume you have a zero-clearance model intended for close installation. follow any instructions associated with the new stove.
Thankyou UncleMike42 for taking the time to respond. I do have a header it just got cut off in the pic. I will be adding in another gas fireplace. Your method on insulating this awkward spot sounds great. Im thinking the builder might have done a double vapour in there as there was a lot of water marks and the plywood was just soaked. Again thankyou for your advice.
UncleMike42 just a quick question. When you wrote frame a ceiling , insulate, vapor, e.t.c did you mean place vapor here straight across (blue line) under the insulation then drwall? or to vapor each individual space seperatly. Thanks again.
the first.
the vapor barrier should form a continuous surface on the inside of the insulation, and just outside of the drywall. (related to inside the occupied space, going to the outside)
you can cut the vapor barrier long and tape to the next surface.
Working on it now, so thankyou for the quick response. Appreciate it.
You also can look for stuff to spray on the outside of the bricks to help keep water out.
I think you want a water repellent, not a water proofer.
Something like this:
https://prosoco.com/product/siloxane-pd/
This maybe what i need, thankyou again for your help.