Insulating around Selkirk Insulation shield

[tankd0g]

I'm just putting the finishing touches on my garage and I realized I'm getting a massive draft out of the gaps around the insulation shield of the Selkirk chimney. I didn't tape the vapor barrier to it and it just has roxul insulation pushed around it. The easiest thing to do would be spray foam but I've seen what that stuff does if you hit it with a flame. Can anyone tell me what they did to seal around their chimney?

 

[Highbeam]

How big are the gaps? I've caulked them shut but a good chimney support box system should seal up pretty tight. You can use anything so long as it is outside of the usually 2" CTC.

 

[tankd0g]

How big are the gaps? I've caulked them shut but a good chimney support box system should seal up pretty tight. You can use anything so long as it is outside of the usually 2" CTC.

It's a round cylinder in a square hole so there's 3 or 4 sq. inches at the corners above the decorator trim ring. It's really not the best design in the world. There's a gap where the shield touches the chimney also that I'd have to silicone to be air tight but that might be necessary to vent any heat buildup.

 

[MagKarl]

Can you swap out the round for a rectangular support box? That's what I have.

 

[tankd0g]

Can you swap out the round for a rectangular support box? That's what I have.

Maybe I installed it wrong but it is a rectangular support box with a round sleeve that slides over the pipe to keep the insulation from touching the pipe.

You can't really see in that picture but the way I have it installed, the flange of the attic insulation shield sits on top of the 2x4 framed box, there is an insert inside the attic insulation shield that drops 4" down inside to keep the shielding within the framed box all the way to the cieling support which is attached to the bottom of the framed box. Air is able to enter the top of the sleeve and come out above the trim ring of the cieling support. If I spray foam it I will be sealing the gap between the inner and outer sleeves of the attic insulation shield within the framed box. The other option would be to put a gasket on the decorator trim ring and press it against the drywall (I left about a 1/2" gap because I had to install the drywall after the pipe was put in since there's no access to the attic space). If I do that though I'll probably get moisture in the drywall at some point.

 

[MagKarl]

Those parts don't look anything like mine, sorry. Google images has lots of pics of rectangular chimney support box installations, you might look at some of those for hints.

 

[tankd0g]

Those parts don't look anything like mine, sorry. Google images has lots of pics of rectangular chimney support box installations, you might look at some of those for hints.

Thanks, I have an email into Selkirk support, I'll see what they say about it.

 

[Highbeam]

The simpson boxes are way cooler. Here's mine. It's a support box and insulation shield combined.

 

[MagKarl]

That's pretty much what mine looks like Highbeam.