Rock Wool Insulation

[GaryS]

I'm going to try to get my liner in this weekend. I was thinking of insulating the very top and at the bottom around the tee with something to create a dead air space between the liner and the old flue. Would rock wool work? I'm having trouble finding any sources online. My local dealer didn't have any ideas.

I'm putting a cap on the top and a collar at the thimble so that should seal it somewhat.

 

[oconnor]

I just insulated my entire basement with ROXUL, a rockwool product I bought at Home Depot. Meets flamability spec to 1200 F, but a chimney fire is hotter than that, so I don't like the idea of using it toucking my liner.

I know many folks like the idea of insulating the block off plate and top, but I still don't understand why. I would focus on sealing the collar, chimeny top and clean out hatch with stove cement or high temp RTV. The advantage of shoving insulation in there isn't the R value of the insulation, it's the air sealing that results from not losing heat thru air movement up the flue. I would consider insulating the liner with a wrap, air sealing the top/bottom well but don't see the value in the rockwool top and bottom. With the liner at 1200F, heat is going to transfer regardless.

 

[velvetfoot]

Is Roxul a Canada-only product? I don't recall seeing it at my HD.

 

[oconnor]

Nope. I found it thru the HD website. It's firestop insulation.

 

[doug60]

I have a 8 inch liner in a 12x12 clay liner (outside chimney)
I filled the void top to bottom with rock wool.
Its been 20 years & 4 different stoves .
No issues.

 

[pybyr]

I'm going to try to get my liner in this weekend. I was thinking of insulating the very top and at the bottom around the tee with something to create a dead air space between the liner and the old flue. Would rock wool work? I'm having trouble finding any sources online. My local dealer didn't have any ideas.

I'm putting a cap on the top and a collar at the thimble so that should seal it somewhat.

I have heard of people using vermiculite or perlite, and just pouring it in, although you have to make sure the bottom end is tight so that it doesn't all spill out the lower end, and also make sure that the top end is tight so that water does not get in