How to insulate my liner

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DB Cooper71

New Member
Mar 25, 2019
24
Minnesota
I've got my new fireplace insert installed. I've been told by another member/staff member here that it needs to be insulated to meet UL1777 code. That is correct beyond a shadow of a doubt in my situation. I'm going to insulate it for code/safety reasons. I've got 2 options. I either pull the insert back out and reinstall the liner with blanket insulation, or pull the insert, make a catch plate and use the pour-in type.

So after doing some more research, I think the pour-in insulation would be a PITA. Until I make a catch plate and secure it in there. Mix several buckets of the stuff. Cart it up a ladder one bucket at a time, and then pour. It might be easier to just reinstall it as a blanket insulated liner. Do you think that I can get a properly blanket insulated liner stuffed in there? The wire mesh covering might keep it from ripping.

Here's what I'm working with.

The flue is 6" x 8" inside dimensions, and the liner is 5" x 7" ovalized flex 316Ti. It went down very easily the first time. I fabbed a sheet metal cone with a rope attached and had the wife pulling from the bottom. The blanket supposedly adds 1.5" to the outer diameter of the liner. Those numbers don't work, but the insulation is soft and might squish through there. I'll double clamp the leading end to make sure it's secure and wire wrap the mesh like crazy to keep it from ripping. The biggest problem I see is that there is an offset in the flue. Making those corners worries me. I don't want to struggle to get it in place, only to find shredded insulation.

Which do you think is the better option? Can I get the blanket insulated liner in there without destroying the insulation? Should I just pour it and do my best not to make a mess of that?

I don't need opinions on whether or not it needs to be insulated. It absolutely does to meet code requirements.

Thanks for all opinions and experience you've got to add.
 

MAD MARK

Feeling the Heat
Jan 31, 2016
352
Pittsburgh PA
Pull insert. Pull the liner. Insulate on the ground the proper way. Reinstall liner. Reinstall insert.

You can get thinner insulation that wont add 1.5" total. Will be tight fit regardless.
 
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DB Cooper71

New Member
Mar 25, 2019
24
Minnesota
Pull insert. Pull the liner. Insulate on the ground the proper way. Reinstall liner. Reinstall insert.

You can get thinner insulation that wont add 1.5" total. Will be tight fit regardless.
That's what I'm thinking too. The manufacturer says the 1/2" blanket will actually add 1.5", not the expected 1". The 1/4" stuff doesn't meet zero clearance code.
 

double-d

Feeling the Heat
Feb 8, 2011
322
Northern Michigan - Mio
The reason it is 1.5", is the insulation Blanket is 24" wide, so it ends up overlapping. You can trim it down so it only butts up to it's self to reduce the extra 1/2" of thickness.
 
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DB Cooper71

New Member
Mar 25, 2019
24
Minnesota
The reason it is 1.5", is the insulation Blanket is 24" wide, so it ends up overlapping. You can trim it down so it only butts up to it's self to reduce the extra 1/2" of thickness.
That's exactly what the guy said when I spoke with him on the phone this morning. If I decide to go that route, I'll have to do that, but leave the paper longer to overlap and protect the edges of the insulation.

Thanks for the insight! This is the kind of good info I need.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
18,638
central pa
Pull insert. Pull the liner. Insulate on the ground the proper way. Reinstall liner. Reinstall insert.

You can get thinner insulation that wont add 1.5" total. Will be tight fit regardless.
Thinner insulation won't bring it up to code
 
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bholler

Chimney sweep
Staff member
Jan 14, 2014
18,638
central pa
That's exactly what the guy said when I spoke with him on the phone this morning. If I decide to go that route, I'll have to do that, but leave the paper longer to overlap and protect the edges of the insulation.

Thanks for the insight! This is the kind of good info I need.
It is going to be tight but if you have 6x8 the whole way it should work
 
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DB Cooper71

New Member
Mar 25, 2019
24
Minnesota
I guess this thread can be closed. I've ordered the 1/2" blanket insulation with clamps and wire mesh. I'll get it reinstalled once that gets to me.

You know what they say..."We do it nicest, because we do it twicest!"
 
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