Rock/Mineral Wool where to buy?

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burleymike

Feeling the Heat
Sep 17, 2010
279
SE Idaho
I am slowly trying to get my fireplace ready for the insert which will be here Thursady. I want to put a blanket of rock or mineral wool around the firebox and on the block off plate. Only problem is I have called nearly everybody within 100 miles and nobody knows where I could get some.

I remembered when I gutted one of the bedrooms a few years ago having a batt of rock wool fall out of the ceiling when I tore it down. I went up in the attic and it turns out they used a few more of them. This is from the late 1950's and it is wrapped with paper. I got a sample of it and put a propane torch flame to it. Only the tip of the flame would melt it. It did have a slight plastic burning odor so I have a feeling it has some binders in it. It did not smell or melt as badly as fiberglass does though.

Am I crazy for thinking about taking that batt of wool out of the attic, removing the paper and using that to insulate the fireplace and block off plate?
 

DAKSY

Patriot Guard Rider Moderator
Staff member
As long as you take the paper off you will be fine.
We actually gave up on the block off plates & cram unfaced
insulation in the damper area & under the cap - around the SS
liner & we have NEVER had any issues.
Fiberglass does not burn, melt or out-gas at wood stove operating temperatures.
If it did, it wouldn't be considered safe for door gasketing material.
 

phil san

Member
Jul 15, 2008
140
South Shore, MA
You want to feel safe and secure, use rockwool. I can put a propane torch to it and it does nothing. Used it for insulating the backwall of my fireplace and in addition to a metal block off plate stuffed batts of rockwool in there. Air tight and going on 3 seasons for a pellet FI.

Google - acoustacal rock wool. Comes in 24" x 48" firm bats. Cuts easy, holds shape and works. For 6 bats expect to pay about $70 shipping included. Youl'll get it in 3 days.

Then you will know what you have as oppossed to some old stuff from the atic.
 

jstellfox

New Member
Jul 15, 2010
97
PA
Search Ebay for Kaowool. There is a guy on there that sells it by the square foot. I purchased 2 sqft from him to use against my ss pipe. Its good to 2100 degrees and I can put a torch to it and it does nothing...no burn, smoking or melting!
 

johnsopi

Minister of Fire
Nov 1, 2006
696
MD near DE&PA;
We use cremic wool/KO wool at work. Good at 1000c
 

oconnor

Minister of Fire
Nov 20, 2005
1,074
Nova Scotia
DAKSY said:
As long as you take the paper off you will be fine.
We actually gave up on the block off plates & cram unfaced
insulation in the damper area & under the cap - around the SS
liner & we have NEVER had any issues.
Fiberglass does not burn, melt or out-gas at wood stove operating temperatures.
If it did, it wouldn't be considered safe for door gasketing material.
Daksy, do use a supplier of fiberglass that produces batts with no binding agents in it? Anytime I've applied heat to regular fiberglass batts it makes an awful smell. The glass isn't what stinks, its the rest of the stuff they use to make it.

If you want rock wool, your local building supply store will stock fire rated rock wool used in commercial buildings when walls need a fire rating. One brand name is Roxul.
 

Rudyjr

Feeling the Heat
Nov 25, 2008
362
Central Ohio
A local insulation contractor in our area gave me a piece of Roxul (rock wool) left over from a commercial job for my install. Just stopped in and told them what I was getting ready to do and asked if I could purchase some. I still put in a block off plate, probably overkill but really not too tough to do. It has worked perfectly for me
 

burleymike

Feeling the Heat
Sep 17, 2010
279
SE Idaho
Every bit of spare time this afternoon went to calling insulation contractors, commercial construction companies, and building supply houses. Only one supply house could order some and it would have to be a minimum order. I went ahead and pulled the batt of rock wool out of the attic. I pulled the paper off of it and rolled it up it will be better than nothing. I will not have enough batt to do behind the insert but that is ok. I do have 4" of loose fill rock wool in the attic I could use for behind the insert but I don't want all that dust floating around the house.
 

joefrompa

Minister of Fire
Sep 7, 2010
778
SE PA

firefighterjake

Minister of Fire
Jul 22, 2008
19,079
Unity/Bangor, Maine
burleymike said:
Every bit of spare time this afternoon went to calling insulation contractors, commercial construction companies, and building supply houses. Only one supply house could order some and it would have to be a minimum order. I went ahead and pulled the batt of rock wool out of the attic. I pulled the paper off of it and rolled it up it will be better than nothing. I will not have enough batt to do behind the insert but that is ok. I do have 4" of loose fill rock wool in the attic I could use for behind the insert but I don't want all that dust floating around the house.
I realize you probably are all set . . . but I had good luck checking with the local plumbing and heating company that professional plumbers use to buy their supplies . . . bought a 3 x 5 rigid sheet of rockwool (or similar product) for less than $15 . . . the stuff is easy to cut with a utility knife and stays in shape with very little dust. The guy at the counter called it zero clearance insulation . . . can't recall the exact brand name though.
 

midwestcoast

Minister of Fire
Oct 9, 2009
1,745
NW Indiana
I had the same issues and did the same thing; pulled batts of rockwool out of my attic for over the block-off plate and walls of the fireplace. If it saves a hassle and a few bucks, why the heck not? Attic is 18" deep with cellulose now so no harm done there.
 

joefrompa

Minister of Fire
Sep 7, 2010
778
SE PA
Nice. Thanks for the link. Any reason for NOT using the soft stuff besides easier to deal with? I'd just shove it in there around the stove as much as possible with the soft stuff (and up around the chimney liner).

Joe
 

johnstra

Feeling the Heat
Sep 6, 2010
334
Northern Colorado
The Roxul from ATS Acoutics is what I got... great stuff. The bats seem much easier to work with than the boards.
-john
 
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