Roxul used as "block off plate"

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Aug 20, 2014
128
Eden, NY
Hi Everyone,

So I know this has been discussed before, but I have a situation in which making a proper block off plate has not been successful for me. I have no way to attach any kind of metal plate to the area in my flue (the brick is covered with some sort of heavy metal that I cannot penetrate).

The flue has been open for two years now and I can tell I'm losing heat when the wood stove is in use and not in use. I was thinking of stuffing Roxul in the opening but I have read about what a mess it can create..If I stuff it in the opening, that will leave it exposed and I worry about fibers falling down and blowing around my living room.

Has anyone just stuffed it and left it without a plate? Has this caused any issues? or is there any type of alternative way to attach a metal plate without needing screws or nails?

thanks!
 
Has anyone just stuffed it and left it without a plate? Has this caused any issues? or is there any type of alternative way to attach a metal plate without needing screws or nails?
Yes many have done it. I usually use rivets in a case like yours or you could put the plate further down and use tapcons or lead anchors into the masonry
 
To me it seems those that are on the block-off plate bandwagon are going to get the most maximum sealing around the firebox. But in the end, what you really want to do is keep as much heat in the room than going up the flue But you are going to be ahead of what you are currently doing just by stuffing insulation up around the liner vent where it goes through smoke shelf. Just that alone is going to stop the draft from happening in your flue. Probably wont be 100% effective but far better than you were. You may get some rockwool dust that settles on top of the stove, especially at first, but will subside after a while. If you have a surround covering the opening you wont see it anyway.
 
To me it seems those that are on the block-off plate bandwagon are going to get the most maximum sealing around the firebox. But in the end, what you really want to do is keep as much heat in the room than going up the flue But you are going to be ahead of what you are currently doing just by stuffing insulation up around the liner vent where it goes through smoke shelf. Just that alone is going to stop the draft from happening in your flue. Probably wont be 100% effective but far better than you were. You may get some rockwool dust that settles on top of the stove, especially at first, but will subside after a while. If you have a surround covering the opening you wont see it anyway.

Yes, I'm not super concerned about getting it super air tight - I just want to keep as much heat in the room as possible. My main concern was the Roxul dust getting everywhere as I do not have a surround. Thanks!
 
Yes, I'm not super concerned about getting it super air tight - I just want to keep as much heat in the room as possible. My main concern was the Roxul dust getting everywhere as I do not have a surround. Thanks!

Well if you dont have a surround i would get a plate in there for sure
 
That's how mine is, approx 12" uparound the flue, and my entire fireplace is also lined/stuffed with Roxul. After installing I vacuumed the lose fibers and have had no problems.
 
I used magnets to hold my plate in place, you can then use something to seal the edges.
 
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I'm picturing a block off plate held in place with magnets!
 
Welding magnets would hold one up like nothing for securing. Great idea.
 
I'm doing the same with magnets. A buddy of mine had some 30 lb strength ones that he gave me and it works perfectly. I can take down if needed without any till tools or hassle.
It's not a great pic but it's all I have to show what I did

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Has anyone just stuffed it and left it without a plate? Has this caused any issues?

I just did this a few weeks ago, my fireplace also has that thick steel, where the damper was there is a perfect lip for the insulation to rest on, cut it big and cram it up there, stuff it north / south first, then the last few pieces east / west..... so far so good with me. I am not doing a plate, just insulation, reason being I do not mind a tiny bit of air flow going up around the insulation, my thinking is in case the flue collar ever leaks smoke it will hopefully trickle up.
 
Full year so far. They are rated for 30 lbs and I think I have 3 or 4 of them to hold up something that weighs a less than 10 pounds. So even if they do degrade, (which they shouldn't), it will take a long time.
 
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