Block Off Plate Materials?

[80s Burnout]

Hi.

I will be installing a block off plate and need help on appropriate materials. I went to the local hardware chain and got some galvinized sheet metal that is used to build heating ducts - like for forced hot air system.. That's all they had. I am planning to snip this to size and install. Can I use something like this? I'm not sure of the gauge. All I want to do is keep hot air from escaping up the flue. I have installed a 6" flex liner and will have a cap on the top of the chimney, but want to block off at fireplace damper too. How best to secure the block-off plate as well? I got some high temp. fireplace sealant and plan on using that around the edges?

Will my plan work? Is that galvi sheet metail suitable material?

Thanks.

Burnout

 

[RAY_PA]

sounds good so far, I cut 'ears' in mine, to fold down, drilled a few of them ans used screws to hold in place, then sealed the edges like your planning. I had some koawool laying around, so I glued it to the top side of the block-off plate before I secured it in place.

 

[BrotherBart]

Tapcons work well. They are masonry screws. You drill a hole for them in the bricks and then screw'em in. HD, Lowe's and hardware stores have them.

 

[oconnor]

Is there any concern about the "galvanized" part? I know it's a no go for wood stove smoke pipe, is it OK for a blockoff plate?

 

[Creek-Chub]

No concern about the galvanized, but I can tell you the "heating duct" material is quite a bit thinner than the 24 or 26 guage recommendation on here for a block-off plate. I can't say if it will matter, but it definitely isn't the same stuff. I was able to find enough 24 guage material at Lowes to make my block-off plate. Try there, and if you're curious, compare it to the duct stuff. Apples and oranges... Again, I don't know enough about it to say that it matters much either way...

 

[BrotherBart]

Yeah I use the sheets from Lowe's. Eight bucks ain't cheap but it is heavy enough. Galvie has to get a lot hotter than a block off plate gets to kick fumes.