Block off plate without the plate

[CK1]

Hey,

So I am about to install my new wood burning fireplace insert (Hearthstone Clydesdale) and I want to install a block off plate at the damper in a masonary chimney. I currently already have a fireplace damper in place that is farily large, but will be cutting a large square in to it, to fit the 6 inch pipe through. My question is, I'm not removing the whole damper just removing enough to fit the flue through, so I was thinking of resting some roxul safe'n'sound insulation ontop of the damper as my block off. Roxul seems to be rated to 2100f.

Anyways if I do that, do I really need an additional piece of steel under it (the damper will hold the roxul up), and the other piece of steel while would be nice to put in, based on my damper location, seems like it would be hard to put it there. I'd have to attach the plate of steel directly to the cast iron damper which seems like it would be tough to do with screws.

So bottom line, is roxul enough? Seems like it would be to me... but I only want to do this once ,and I'd like to do it right, without the installation driving me crazy.

 

[begreen]

Cast iron is pretty easy to drill and can be tapped if necessary.

 

[BrotherBart]

Personally I think between having the shroud on the insert, the rest of the damper frame above it and Roxul on top of the damper frame you are gonna be fine. Just be sure to pack Roxul around the liner opening in the damper frame. If it were a free standing stove in the fireplace I would say the block off plate is a must have.

 

[CK1]

Cast iron is pretty easy to drill and can be tapped if necessary.

Thanks, If you were to drill from steal into cast iron, what type of screws would you use? Just screws for metal you would find at home depot? How would you pre drill through the cast iron, with a masonry bit or a metal bit? Thanks

 

[begreen]

I tend to agree with BB here. With well packed Roxul, you will probably be about 80-90% sealed. But if you want to go all the way, you can drill the cast iron with a good quality metal bit. The screw type will depend on the metal thickness. You might be able to use a coarse thread self-tapping metal screw with a hex head. If not, it will need to be tapped and use a regular. metal screw.