Block off plate troubles...

[Easy Livin’ 3000]

We'll be on season 3 or 4 this upcoming winter of our self install of our wonderful SBI insert in an old fireplace.

The smoke shelf is stuffed with roxul insulation, with a very half-azzed block off plate holding it up.

We'd love to install a first class plate, but the shape and depth of the hearth walls make it very difficult. It's angles are creating the challenge. We won't be pulling the stove, adding to the difficulty.

The goal is: airtight around the perimeter, with as small a hole around the liner pipe as possible.

I guess I am hoping for some anecdotes about how you did it, or perhaps just s moral support as I dive in again.

 

[mellow]

It isn't hard, just a pain to sit in the fireplace at odd angles installing it. Plenty of write ups already on the site how to do it so I won't get into that. Get a good pair of aviation snips and that will be half the battle, bending a thinner piece of sheet metal to conform isn't that bad.

 

[CaptSpiff]

I can't remember who here on Hearth.com suggested this, but it worked for me:

Don't be too concerned about the precise middle cut of the stove pipe hole in the block-off plate.
Treat it as 5 separate pieces of bent sheet metal pop riveted together.
Template out and bend a back piece, then the two side pieces, then the front.
Test fit the four pieces and clamp them to each other with mini clamps (clothespins worked for me).
You'll have a neat fit at the edges, and a big odd shaped hole opening in the center.
Now cut a rectangular piece of sheet metal that overlaps the four pieces by a few inches.
Now test fit and mark approx where the stove pipe will penetrate that rectangular piece.
Use the stove's appliance collar to pencil mark and then cut the round hole in the 5th piece.
When everything looked good, I used sheet metal screws to attach the 4 "bent" edge pieces to the perimeter wall, and pop-riveted the sheets to each other at their overlap.
Put lots of Hi-temp chalk in all the spaces. Slid my Roxul thru the odd shaped opening (plenty of room).
Then slid the 5th rectangular piece over the flex liner, lined up the insert, and pencil marked the 5th piece against the 4 permanently mounted edge pieces.
Plenty of slide room on the overlap sections so this is where you get a pass on any prior errors.
Pulled the insert (needed room) and attached the 5th sheet with about a dozen sheet metal screws (for removability).
Lots of slow tedious work, some cuts on my fingers, but it turned out perfect.
Hope that helps you.

The hurdle for me was trying to do it as one piece.

 

[Easy Livin’ 3000]

I can't remember who here on Hearth.com suggested this, but it worked for me:

Don't be too concerned about the precise middle cut of the stove pipe hole in the block-off plate.
Treat it as 5 separate pieces of bent sheet metal pop riveted together.
Template out and bend a back piece, then the two side pieces, then the front.
Test fit the four pieces and clamp them to each other with mini clamps (clothespins worked for me).
You'll have a neat fit at the edges, and a big odd shaped hole opening in the center.
Now cut a rectangular piece of sheet metal that overlaps the four pieces by a few inches.
Now test fit and mark approx where the stove pipe will penetrate that rectangular piece.
Use the stove's appliance collar to pencil mark and then cut the round hole in the 5th piece.
When everything looked good, I used sheet metal screws to attach the 4 "bent" edge pieces to the perimeter wall, and pop-riveted the sheets to each other at their overlap.
Put lots of Hi-temp chalk in all the spaces. Slid my Roxul thru the odd shaped opening (plenty of room).
Then slid the 5th rectangular piece over the flex liner, lined up the insert, and pencil marked the 5th piece against the 4 permanently mounted edge pieces.
Plenty of slide room on the overlap sections so this is where you get a pass on any prior errors.
Pulled the insert (needed room) and attached the 5th sheet with about a dozen sheet metal screws (for removability).
Lots of slow tedious work, some cuts on my fingers, but it turned out perfect.
Hope that helps you.

The hurdle for me was trying to do it as one piece.

Thanks! I've been scheming on this for a long time, and your experience lines up with my thinking. I'll try to remember to wear gloves!