Question about Block-off Plate

[eshwars]

Hi all,

I'm new to this forum and am currently shopping for a wood burning insert for our fireplace. I've found the information here very helpful! Thank you all for sharing your knowledge!

While doing some background reading, I stumbled onto the very informative article about installing a block plate and I have a question: why does the plate actually need to be sheet metal? Can't it be chicken wire with rock-wool behind it? The reason I ask is that the chicken wire is so much easier to work with (and cut down to size) than sheet metal? Isn't the job of the sheet metal just to hold up the insulation?

Thank you in advance!

 

[bholler]

Hi all,

I'm new to this forum and am currently shopping for a wood burning insert for our fireplace. I've found the information here very helpful! Thank you all for sharing your knowledge!

While doing some background reading, I stumbled onto the very informative article about installing a block plate and I have a question: why does the plate actually need to be sheet metal? Can't it be chicken wire with rock-wool behind it? The reason I ask is that the chicken wire is so much easier to work with (and cut down to size) than sheet metal? Isn't the job of the sheet metal just to hold up the insulation?

Thank you in advance!

No the sheet metal is to stop air movement. Insulation will not do that

 

[weatherguy]

It's not that hard to make one with sheet metal, I did it and I'm not the most handy person in the world. I used a cardboard cutout then traced it over the sheet metal. The metal will deflect all heat back into the house, makes a big difference.

 

[eshwars]

I see. Thanks for the information!

 

[toddvogt]

Hi Everyone - I'm working with a contractor who is helping install a new woodstove (Woodstock Progress Hybrid in an existing fireplace with chimney that runs up the middle of the house) and would like your help double-checking what he's planning on doing for the block-off plate. Originally he proposed doing it with metal, but this week he shifted to recommending using fire brick secured with refractory cement (and obviously cutting the brick to fit around the liner). I understand from the Hearth.com forums that the purpose of the block plate is to stop airflow - and it seems that this approach could achieve that goal, but wanted to make sure it made sense for those with experience in this realm.

And one other point: recommendations on this site include putting insulation (Roxul (mineral wool)/kaowool (ceramic insulation)) above the block-plate. Is that only needed for external chimneys? Not sure what the benefit is for an internal chimney.
I've also seen some recommendations for insulation at the top of the chimney...wouldn't that just get wet/erode over time?

I greatly appreciate your help - thank you.

 

[bholler]

Hi Everyone - I'm working with a contractor who is helping install a new woodstove (Woodstock Progress Hybrid in an existing fireplace with chimney that runs up the middle of the house) and would like your help double-checking what he's planning on doing for the block-off plate. Originally he proposed doing it with metal, but this week he shifted to recommending using fire brick secured with refractory cement (and obviously cutting the brick to fit around the liner). I understand from the Hearth.com forums that the purpose of the block plate is to stop airflow - and it seems that this approach could achieve that goal, but wanted to make sure it made sense for those with experience in this realm.

And one other point: recommendations on this site include putting insulation (Roxul (mineral wool)/kaowool (ceramic insulation)) above the block-plate. Is that only needed for external chimneys? Not sure what the benefit is for an internal chimney.
I've also seen some recommendations for insulation at the top of the chimney...wouldn't that just get wet/erode over time?

I greatly appreciate your help - thank you.

Yes firebrick would work. But why would he want to do that? It is going to take far far more work. And no you don't need insulation at the top you do need an insulated liner though