How do I Insulate an old gas insert that sits on exterior wall?

[rashomon]

We have an old B-vent in our basement that sits on an exterior wall. On the exterior that part of the wall is built out to accommodate the vent and enclosure. On the inside it is very cold and appears to be poorly insulated.

Does anyone know where I can find details of how it should be insulated and with what materials? I would like to use EPS or something but need to know if it should be rated for heat.

I thought it would be easy to find information on how this enclosure should be framed and thus insulated, but I can't find anything. Thanks.

 

[rashomon]

It's been a week and I was hoping someone would have some information. I've attached some photos to show what's going on. I don't know how this is supposed to be done properly. Here are my concerns:

1) In my case there's only fiber batts up to the height of the stove and then it's all uninsulated.
2) I don't know if the plywood box they use to nail the cedar siding onto serves as an air barrier or if I need something additional
3) Do I need to have drywall (or a fireproof plywood/osb) opposite the insulation facing the stove?
4) The rock-wall on the interior that surrounds the insert appears to not have insulation behind it. I attached a photo from the backside where it appears the rocks sit up against the drywall which is against the framing. I don't know how these walls typically attach to the wall and if there should be insulation. The picture of the exterior shows the framed out area for the chimney doesn't even cover the footprint of the rock-wall. Should I assume that entire area is uninsulated and should therefore extend the framed out area to allow for insulation?
5) I simply can't find an easy to understand illustration of what this should look like done properly. Does anyone have something to help?

 

[johneh]

It looks to me that this fireplace was an afterthought.
A hole was cut in the wall fireplace inserted and a bump out built around it.
The bump out should be insulated top to bottom with Rock Wool batting.
The rock wall can be put up in many ways from a thin-set mortar to PL glue
and most likely on a sheet of plywood over the drywall that should be insulated
like normal house insulation. This is assuming the firebox is a zero-clearance unit

 

[rashomon]

Hi johneh. I really appreciate your reply. Yes, I believe you're right. For some reason I just can't find information on how to insulate this situation. For example, you mention Rock Wool. Is this so I don't have to cover the insulation with a fire rated covering? I've read of others using XPS or EPS foam and then a sheet of dry wall.

I'm afraid this rock wall may be the biggest issue. I haven't taken down the exterior plywood yet, but in the photo you can see I got a camera to show how the rocks are attached to something that looks like a cement board attached to plywood attached to flat facing lumber directly to the cedar siding-- no insulation.

Wouldn't it be best to build out the entire footprint of the rock wall so I can fit EPS foam behind it and then address the fireplace bump out? Thanks

 

[rashomon]

I am creating a new thread for this topic because I have better information on what was wrong and also how I should proceed.

I would delete this but can't find a way to do that.

New post is here - https://www.hearth.com/talk/threads/need-quick-advice-re-insulating-exterior-of-old-b-vent.201557/