Bump-out Fireplace

I had a bump-out fireplace at home. Winter time, it is horrible...wind is coming from the fireplace into the family room. I have taken down all the siding and ensured that there are insulation behind the plywood, and also used the Great Stuff insulation to fill in whatever gap that I can find, and add additional insulation at the roofing. but the condition only improved a little. This spring/summer, I am considering to take down the plywood and roofing and re-do the whole insulation. Anyone have any experience that I may need to be aware? or is there anyone who have experience on this and have it resolved? Will using the bricks to seal off the base on the bump-out unit help at all?

 

Fireplaces can be notoriously drafty. You can insulate the walls all around the thing and still have a draft. So you might be advised that you could quite possibly tear out your walls, insulated everything as best as you can... put it back together and STILL have a draft.

Additionally, air can come IN the flue just as easily as smoke can go OUT. If you aren't using the fireplace close the damper, that's the best you can do.

If your firebox is not enclosed in brick and mortar, then that's a possibility to pursue with a mason. You didn't mention though if this was a brick chimney, wood framed, ducted through a wood frame, etc. That info might help.

 

I guess the bump out is hanging out there with no foundation under it? Too many times the base/floor of the bump out has no insulation in it. It should be insulated, flashed and sealed to prevent drafts and heat loss. Just a thought.
You could brick it but that would be footers, block, brick, plate, flashing and siding trim work.