Insulating exterior basement wall around old brick fireplace

[jailguard811]

Hi guys,
I read many posts on hearth.com for years in anticipation of doing this upgrade. I have an older Fireplace in the basement. I want to install a Century high efficiency wood stove. However, before I install it, I want to insulate the wall it is in. The wall is a below grade exterior CMU (cinder block) wall. I want to install 1" rigid foam on the CMU, then frame it, fill the voids with R-13 for a total of R-18 and finish with drywall on the sides and/or Durarock above the stove. Can this be done safely and by code? If it can, this will extend the wall by 5". What do I need to do to make up this 5" from the old fire box? Picture #1 is what I have. Picture#2 is how I plan to insulate and frame. Picture #3 is what I want it to look like when I am done.

 

[pen]

You'll be fine so long as you do not do the insulation over top of the current brick layer you have, and immediate vicinity around the surround (as per manual). If you just do the basement walls, then you are just fine.

Just follow the clearance to combustibles as listed in your new stoves manual, and you are good to go as far as I can see since you are putting stone over brick in the immediate area of the unit.......then the insulation and framing from there?

 

[BruceNorEast]

Welcome JailGuard811,

This is my first burning season, so I've only got a few things to help until others can weigh in.

My guess is you should start with these: First, check with your town hall to see if a permit is required and if so talk with the building inspector to find out what code requires and what he will want to see. Next call your homeowners insurance and see if they are ok with your plans.

Are you planning on using an insulated liner? I think this will be required if chimney clearance to combustibles is not met. For example, I have a outside chimney and there is a one inch air gap between the chimney and the sheathing for the inside wall.

If you are planning on putting the finish stone ontop of the insulated wall you plan to add, then you'll need to be mindful of the clearance requirements to the studs in that wall, etc. I don't think you can put studs against the brick unless you install a liner that is listed for zero clearance. Others can help clarify that.

Good luck to you!

 

[jailguard811]

You'll be fine so long as you do not do the insulation over top of the current brick layer you have, and immediate vicinity around the surround (as per manual). If you just do the basement walls, then you are just fine.

Just follow the clearance to combustibles as listed in your new stoves manual, and you are good to go as far as I can see since you are putting stone over brick in the immediate area of the unit.......then the insulation and framing from there?

 

[jailguard811]

Ok, I'm not sure which "brick" your referring to. i assume you mean the regular red brick above the fireplace. Secondly, If I insulate that wall by the time I have the drywall on, it will protrude 5" past the current fireplace. So the wood stove will be recessed. .......not good. Can I mortar an additional fire brick row along the outside edge where the current firebrick ends?

 

[begreen]

Assuming that you are putting in a liner and thimble, you an insulate and frame to within 12" of the new thimble. Or install an Insul-Flue or Safe-T-Thimble for the pass-thru. Be sure to get the chimney cleaned before installing the stainless steel. liner.

https://www.hearth.com/econtent/index.php/articles/passing_a_chimney

 

[bholler]

If you are installing a freestanding stove you just need to honor all of the clearance requirements of that stove the fire box doesn't really matter unless you are doing an insert. So check the clearances of the stove you are going to be using

 

[jailguard811]

OK guys I guess I left a little information out. Masonry fireplace located in basement, masonry chimney, straight shot up. I was planning on using a flexible stainless steel liner from Northern Tool ( picture at bottom). The Century high efficiency 75,000 BTU stove INSERT. Please see links. I'm just a good diy'er. Not a wood stove guru. Guide me please. Links to products below:

http://www.northerntool.com/shop/tools/product_200485050_200485050

http://www.northerntool.com/shop/tools/product_200577754_200577754

 

[begreen]

Ah, the original post said wood stove. An insert is a different case entirely. In this case one needs to pay attention to mantel clearances too. If the plan is to cover the cement block with stone, then I'd leave off the insulation for that section and just mortar the stone to the block.

Be sure to have that fireplace and flue are cleaned and inspected by a certified sweep or mason first.

 

[bholler]

yes like begreen said an insert is a totally different animal. The fireplace needs to be built to code like it was going to be used as a fireplace then mantle clearance required by the insert needs to be met here is a link for proper fireplace construction
http://www.rumford.com/code/clearances.html