[ILoveBacon]

Hi guys!

Here's some pictures of the area in question: :glasses:

Bare concrete
After cutting the foamboard (not glued in yet)​

Basement information:

-I live in a 1976 made home, located in Calgary (Canada), winter here gets as cold as -30C but the climate is rather dry year round. Very low humidity.
Poured concrete foundation basement that’s had drywall in it since we moved in.

-15 years ago, we had installers put carpet in the basement.
This basement has been used as an extra TV/game room and partial storage room ever since.

-However, there is one area in the basement where there is no drywall. This is a small 5ft wide x 2ft deep section located underneath where the main floor fireplace is, just above.​

Information pertaining to the bare concrete spot in question:

-Historically, we’ve always just stored boxes in this small space. There have been no water problems, and no signs of water damage on any of the boxes that have been here for the past decade.

-HOWEVER, this year, after I removed the Christmas decoration boxes from this area, I realized how COLD the air was in that spot.

-Without the boxes, it feels like it really just sucks the heat out of the entire basements air.

-The carpet is installed in this small area too.

-This has got to be hurting my heating bill.​

So I’ve decided that I want to insulate this area to make my basement warmer:
I’m thinking…

-Install 2.5” thick (2'x8'), rigid blue foam board – Adhere it to the bare concrete walls with the appropriate caulking gun glue.

-Apply spray foam in lines along the bottom and top of the rigid foam boards, AND down the 2 wall corners, to make them seal “air tight”.
​

Questions:

1 - Does my plan make sense?

2 - Is it okay to install this foam board overtop of the carpet?
The carpet is stuck to the floor, and I am worried that if I rip it up there, the rest of the carpet may lose its "stretch".

3 - Should I insulate the concrete ceiling here? Remember, it’s under the fireplace. Should I leave it bare? It's not exactly an outside wall.

4 - All this area is used for is boxes... Should I bother putting anything over the foam board? Installing a 2x4 stud wall feels like it would eat a lot of space.

5 - Anything else I missed?​

Thank you for your time! :vs_karate:

 

[Windows on Wash]

1. Yes.
2. Not ideal and I would leave a small gap at the bottom but it is probably okay.
3. Is the fireplace in use?
4. Yes. Better safe than sorry.
5. Looks good so far to me.

 

[ILoveBacon]

1. Yes.
2. Not ideal and I would leave a small gap at the bottom but it is probably okay.
3. Is the fireplace in use?
4. Yes. Better safe than sorry.
5. Looks good so far to me.

Thanks for the response!

Here's what I've done since then:

Pictures
I ended up cutting out the carpet at the bottom where the blue foam goes.

I then glued to bluefoam to the concrete walls with PL-300 and had it cure for 24 hours with weight leaning against all the boards (leaning tables and such).

After that I filled any cracks I could see with expanding foam.

Next, I will purchase tuck-tape for where the panels join.
​

To answer your question:
2) The fireplace has not been used for many years, but someday we will look to using it again.

My new question is:
What are the risks if I do not cover the foam board with drywall?
It's really tempting just to fill that area with boxes again.
The idea of building a wooden studwall and renting a truck to get the drywall sounds like quite the buzz kill.

 

[joecaption]

What's the warnings say right on the foam insulation?
Foam board should never be left exposed!
It needs to be cover with sheetrock.

 

[Windows on Wash]

Flame and smoke spread are the concerns. I would not take a chance with leaving exposed. It requires a code approved thermal barrier in this case.

 

[ILoveBacon]

After Googling some more, it looks the only risk is that if a fire ever came into contact with the foam board, the fumes would be more dangerous than even the fire smoke.
I'm not especially worried about fire, but true enough, it's better to be safe than sorry.


Okay, so to finish that area with 1/2" drywall, what would be the simplest way to get that done?
Just build a frame (out of 2x2's) around those inside walls and screw on drywall at all 4 corners?

Thanks again.
I apologize if I seem impatient

 

[joecaption]

No way do you want to use 2 X 2's!
Glue up the 2" foam, and build a 2 X 4 wall in front of it with a pressure treated bottom plate.

 

[Gary in WA]

2x2's would be pretty easy, IMO. Add one fastener through the fb into concrete at mid-height. As you don't mention future wiring/plumbing here, anyhow... be sure the fireplace damper is closed --even then- cold air will settle at grate and permeate through to chill the basement at that area, if sealed at hearth. IMO, insulate the concrete floor above with foil-faced XPS if allowed by AHJ. Though not pretty, drywall fasteners through fb into concrete will attach drywall directly to fb- very space-saving. Few pertinent links; cover the fb;http://www.nrc-cnrc.gc.ca/ctu-sc/ctu_sc_n70

no PT required with vb; #3, eg;http://publicecodes.cyberregs.com/icod/irc/2009/icod_irc_2009_3_sec017.htm

Gary