Installing XPS foam in basement

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Posted by: from Vaughan
2/1/2016 at 12:56:53 PM


I am in almost ready to begin finishing my basement. For insulation, I have decided on 2 XPS up against foundation wall, then framed, then r20 batts in between studs (to achieve r30). I am also planning on installing the Barricade insulated floor panels.

My questions are:

- What should get done first? The XPS? If so, when installing do I leave space at the bottom, then fill that space with spray foam? or have the bottom of the board sit flush against concrete floor?

- Does the Barricade subfloor have to be installed first, so the foam boards and framing sit on top? Or Put the foam up and frame, then install the subfloor?

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Matthew from Matt of All Trades in Kitchener
Date/Time2/1/2016 at 6:34:14 PM


For the walls, the foam goes on first, down the floor, "tuck tape" on all seams and the framing goes in next.

If you want to put accoustic sealant - black tar type sealant - between the foam and the floor that will seal everything.

If you are looking to warm up the floor, I suggest skipping the barricade floor and strapping it out with dimensional lumber and filing the cavities with the the same rigid foam.Cover with either plywood or OSB and your choice of finish flooring.

If you are looking to have a "thermal break" between concrete and flooring, delta membrane and 5/8" OSB screwed down. aka, poor mans Dri-Core would do the trick.

Either sub floor method is acceptable, but is dependant on what you are trying to achieve.

As for the order of operations between floor install and wall framing....I prefer to install the walls first with proper gaskets under lumber. I do this so the wall is more secure to the concrete with 3.25" tapcons screws in 1.5" lumber giving 2" of hold....if walls built on top of foam and plywood, that thickness is subtracted from screw depth.

Personal choice really and I don't think either way is more right or wrong than the other.

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Date/Time2/2/2016 at 9:55:26 PM

And Hi to you,

First you glue the XPS to the foundation walls. And just let them sit on the concrete floor. Don't bother using spray foam at the base. Also use Tuck tape on all of your joins with the foam board. Then you frame all of your wall. Be sure to spread out the white foam rolls under every interior and exterior base plate for all your walls. The you can ramset them in Against the foundation and interior walls. I do not use foam backed subfloor panels on my job sites. The minimal difference it makes in insulation is not worth losing the ability to move air and water under your floors to the drain if you have either plumbing leaks or a foundation problem. I always use DriCore 24" subfloor panels. So at this point install all the subfloor regardless which you use. Be sure to have them about 1/2" off the stud plates on the walls.

At this point you are ready to start you electrical and plumbing work. When that is complete its time for drywall.....and then all the rest Enjoy!


James Fram

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Carlisle in Vaughan
Date/Time2/3/2016 at 3:45:23 PM

Thanks! You mentioned not using foam due to sacrificing water and air movement.

What if I used delta FL first, then high compression foam, then osb as a subfloor?

Thoughts? or still minimal insulation improvement over regular dricore?

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Matthew from Matt of All Trades in Kitchener
Date/Time2/3/2016 at 6:27:41 PM

Adding all those materials can really raise the height of the finish floor. If you have the head room sure, but I think the insulation is overkill and not required.

I agree with James that the barricade type floor is no good for the same reasons...really want the air flow.

These walls were spray foamed, but could have this rigid insulation glued to concrete, then framed, then subfloor....

Have fun.

Installing XPS foam in basement

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