basement floor XPS foam

My unfinished basement has a 87" ceiling height right now. I don't know I should use 1", 1.5" or 2" XPS foam on the floor? The whole basement floor plan will be 6mil poly + XPS foam + 23/32" T&G plywood + engineered wood floor.

Personal preference, how tall are the people who live there?

One thing to consider is that a standard door rough-in is 82-1/2 tall. Additional height will be required to install a standard casing around the opening.

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Originally Posted by dlarrivee

Personal preference, how tall are the people who live there?

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5'10" for now.

Can I ask the purpose of the poly? If your basement floor is allowing water up from beneath then you're likely going to have issues no matter what you do (IMHO).

I use ship-lapped, rigid foam insulation and use 2" on the walls and 1" on the floor. Glue to the walls & floor with the correcct adhesive and each seam should be tuck-taped, and spray foam used to fill any gaps around the edges. All rigid foam insulation is mould and mildew resistant and won't hold moisture, even if you have a flood in your basement. You can use mould-resistant drywall as well.

The goal of insulating in this manner is creating a thermal break between the air inside your basement and the air outside. It will eliminate any air movement behind the walls that could lead to condensation.

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Originally Posted by grahamW

Can I ask the purpose of the poly? If your basement floor is allowing water up from beneath then you're likely going to have issues no matter what you do (IMHO).

I use ship-lapped, rigid foam insulation and use 2" on the walls and 1" on the floor. Glue to the walls & floor with the correcct adhesive and each seam should be tuck-taped, and spray foam used to fill any gaps around the edges. All rigid foam insulation is mould and mildew resistant and won't hold moisture, even if you have a flood in your basement. You can use mould-resistant drywall as well.

The goal of insulating in this manner is creating a thermal break between the air inside your basement and the air outside. It will eliminate any air movement behind the walls that could lead to condensation.

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Mold only grows on organic materials, concrete, poly, foam, etc. etc. none of them support the growth of mold.

If your basement floods, having gimmicky drywall wont make a difference.

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Originally Posted by grahamW

Can I ask the purpose of the poly? If your basement floor is allowing water up from beneath then you're likely going to have issues no matter what you do (IMHO).

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The poly is to reduce moisture vapor from the ground and to prevent small amount of water from ground if any. But it will be bad if water is from inside (water pipe), I think.

In my case, that poly layer is for moisture only because I have added french drain inside my basement and outside grading has been addressed as well.

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Originally Posted by dlarrivee

Mold only grows on organic materials, concrete, poly, foam, etc. etc. none of them support the growth of mold.

If your basement floods, having gimmicky drywall wont make a difference.

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I plan to attach the drywall at least one inch above from the plywood. That means as long as there is no more than 1" water in my basement, the drywall will be safe. I have floor drain and french drain. I think my basement probably should be good enough.

If you need an interior weeping system, then you probably should have a gap as well. Something like dimpled plastic under the insulation, or skip the insulation and put in DRIcore. Insulation on the floor has little payback.

http://www.dricore.com/en/eIndex.aspx

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Originally Posted by LLigetfa

If you need an interior weeping system, then you probably should have a gap as well. Something like dimpled plastic under the insulation, or skip the insulation and put in DRIcore. Insulation on the floor has little payback.

http://www.dricore.com/en/eIndex.aspx

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We only get water in 100yr's storm and at that time the outside surface water was not handled properly. Normally there is no water issue and the sum pump basin is dry all seasons

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Originally Posted by LLigetfa

Insulation on the floor has little payback.

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I'm really getting fed up with all of the mis-information going on here...

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Originally Posted by dlarrivee

I'm really getting fed up with all of the mis-information going on here...

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PFFT! We are talking about a basement below grade were the temps are nothing like a room over the garage. Try some ROLAIDS®.

If there really was so much payback, you'd think the DRIcore engineers would be all over it and manufacture a version of their product with an inch or two of XPS sandwiched in it. DRIcore has an R value of 1.7 plus the engineered wood that is going on top of that. I don't know the degree days in the state of MA, but for sure less than ours. Summer cooling costs may even factor in.

You need to do some research outside of the Home Depot flyer my friend. The main reason DriCore engineers (you think they actually have engineers?), don't add 2" of XPS is COST...

It is already over priced and uses OSB instead of proper plywood, they wont sell a single 2'x2' tile if they double their price point again.

Oh and p.s., the other reason is because someone else already came out with such a product. Again, over priced.

http://www.ovrx.com/

I think it is hilarious that you figure it takes a team of engineers to glue 2 building materials together and come up with a marketing scheme.

I would use Delta FL and plywood any day of the week over DriCore, and I would use XPS and plywood any day of the week over any xps+osb glue together crap.

For anyone out there listening LLigetfa also recommends MDF baseboards in basements with dampness issues.

I'll have to head over to Home Depot and ask the experts there, then report back on whether or not having a cold floor in a finished basement is a good idea.