basement floor XPS foam

Users who are viewing this thread

lmei007

Member
Messages
183
Reaction score
0
Points
16
Location
Maryland
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.
 

Cacher_Chick

Test, Don't Guess!
Messages
5,458
Reaction score
213
Points
63
Location
Land of Cheese
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.
 

grahamW

Member
Messages
34
Reaction score
0
Points
6
Location
Ontario, Canada
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.
 

Dlarrivee

New Member
Messages
1,150
Reaction score
0
Points
0
Location
Canada
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.

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.
 

lmei007

Member
Messages
183
Reaction score
0
Points
16
Location
Maryland
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).

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.
 

lmei007

Member
Messages
183
Reaction score
0
Points
16
Location
Maryland
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.

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.
 

lmei007

Member
Messages
183
Reaction score
0
Points
16
Location
Maryland
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

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
 
Last edited by a moderator:

LLigetfa

DIYer, not in the trades
Messages
7,493
Reaction score
574
Points
113
Location
NW Ontario, Canada
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.
 

Dlarrivee

New Member
Messages
1,150
Reaction score
0
Points
0
Location
Canada
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.
 

Dlarrivee

New Member
Messages
1,150
Reaction score
0
Points
0
Location
Canada
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.
 

LLigetfa

DIYer, not in the trades
Messages
7,493
Reaction score
574
Points
113
Location
NW Ontario, Canada
Well.. if you think the Barricade® system you linked to supports your arguement, it falls way short. They claim 1% heat loss through the floor. Their product does not laminate two inches of XPS, not even one inch.

http://www.ovrx.com/subfloor-comparison.html

Don't get me started on engineers and marketeers. Maybe you could design something and then get Vince to pitch it for you. I hear he lost a lot of business after the hooker bit his lip.
vince_shlomi_mug_shot.jpg
 

Dana

In the trades
Messages
7,889
Reaction score
509
Points
113
Location
01609
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.

Since you're not spanning 16" o.c. joists, there's no rationale for going with 23/32" plywood subfloor- XPS hard-sandwiched between even half-inch t&g sheathing for the sub-floor and a concrete slab has PLENTY of structural strength, and flexes far less than 23/32" plywood spanning joists. You don't want to go thinner than 7/16" though (for fastener retention reasons.)

There's an economic rationale for R5 (1") XPS on space heating savings (as well as a comfort rationale) in a MA climate zone & subsoil temp. There's a long term economic rationale for R7.5 (1.5"), but R10 only makes economic sense if

A: It's a DIY and you discount you fully discount the value of your labor

B: You use reclaimed XPS at 25-30% of virgin-stock costs

C: You are stuck only with very high space heating fuel options (propane, or oil, or >12 cent electricity & no heat pumps)

D: You are installing radiant floor to heat the place (in which case R12-R15 might even make sense.)

If you stagger the seams of the subflooring with that of the foam by at least a foot or so for least mechanical creepage you can just float the floor, using foam board construction adhesive between the foam & subfloor. If there's any detectable flex to it you can throw in a few tapcons through-screwed to the floor per panel of subfloor.
 

Dana

In the trades
Messages
7,889
Reaction score
509
Points
113
Location
01609
PFFT! We are talking about a basement below grade were the temps are nothing like a room over the garage. Try some
ROLAIDS®.

Take it from some people who actually do the math:


http://www.buildingscience.com/documents/reports/rr-1005-building-america-high-r-value-high-performance-residential-buildings-all-climate-zones


MA is US zone 5. (See the R recommendations in Table 2, p10, but read the first chapter to understand the rationale.)

See also: http://www.buildingscience.com/documents/reports/rr-1003-building-america-high-r-foundations-case-study-analysis

There's more to it than simply blocking ground moisture or heating season utility savings (but those all count too.) Putting real R-value between the subfloor and slab further reduces the mold & rot potential of the subfloor by increasing it's summertime temp to above the summertime dew point of the ventilation air. At MA outdoor summertime dew points R3 would be the minimum in central MA to mitigate summertime moisture accumulation and mold on the subfloor under a padded carpet finish floor (or area-rug over wood flooring), and the labor cost of putting down 1" or 1.5" is the same as for putting down 1/2-3/4". Without the under-floor R the mechanical dehumidification requirements to protect against mold are much higher than they would be otherwise.
 

Nukeman

Nuclear Engineer
Messages
707
Reaction score
1
Points
18
Location
VA
One thing to remember is that you will probably have to do something with the basement stairs (probably for any of these options). Your last step will be too short, otherwise. Doors can also be an issue with the increased floor height.
 
Top
Hey, wait a minute.

This is awkward, but...

It looks like you're using an ad blocker. We get it, but (1) terrylove.com can't live without ads, and (2) ad blockers can cause issues with videos and comments. If you'd like to support the site, please allow ads.

If any particular ad is your REASON for blocking ads, please let us know. We might be able to do something about it. Thanks.
I've Disabled AdBlock    No Thanks