Building Homes or Extensions/Insulation under cement


Should I put insulation under basement cement floor in a new home construction?

Bob, you didn't share with me where you are.  Perimeter insulation of the vertical wall surfaces, especially at frost depth elevations gives lots of bang for the bucks.  Rigid foam under slab yields less return.  Cold winter ground temperatures would not typically have an effect at basement depths unless you live in the Tundra.  Stopping sub freezing temperature transmission through the basement walls is VERY real and should be addressed.

The money is better spent, IMO, on a 6" gravel capillary break and heavy Perminator type under slab vapor barrier.  If there is any chance of water table issues spend whatever to insure drainage.  There is nothing worse than a basement you can't use due to water problems.

I found a site that I reference often on building envelope questions.  The science is good and the advice is first class.  You may want to visit many issues on their website.

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Dan Griffin


I can answer almost all questions related to the total construction process. My expertise is in commercial construction, though I can field most any residential question. I have hands on experience in concrete, heavy equipment, masonry, all phases of carpentry, interior finishes, and I am fairly strong in mechanical and electrical.


I have over 20 years experience as a commercial carpenter and commercial construction superintendent. I have another 20 years experience in facility management for a major school district.

My favorite hobby for he past 12 years has been singing bass in a The OkChorale men's barbershop chorus and the Mature Moments quartet.

I hold a Bachelor's degree in English and Math. I have completed many continuing education hours in the building trades. I hold a Master Carpenter card from the AGC, Associated General Contractors.

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