DIY Home Improvement Forum banner

1 - 7 of 7 Posts

·
Registered
Joined
·
2,316 Posts
Discussion Starter #1
i live in washington, dc (moderate climate).

someone told me that applying elaborate insulation may be an overkill but that i should still spread some nylon coverings right underneath concrete.

any advice ?

thanks,

- a
 

·
Agent 000
Joined
·
334 Posts
There ain't nothing elaborate about high heating bills. And DC DOES get cold in the winter. Is this a new concrete pour? If so I'd be putting 2" of Styrofoam under it.

  • Gravel
  • 6 mil poly vapor barrier
  • Styrofoam
  • re-mesh or rebar
  • concrete
In that order.
 

·
Registered
Joined
·
2,316 Posts
Discussion Starter #3
thanks. could you tell me exactly which type of vapor barrier and styrofoam to use as i don't get much help at home depot ?

thanks.

- a
 

·
Registered
Joined
·
11,194 Posts
In NYwhen I insulated my crawl space I used 2" polyisocyanurate foam board. I called the manufacturer and they said to use a vapor barrier(6 mil plastic) on both sides of the board. This was a foil faced board. I also used it to line the interior poured concrete walls. The space stays about 10 degrees warmer then the outside temperatures in winter.
Secret Squirrel, any reason for the styrofoam board over the other alternatives?
Ron
 

·
Registered
Joined
·
1,861 Posts
I insulated my basement real tight... still find it very cold late at night in a hot summer day.... couldn't sleep there...it is interesting... upstair is too hot... basement is too cold.... winter may be better as it has heat....
 

·
Agent 000
Joined
·
334 Posts
Secret Squirrel, any reason for the styrofoam board over the other alternatives?
Ron
Nothing other than the product is made specific to this application, good compression strength, code compliant, good R value, is moisture resistant, and readily available. It is usually the product of choice when installing in-slab radiant heat.

See: http://www.dow.com/styrofoam/na/res-us/projects/insulating_under_slab.htm

Addendum: Ron, I think one of the other factors that limited my choice to styrofoam was the Polyiso was never suggested as an underslab product up on the Dow web site. This doesn't necessarily imply that it (Polyiso) is not suitable for that specific purpose. Dow only offers it in thicknesses up to 1".

See: http://www.dow.com/styrofoam/na/res-us/products/tuff_r.htm
 

·
Agent 000
Joined
·
334 Posts
I insulated my basement real tight... still find it very cold late at night in a hot summer day.... couldn't sleep there...it is interesting... upstair is too hot... basement is too cold.... winter may be better as it has heat....
Cold air settles and hot air rises. I have the same problem in my split level... cold at the underground level but swampy upstairs.
 
1 - 7 of 7 Posts
Top