Covering exposed rigid foam insulation on foundation
ekheerdt
| Posted in Green Building Techniques on
I am building a new house and plan to have 4 inches of ridged foam on the outside from the foundation to the eaves. My question is how to cover the portion that is above grade level, but below the siding?
GBA Detail Library
A collection of one thousand construction details organized by climate and house part
Search and download construction details
Replies
Eric, Recommend pre-painted aluminum angle flashing. The top (horizontal) face of the 90 degree angle should be at least 5" wide to extend completely over the 4" of foam, and over the foundation wall (under the sill). This then has your flashing performing double duty: protecting the foam from UV rays of the sun, and serving as a termite shield for any termites that bore up from the ground through the foam. Use your backfill soil to hold the bottom of the flashing in place.
You could metal-flash to the bottom of the insulation or if all you need is 8", you could use Energy Edge forms, http://www.certainteed.com/Products/340523.
In addition, This house will be built in southern Iowa and will have a full basement
Eric,
I am considering using one of these coatings from Styro industries (http://styro.net/FoundationandICFCoatings.html) when I do a retrofit on a small house I own.
Do you have termites in southern Iowa? If so, the recent termite discussion might be useful to you.
Lucy
Eric,
The following article contains a list of 11 different materials that can be used to protect the above-grade portion of rigid foam insulation installed on the exterior of a basement wall:
How to Insulate a Basement Wall
Is there a height limitation in usa codes for house finish vs grade level ??
Is there a recommended amount to extend the protection below grade to protect from insects?
Jin,
Q. "Is there a height limitation in USA codes for house finish vs grade level?"
A. According to the 2009 IRC, section R404.1.6, "Height above finished grade. Concrete and masonry foundation walls shall extend above the finished grade adjacent to the foundation at all points a minimum of 4 inches (102 mm) where masonry veneer is used and a minimum of 6 inches (152 mm) elsewhere."
Because of the potential of rot due to splashback, I think it's a good practice to have the lowest wooden components of a building at least 8 inches above grade. Twelve inches is even better.
Aaron,
Q. "Is there a recommended amount to extend the protection below grade to protect from insects?"
A. Insects are capable of squeezing through very small cracks and seams. I don't think there is any way to guarantee that a below-grade layer of material will keep out insects. The insects will be behind the barrier and inside your house before you ever notice. The only way you can be sure insects won't enter is to have some type of inspection area that you can check regularly.