Hello,
We are starting to plan a house in south eastern North Carolina about 10 miles from the coast. We are wondering about the best way to seal/not seal the crawlspace. The house will be brick with a metal roof over a raised crawl space. Is it better to vent the crawl space as many of the older homes in that area or should we have a ventless crawl space with a vapor barrier across the dirt and up the foundation walls? Any ideas or recommendations would be welcome. Thanks
vectormaniac
Replies
Go with the second option done well. Go to http://www.buildingscience.com to see abit more about this method.
Go to the Taunton bookstore & get Joe Listbrks Building in a Cooling Climate ( or which ever one suits your climate).
Joe H
You need a vapor barrier either way although you may not want to extend it all the way up the walls to your mudsil as it might channel moisture up into your house's framing and cause rot. Plus, you may want to think about a 1" "inspection gap" to check for termites.
If you decided to go with an "unvented" or "sealed" crawl space, check with your local inspections dept to find out about exactly what they require to satisfy their requirements since, although allowed by NC code, it is a bit of an unusual method. Actually the crawl isn't unvented, but vented to the interior of the house; air still has to be circulated through the area, and it needs to be heated and cooled.
BTW - If you make the crawl space floor grade slightly higher than the exterior grade, then you will have very little chance of a water problem. This would be especially important since I'm guessing the possibility of a water problem in your area is very real... I'm from central NC but know a bit about your area.
Don't think you are going to save a bunch of money by not insulating your floor - that will easily be eaten up by sealing the floor and walls. The cost of doing it right may surprise you. There was an article in JLC (a trade magazine) about 4 years ago by a contractor who does crawl space sealing and lives in eastern NC. You may want to try and get a hold of the article and maybe even contact the author. Try http://www.jlconlein.com
As long as you mentioned a brick house, review with your builder or masonry contractor as to how the flashing at the bottom of the veneer (top of foundation) will be taken care of. A lot of bricklayers don't take this detail seriously, but it can definitely contribute to a damp foundation and crawlspace and is nearly impossible to correct after the fact. A simple but somewhat uncommon thing that can be done to help immensely with this is to start the brick veneer one course below the top of the foundation. I believe that the Brick Industry Association website (bia.org) as a number of detail drawings that show proper flashing etc. Also a proper drainage plane must be put in place behind the veneer.
BTW - this whole sealed crawlspace thing is an FAQ so use the search function here at BT.
It's spelled Lstiburek, and his book is available both at Taunton's site and at buildingscience.com. Well-sealed vapor barrier, no vents, good exterior drainage, and dehumidification. Don't run the vb all the way up the wall, you need to be able to inspect for termite tunnels.