I have lots of questions about crawlspaces that I want to understand, and need a reference for this topic. Among other things, I wonder about radon possibilites, humidity issues, suggested ways to counteract these problems, ventilation suggestions, etc. I want to use this large area for storage, but foresee trouble.
Thanks for any pointers. Les
you know the short answer is a garage sale :) the long technical answers are at:
When we built our house (2003-2004), we were required to have 1 square foot of perimeter venting for every 150 square feet of the crawlspace, placing vents as close to the corners as possible and providing cross ventilation (so you get air movement through the crawlspace). We added a few extra vents just to be safe.
The ground in the crawlspace also had to be covered with a layer of 6-mil plastic. I installed a 2" layer of pea gravel before laying down the plastic for better drainage and to prevent small sticks or rocks from poking holes in the plastic. It's also a bit easier on the knees when crawling around down there.
The ground outside the house should slope away from the house to direct any surface water (rain) away from the foundation. Make sure gutter downspouts are directed well away from the foundation too.
If you have a high water table, or water is otherwise getting into your crawlspace, you should slope the ground in the crawlspace to a point where you can install a sump pump to pump out the water (away from the house, of course).
The foundation walls should be waterproofed on the outside, and you should have a perimeter "french drain" running around the house to take any water that finds it's way down the foundation wall out away from the house, instead of getting into your crawlspace.
We live in Washington state where we get lots of rain, and our crawlspace is nice and dry.
If you plan on storing anything down there, be sure you protect the plastic vapor barrier so it isn't damaged. Maybe planks set up on blocks or something.
Good luck,
Anthony
Get a headlamp so that you can free your hands.
A headlamp can also keep you from hitting your head on beams.
Don't let your dog follow you in or s/he will find all of the dead animals (and living ones too!)
Climate and local subsurface conditions have some bearing on the approach. Builder's Guide to various climates are available on Building Science Corp web site. They are not well organized and don't have "the final answer" but can be valuable. TB
The ones provided by Bill and Jay are a couple of the best that I've seen.
Simple, home sampling kits are available at Lowes and Home Despot (hehe). You send it off to a lab for the results.
See above oted references.
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