Moisture can be a concern with a crawl space or a basement. Let's look at some steps to prevent the formation of moisture.
Crawl Space
A crawl space is susceptible to moisture and deterioration problems because of the contact with the earth. It will remain drier if you follow these precautions:
- Depth - Allow for a minimum of 12" clearance under beams and 18" under floor joists. A larger crawl space allows for greater air circulation and is easier to service and repair.
- Vapor Barrier - At the time of construction, lay down a 6 mil black visquene (plastic) over the entire soil area. Overlap all the seams on the visquene by 12 inches and tape them closed. Seal the visquene six inches up the crawl space walls.
- Storage - Using a crawl space for storage significantly reduces the needed air circulation as well as creates conditions conducive for rodent and pest infestation. If you have a crawl space height of 5 feet or greater, it could be fitted with vented storage shelves.
- Venting - Most building codes call for screened crawl spaces with 1 ½ square feet of venting for every 25 linear feet of exterior crawl space wall. This aids in the air circulation within the crawl space.
- Drainage - Design all drainage to route away from the house. The yard should slope away from the house for at least 5 feet at a minimum 5 percent grade. Divert all water from roofs and gutters well away from the house. Don't allow roof drainage to saturate the soil around the foundation.
- Sealing - Seal the exterior of the foundation with synthetic rubber or liquid asphalt that has rubber additives.
Basements
The following are some basic precautions you can follow to help your basement remain dry:
- Floor Drains - Install floor drains at the time of construction and keep them in good repair.
- Untreated Wood Materials - Keep all untreated wood materials away from contact with the earth.
- Drainage - Design all drainage to route away from the house. The yard should slope away from the house for at least 5 feet at a minimum 5 percent grade. Divert all water from roofs and gutters well away from the house. Don't allow roof drainage to saturate the soil around the foundation.
- Damp-Proof - Damp-proof all portions of the foundation below the surface of the ground to prevent the wall from absorbing ground moisture.
- Cracks - Seal any cracks in the floors and walls.
- Sump Pumps - While gravity drainage is preferable, when it is not sufficient install a sump pump, checking it twice per year to insure it is operating properly.
- Sealing - Seal the exterior of the foundation with synthetic rubber or liquid asphalt that has rubber additives. Paint the interior walls with a moisture sealant.
As with so many elements of designing and building your dream home, taking the time to build in the proper precautions and safeguards can prevent ongoing problems with moisture or water in your foundation.
