A crawl space inspection, however, can only be performed if the crawl space is accessible. In many homes, they are not. These homes were built under the FHA Minimum Property Standards, which allow the ground level to be 18 inches below the bottom of the floor joists and 12 inches below the bottom of the girders. Even with an access opening to the area, the clearance in the crawl space is still too low for a person to be able to conduct a detailed inspection. If the crawlspace is inaccessible, look into the area from the access opening to detect any obvious issues or problem conditions.
The crawl space is usually quite damp, even if there are no problems with water seepage. The dampness is the result of the capillary rise of ground moisture. While with a basement the ground is typically covered with a concrete floor slab, the floor in a crawl space is usually bare earth. The soil might appear dry, but moisture can be present nonetheless. In some soils, the capillary rise is more than 11 feet above the water table.
Dampness cause by capillary moisture can be effectively reduced by covering the ground with a vapor barrier such as polyethylene or roll roofing, though the latter tends to deteriorate from fungi.
Moreover, the crawl space should be ventilated in order to minimize the dampness. There should be at least two vent openings on opposite sides of the foundation, with a total free area of one square foot for each 1,500 square feet of crawl space area, if there is a ground cover. If there is no vapor barrier, at least four vent openings – one on each side – with ten times the total free area should be placed. During your crawl space inspection, look for vent openings. If there are none or they have been permanently blocked, record the condition on your worksheet for future correction.
In addition, remember that crawl spaces are generally not heated, so unless there is some insulation between the floor joists, there will be some heat loss between the heated room above and the unheated crawl space. Moisture from the house can travel downward through the floor, so the insulation should have a vapor barrier on one side in order to reduce moisture entry into the crawl space. Install the vapor barrier above the insulation, facing the heated room, not the crawl space. If you place it below the insulation, the vapor will condense on its surface during cool weather and depending on the amount of vapor, this condensation buildup can reduce the effectiveness of the insulation. Check the insulation for missing, loose or hanging sections which should be re-secured or replaced. Any uninsulated heating ducts or pipes in the crawlspace should be insulated.
If the house you are inspecting has both a basement and a crawl space, the crawl space can be vented to the basement, so there is no need for venting to the outside. Sometimes, there are no signs of water seepage in the basement, but there are indications in the crawl area. The basement can be repainted or redecorated to cover up any signs of a water condition, however the crawl space will have some evidence of the issue.