Drainage problem needs to be addressed before restoring crawl space
Q. I recently discovered about 3 to 4 inches of standing water under my house. I pumped out the water and removed the plastic sheets that covered the ground so the soil can dry out. Once the ground is dry, should I spread lime over the surface to help prevent mold? And should I also reinstall the plastic sheets?
A. Mold prevention is not necessary unless you have moisture on cellulose materials. Wet soil will not support mold growth. Therefore, lime is not needed on the ground surface under your home.
The purpose of the plastic membrane is to prevent ground moisture from evaporating and causing humidity and condensation in the crawl space. If faulty ground drainage causes flooding above the plastic, then the plastic serves no useful purpose and does not need to be replaced.
The primary concern in this case is the drainage problem. To solve this, you should have the property evaluated by a geotechnical engineer (drainage specialist) to determine the water source and the best means of preventing future water intrusion. The engineer might recommend french drains around your home, a sump pump under or around the building, and possibly both. Once this is done, replacement of the plastic membrane may be advisable, but additional foundation vents might also be needed to minimize humidity and condensation.
Q. The exhaust fan in my bathroom ceiling is connected to a metal duct in the attic. This duct terminates next to a screened vent at the eaves. Should this vent duct terminate on the outside of the building, or is it OK to terminate on the inside of the attic vent? What does the building code require?
A. According to the International Residential Code, a bathroom should be vented to the exterior either by an openable window or by means of "a mechanical ventilation system - exhausted directly to the outside." At first glance, one would assume that "exhausted directly to the outside" requires a vent shaft terminating at the exterior of the building. But building codes are interpreted by the agencies that enforce them. And many newly constructed homes have bathroom vent ducts that terminate at screened openings in attics. It would appear, therefore, that some building officials are opting for that interpretation of the code. To determine the specific legal outlook for bathroom ventilation in your area, consult your local building department.
Q. Is it a bad idea to vent an electric clothes dryer into an unfinished basement or crawl space to help keep the floor a little warmer? With fuel costs so high, why waste the warm air from the dryer?
A. This question has been a recurrent issue in this column. To summarize past articles, there are three reasons not to vent a clothes dryer into your basement or crawl space:
• Increased humidity can promote the growth of mold and fungus in your home.
• Dryer lint can accumulate and is regarded as a fire hazard.
• Venting a clothes dryer into a building is a code violation, because of reasons No. 1 and No. 2.
• E-mail questions to Barry Stone at www.housedetective.com or write AMG, 1776 Jami Lee Court, Suite 218, San Luis Obispo, CA 94301.