Basement questions, answered
Why is my basement damp?
Common causes include rain and snowmelt running toward the foundation, groundwater pressure, plumbing leaks and condensation on cool walls. Taping plastic to the wall for a couple of days helps tell whether moisture is coming through the concrete or condensing from indoor air.
Do I need a sump pump?
If groundwater regularly enters your basement or crawlspace, your home has drain tile without a pump, or the water table is high, a sump pump can keep the space dry. A contractor can evaluate whether outside drainage improvements, a sump system, or both are needed.
How often should I test my sump pump?
Several times a year, and before the rainy or snowmelt season. Pour water into the pit until the pump starts, and check that water discharges away from the house. Replace backup batteries on schedule.
Can I finish a basement that sometimes gets wet?
Fix the water problem first. Finishing over a wet basement traps moisture behind walls and floors and leads to mold and damaged materials.
Do basement bedrooms need egress windows?
Building codes generally require an emergency escape opening, such as an egress window, in basement bedrooms. Size, sill height and window well requirements apply. Check with your contractor and local building department.
What is crawlspace encapsulation?
Encapsulation covers the crawlspace soil and walls with a heavy vapor barrier, seals the space, and controls humidity, often with a dehumidifier. Whether to seal or vent a crawlspace depends on climate and local code.
Should I test for radon?
Yes. The EPA recommends testing homes for radon, which can enter through foundations. Testing is especially worthwhile before finishing a basement. Mitigation systems can reduce high levels.
Is interior or exterior waterproofing better?
Exterior waterproofing stops water at the outside of the wall but requires excavation. Interior drainage systems manage water that enters and send it to a sump pump, with less disruption. The best choice depends on the cause and the site.
What humidity should a basement be?
Many guidelines suggest keeping relative humidity below about 50 to 60 percent to prevent mold. A hygrometer measures it, and a dehumidifier can keep it in range.
Do I need permits to finish a basement?
Usually. Finishing typically involves building, electrical, plumbing and mechanical work that requires permits and inspections.
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