Crawlspaces
Crawlspace Encapsulation on the Westside: Dealing With Damp, Musty Air
Why Westside crawlspaces near the coast get damp and musty, what encapsulation actually involves, and when a simple vapor barrier is enough.
Short answer: many Westside homes near the coast have crawlspaces that stay damp from the ground and from humid ocean air coming through the vents. Encapsulation seals the dirt floor and walls with a heavy liner and manages the air in the crawlspace, which cuts musty smells, protects the wood framing and makes the floors above more comfortable. Sometimes a good vapor barrier is all you need, and we'll tell you if that's the case.
Why Westside crawlspaces get damp
- The ground: bare dirt releases moisture into the crawlspace all year.
- Coastal air: marine-layer mornings bring cool, humid air in through foundation vents, and that moisture can condense on cooler surfaces like pipes and framing.
- Drainage: gutters, downspouts and grading that send water toward the house make it worse.
Signs your crawlspace has a moisture problem
- A musty smell in the house, especially in the morning
- Cold or slightly soft floors
- Damp or stained wood, rust on pipes and hardware, or visible mold
- Old insulation sagging or falling down from between the floor joists
- Rodent droppings or nesting
What encapsulation involves
- Inspection: we check for water intrusion, damaged wood, old insulation and rodent activity, and photograph it.
- Cleanout: we remove debris, failed insulation and anything rodents left behind.
- Seal the gaps: we close rodent entry points and gaps into the house.
- Liner: we lay a heavy vapor barrier over the floor and run it up the foundation walls, taping every seam and wrapping the piers.
- Air management: a fully sealed crawlspace needs its air managed, usually with a dehumidifier or a small supply of conditioned air. Vents are only closed when the design and local code allow it.
When a vapor barrier alone is enough
If the crawlspace is dry, drains well and just has bare dirt, a properly installed vapor barrier over the floor can solve most of the moisture coming from the ground, at a lower cost. We'll recommend the simpler option when it does the job.
Pair it with
- Rodent exclusion, if there's activity under the house
- Closed-cell spray foam on rim joists, to stop drafts at the edge of the floor (spray foam)
- New underfloor insulation where the old batts have fallen
Common questions
What's the difference between a vapor barrier and encapsulation?
A vapor barrier is a plastic sheet laid over the dirt floor. Encapsulation goes further: a heavier liner over the floor and up the walls, seams and piers taped, and the crawlspace's air managed so moisture doesn't build up.
Do I need a dehumidifier in an encapsulated crawlspace?
When a crawlspace is fully sealed, the air in it has to be managed, usually with a dehumidifier or a small supply of conditioned air from the house. We'll recommend the option that fits your home and code.
Will encapsulation help with rodents?
It helps. Sealing the crawlspace closes many of the gaps rodents use, and we pair it with rodent exclusion when there's activity.