Glossary
Crawl Space Glossary
Encapsulation, vapor barrier, joist, sill plate, sistering, dew point and more: the words crawl space crews use, explained in plain English. Search or scroll.
- Air sealing
- Closing gaps and cracks so air cannot move through them.
- Beam
- A large horizontal timber that carries the floor joists.
- Condensation
- Water that forms when warm, humid air touches a cooler surface.
- Crawl space
- The shallow space between the ground and the first floor of a house.
- Dehumidifier
- A machine that pulls moisture out of the air and drains it away.
- Dew point
- The temperature at which the air can no longer hold its water and condensation forms.
- Efflorescence
- A white, powdery deposit left on masonry as water evaporates.
- Encapsulation
- Sealing the floor, walls and vents of a crawl space with a vapor barrier.
- French drain
- A buried perforated pipe in gravel that carries water away.
- Girder
- The main beam under a floor, usually running the length of the house.
- Jack post
- An adjustable steel column that supports a beam or a sagging floor.
- Joist
- One of the parallel boards that carry the subfloor.
- Mil
- A thousandth of an inch, used to describe the thickness of plastic sheeting.
- Pier
- A column of block or concrete that supports a beam from the ground.
- R-value
- A measure of how well insulation resists heat flow. Higher numbers insulate better.
- Relative humidity
- How much water the air holds compared with the most it could hold, shown as a percent.
- Rim joist
- The board that runs around the edge of the floor frame on top of the foundation.
- Sill plate
- The wood laid on top of the foundation wall that the floor frame sits on.
- Sistering
- Fastening a new board beside a weak joist to restore its strength.
- Subfloor
- The layer of plywood or boards laid across the joists.
- Sump pump
- A pump in a basin that moves collected water out of a space.
- Termination bar
- A metal strip that holds the edge of a liner against a wall.
- Vapor barrier
- A sheet that blocks moisture from the ground from rising into the air.
- Vent
- An opening in a foundation wall meant to let outside air into a crawl space.
- Wicking
- Moisture moving upward through porous material such as block or concrete.
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