Crawlspace Water Damage in Mechanicsburg, PA: Standing Water, Sagging Insulation and Damp Joists Under the Floor

A wet crawlspace is a problem you cannot see from inside the house until the floor feels soft, the house smells musty or a pipe fails in January. The space is low, dark and awkward to work in, so water sits there longer than it would anywhere else.

This page covers how water gets under a house, what it does to the floor above and how we dry a crawlspace.

What water does under the floor

Crawlspace water usually comes from one of five places: surface water that runs toward the foundation, groundwater that comes up through the ground, a plumbing line that split, a gutter downspout that dumps next to a foundation wall, or humid air that condenses on cold surfaces. The result is the same. Insulation absorbs water and sags, the plastic vapor barrier (if there is one) collects water on top, joists and subfloor stay damp, and the air under the house gets humid.

Wet insulation is the worst part. It falls or presses against the subfloor and holds water there, so the wood above never dries. Over weeks, that becomes mold on the joists and soft spots in the subfloor.

Why crawlspaces take water around here

From 1991 to 2020 the Middletown-Harrisburg station averaged about 44 inches of precipitation a year in our calculation from NOAA daily data. The Conodoguinet Creek gauge at Hogestown, about 3 miles north of Mechanicsburg, has recorded 86 floods since 1932, with a record crest of 17.01 feet in June 1972. Rain this steady keeps the ground wet, and a crawlspace is the lowest point under the house.

Winter adds a second risk. Supply lines and drain lines run through the crawlspace, and in a typical January the Middletown-Harrisburg low fell to 32 or below on about 25 nights out of 31. A pipe near a foundation vent can split. See frozen and burst pipe cleanup.

Safety first: crawlspaces are tight spaces

• Electricity. Wiring, junction boxes and sump pumps may be in the space. Do not crawl into standing water with anything plugged in.
• Air. Mold, dust and, if you have a gas appliance or furnace nearby, combustion gases can be present. Wear a respirator.
• Space. Sharp nails, low joists and pipes. Wear knee pads and gloves, and tell someone before you go in.
• Animals. Wet crawlspaces attract rodents and insects. Look before you reach.

If you cannot see the floor of the crawlspace, or water is deep, stay out and call.

How we dry a crawlspace

1. Find the source. A leak gets stopped. A drainage problem gets noted for the right contractor.
2. Pump the water. A small submersible pump handles water on the ground or on the barrier.
3. Remove wet insulation. It is cut away and carried out. Insulation that has soaked usually does not recover.
4. Read the wood. Joists, sill plates and subfloor are checked with a moisture meter. Anything that reads high is dried or, if damaged, noted for replacement.
5. Set dehumidifiers and air movers. Air movers in a crawlspace move air across joists, and a dehumidifier pulls the water out of the air. Following the IICRC S500 guidance, we keep drying until the readings match unaffected wood.
6. Clean and check for growth. Surface mold on structural wood is cleaned. Heavy growth may need containment and removal. See mold removal.

What to look for from above

Sign inside the house	What it can mean
Floor feels soft, springy or cold	Wet subfloor or damaged joists
Musty smell that gets worse in summer	Humidity and growth in the crawlspace
Cupped or buckled hardwood	Moisture from below
Doors that stick	Moisture swelling framing, or movement in the floor
Higher heating or cooling bills	Wet or fallen insulation

Older houses, older crawlspaces

Census survey estimates put roughly a third of Mechanicsburg's housing as built before 1940 and about 63 percent before 1970. Older houses can have shallow, irregular or dirt-floor crawlspaces, stone or block foundation walls and plumbing that was added over the years. Those conditions make water harder to keep out and harder to dry.

CDC, EPA and FEMA guidance for flooded homes is to dry everything within 24 to 48 hours if possible, which is hard to do under a house. Call early. Related pages: basement flooding cleanup, structural drying and dehumidification and water damage restoration. We work in Mechanicsburg, Shiremanstown, Camp Hill and Carlisle.

Crawlspace water questions