Crawl Space Waterproofing in Lancaster, PA

Crawl space waterproofing stops liquid water and ground moisture from collecting under your house. It is for homeowners in Lancaster who see puddles, smell mustiness, or find damp insulation and soft floors above a crawl space. The work usually combines drainage, a sump pump and a sealed ground barrier, depending on where the water comes from.

What crawl space waterproofing is and how it works

Crawl space waterproofing keeps liquid water and standing moisture out of the low space under your floor. It usually combines three parts: drainage to move water away, a sump to pump out what collects, and a vapor barrier or full encapsulation to stop moisture rising from the soil. Not every crawl space needs all three.

This page covers the crawl space only. For the wider job of keeping a lower level dry, see our basement waterproofing service. A crawl space behaves differently: it is low, usually unfinished, and a dehumidifier alone cannot dry it out if water keeps coming in.

Signs your crawl space has a water or moisture problem

Most owners never go down there until something upstairs points them to it. A flashlight look after a long rain is worth the effort.

Standing or pooling water

Puddles on the soil, a tide line on the foundation wall, or wet insulation that has fallen to the ground all mean water is entering as liquid. Check the corners and low spots first, and look for mud trails running from vents or wall cracks.

Damp air and a musty smell

A musty smell in the house, condensation on ductwork or pipes, and rusted fasteners point to vapor moving up from the soil. The air can feel heavy even when the ground looks dry.

Damage you can see from above

Cupped or soft floorboards, sagging insulation, mold spotting on joists and sill plates, and doors that stick in humid months are common. Wood that stays damp long enough starts to rot, so soft joists are a reason to act sooner.

Where crawl space water comes from

Water reaches a crawl space three ways: surface runoff, groundwater and humidity. Each needs a different fix, so the cause decides the method.

• Surface runoff: roof water and sloping ground sending water toward the foundation, often from short downspouts or soil that has settled against the wall.
• Groundwater: a high water table or saturated soil pushes water up through the floor or in through the wall.
• Humidity: bare soil gives off moisture, and warm summer air condenses on cool surfaces under the floor.

Drainage and sump options for a wet crawl space

When liquid water is the problem, drainage comes first. A vapor barrier laid over a puddle only hides it.

Interior perimeter drain

A trench is cut along the inside edge of the footing and a perforated pipe is set in washed stone, sloped toward a low point. Water entering at the wall or floor joint drops into the pipe instead of spreading across the soil. The trench is covered and the barrier is tied in over it.

Sump basin and pump

The pipe runs to a sump basin set below floor level. A pump lifts the water out through a discharge line to a spot well away from the house. In an encapsulated space the basin needs a sealed lid, and the line needs a check valve so water does not run back. If you are adding one, read about sump pump installation.

Exterior fixes that reduce the load

Extending downspouts, regrading soil so it falls away from the wall, and clearing clogged gutters cut the water that reaches the foundation. These fixes are often simple, and they belong in the plan before anything is installed below.

Vapor barrier or full encapsulation

Both cover the ground with heavy polyethylene sheeting. The difference is how far the sheeting goes.

Ground vapor barrier

Sheeting is laid over the soil with seams overlapped and taped, then fastened to piers and the wall. It cuts moisture rising from the ground and suits a crawl space that is damp but never holds standing water. It does less if the walls are wet or the vents let in humid air.

Full encapsulation

The sheeting runs up the foundation walls and is sealed at the top, seams and penetrations are taped, and the vents are closed off. A dehumidifier or a supply of conditioned air then controls humidity. Encapsulation only works once liquid water is handled by drainage, and venting rules and any gas appliance in the space should be checked first.

How a crawl space waterproofing visit goes, step by step

A visit starts with a look at your space, not a standard package.

• We check the soil, walls, piers, insulation, vents and any existing sump, and note where water enters.
• We walk the outside: gutters, downspouts, grade and nearby low spots.
• We explain what we found and which of drainage, sump, barrier or encapsulation it calls for, in that order.
• Work goes in sequence: clear and level the floor, install drainage and a sump if needed, then lay and seal the barrier.

Related problems: wall cracks, wet insulation and upkeep

Water often enters a crawl space through cracks in block or mortar joints. Sealing the crack matters, but a hairline crack and an active leak are different jobs, so see foundation crack repair if that is what you found.

After the work, check the sump pump after heavy rain, keep the discharge line clear and keep gutters clean. Look under the house twice a year and replace torn sheeting rather than patching around it. Insulation that has been wet should come out, because it holds moisture against the subfloor.