Why Is My Crawl Space Wet in Summer?

From spring to fall, canals and ditches carry water across the Treasure Valley, and yards are watered heavily. The City of Caldwell runs a pressurized irrigation system for many neighborhoods. All that water soaks into the soil, and in some spots the water in the ground rises closer to the surface. Crawl spaces sit just below grade, so they are the first place it shows.

A spray head that hits the foundation every morning can soak the soil right against the crawl space wall. Over a summer, that water finds its way inside. Walk the yard while the sprinklers run and turn heads away from the house.

Roof water that empties next to the foundation, and soil that has settled toward the house, both send water under the floor after storms. Extend downspouts several feet away and add soil so the ground slopes away from the walls.

Not all summer water is groundwater. A dripping supply line, a leaking toilet seal or a cracked drain can wet one area under the house. If water appears under one room only, suspect plumbing first.

Standing water under the house raises humidity, soaks insulation, and can lead to mold on joists and rot over time. It also draws insects and can make wood floors cup.

Pumps out standing water, removes wet insulation, dries the joists with dehumidifiers and finds the source. See crawl space water removal for the details.

If water returns every summer, options include a perimeter drain and sump, a heavy vapor barrier and better grading. A foundation or waterproofing contractor usually handles those.

Groundwater and seepage are usually excluded from homeowner policies. A burst pipe under the house is often covered. Check your policy before summer.

Groundwater tends to appear evenly across the low side of the crawl space and rise and fall with the irrigation schedule. A plumbing leak usually wets one area, often under a bathroom, kitchen or the water heater, and does not change with the seasons. If you are not sure, turn off all water use and watch the meter; a moving meter points to a leak.

Take photos, check whether the furnace or ducts are in the crawl space and whether water has reached them, and call. Do not crawl into standing water near wiring. If the water is from a pipe, close the main valve.

If your neighbors' crawl spaces get wet at the same time each summer, groundwater is likely. Sharing what works, such as a sump or better grading, can save everyone money.

A new lawn is watered heavily for its first weeks, and new beds next to the house are often watered daily. If you have just landscaped, check the crawl space more often that first summer and keep sprinkler spray off the foundation.

In crawl spaces that stay humid even without standing water, a dedicated crawl space dehumidifier can hold moisture down. It works best with a sealed vapor barrier and closed vents.

Call when you see standing water, wet insulation or mold on joists, or when a musty smell spreads through the house.

Most homeowner policies exclude groundwater and seepage, so summer crawl space water from irrigation is usually not covered. A burst pipe under the house is a different matter. Fixing drainage is often cheaper than repeated cleanups.

Once a month from May to September, open the crawl space access and look with a flashlight. Check the vapor barrier for standing water, the insulation for sagging and the joists for dark spots. Walk the yard while sprinklers run and look for spray hitting the house. It takes ten minutes and catches most problems early.

If water returns every summer despite better sprinklers and downspouts, a drainage or foundation contractor can install a perimeter drain and sump, or seal the crawl space. Ask for options and costs before deciding.

Summer crawl space water is common in Caldwell, but it is manageable with good sprinklers, downspouts, grading and a regular look below the floor.

Check your crawl space in late spring and mid-summer with a flashlight. Early water is easy to deal with.

Questions about why is my crawl space wet in summer? Call (208) 923-0564 to reach a local Caldwell provider, 24 hours a day.