Crawlspace Flooding in Marysville, WA

Crawlspace flooding is one of the most common rain problems in Marysville because crawlspaces are common in Puget Sound houses and winters are long and wet. When an atmospheric river rains for several days, the soil around a foundation fills up, runoff from the hills toward Ebey Slough and Quilceda Creek moves through yards, and water seeps through foundation walls or enters at low vents. Older homes near downtown and in Sunnyside often have shallow crawlspaces and vent openings close to grade, while homes on lower ground toward the delta sit closer to a high water table. Water under the floor stays out of sight, so it often sits for a week or more before anyone looks.

In the first hour, water pools on top of the vapor barrier or soaks the bare soil and starts wicking into foundation sills. By 24 hours, fiberglass insulation between the joists has absorbed water and starts to sag or fall. By 48 hours, the humidity under the house rises sharply, floors above may start to cup, and mold can begin on joists and the underside of the subfloor. After a week, there is often a musty smell inside the home, wet insulation lies on the ground, and the wood framing needs extended drying or treatment.

Most of the wood structure in a flooded crawlspace can be dried in place. Floor joists, beams, posts and the underside of the subfloor usually dry well with low-grain dehumidifiers and air movers when the vents are closed off and the space is treated like a drying chamber. Foundation walls and sill plates dry along with the framing, and finished floors above often flatten back out once the subfloor dries, especially solid hardwood that was caught early. Ductwork that only got wet on the outside can usually be dried and cleaned rather than replaced.

Some materials in a flooded crawlspace are almost always replaced. A vapor barrier with water on top of it is pulled out, because the plastic traps moisture against the soil and holds silt and debris. Fiberglass batts between the joists that absorbed water lose their value and can hold moisture against the wood for weeks, so they are removed and replaced once the framing is dry. Duct insulation that soaked up water and any stored boxes or wood scraps under the house are also removed. Where flood water came from a creek or street runoff, it is treated as dirty water and the soil surface is cleaned.

Crawlspace flooding calls come from many parts of Marysville. Older homes around downtown and Sunnyside often have shallow crawlspaces, and during the November 15, 2016 downpour most of the city emergency calls came from Sunnyside and central Marysville. Homes on the lower ground near Ebey Slough and Kellogg Marsh sit closer to wet soils, and 1970s and 1980s homes in Marshall and Kruse and in Shoultes often have original vapor barriers and insulation that hold water once it gets in.

Crawlspace flooding is just as common in the towns nearby. In Stanwood, many homes sit on low delta ground behind dikes, and in Arlington, homes near the Stillaguamish valley see crawlspace water during long rains. In Everett, older crawlspace homes in the north end deal with the same seepage. Call any time and one call connects you with a local crew in your town that can pump out the water and start drying under the house.