Structural drying for Lake Stevens homeswhen dry to the touch is not dry

Structural drying is the controlled removal of moisture from the materials a house is built from: wall studs, floor joists, plywood or oriented strand board subfloor, drywall and the sill plates at the bottom of the walls. Wood and drywall are porous. Once water is on them, it travels into them, and it leaves again only as vapor. So the job has two connected parts: move water out of the material into the air, and then take it out of the air.

Air movers handle the first part by pushing fast, dry air across wet surfaces, which encourages evaporation. Dehumidifiers handle the second by pulling that vapor out of the room. Neither works well alone. Air movers without dehumidification simply raise the humidity in a closed room, and that damp air can then soak back into materials and spread the problem to rooms that were never wet. A dehumidifier with no airflow leaves the surface layer of air saturated, and evaporation stalls.

Heat matters too, because warm air holds more moisture and wet materials give up water faster when they are warm. This is one reason a job in an unheated crawlspace or a closed-up house in January tends to go slower than the same job in a heated room. The person planning the work has to balance these three things, airflow, humidity and temperature, against the particular materials in your home.

Standing water has to go first. Pumps, extractor wands and truck-mounted or portable units take out liquid water far more quickly than any amount of evaporation could. Water removal gets rushed sometimes, but each extra pass of the extractor over a carpet takes out water that the drying equipment no longer has to deal with. Only then does the drying setup make sense.

Drying a house depends on where the moisture goes, and in western Snohomish County the outside air is often already damp. Published 1991-2020 normals from a NOAA station in Everett, about six miles west of Lake Stevens, show about 40 inches of precipitation a year, with about 5.8 inches in November, and about 5 inches each in December and January. Only July and August drop near an inch. Modelled Open-Meteo figures for the Lake Stevens location read much higher, around 71 inches a year long term, and may overstate things, so we label them as modelled. ^[5]

What this means in practice is that opening the windows does not always help. In summer, ventilation can work well. In a rainy November, outdoor air can carry more moisture than the indoor air you are trying to replace, so a closed room with a dehumidifier running is often the better setup. Your contractor can compare indoor and outdoor humidity with a simple meter. Ask what they found. It is a fair question and it should have a clear answer.

The EPA's general advice is to keep indoor humidity under 60 percent, with 30 to 50 as the ideal. ^[1] During a drying job, equipment is commonly run well below that to pull moisture out of materials more quickly. Once drying is finished, a normal household target is what you go back to.

People often ask how many days this takes, and the honest response is that nobody can say until the materials are measured. A small clean spill on tile can be gone by the next day. Water that ran beneath a hardwood floor might take much longer, and a dense subfloor with vinyl over the top may not give up its water until the flooring comes off.

These are the things that tend to add time: multiple layers of flooring, because each layer slows evaporation; insulated exterior walls; a house without heat; water that sat for days before anyone found it; and damp outdoor air when ventilation is part of the plan. Rooms with closed cabinets are slow as well, since the toe kick area below them hides wet subfloor.

Shortcuts create problems of their own. Turning off equipment because the floor feels dry can leave a damp cavity behind that shows up weeks later as an odor. Painting over a water stain only hides the evidence. Reinstalling baseboard too early traps moisture at the bottom of the wall. Our guide on the first hours after a leak covers what you can do while you wait.

Drying itself is not usually the permit question. It tends to come up with what follows: replacing framing, moving plumbing, or changing electrical or mechanical systems. The City of Lake Stevens runs a permit center with online applications for residential building, mechanical, plumbing and demolition work, and it publishes a handout called Exempt Work (Interior) that helps sort out what needs a permit. The city notes that electrical permits come from Washington Labor & Industries instead. If your address falls outside the city limits, Snohomish County may be the one to ask. Confirm which applies to you before the repair stage begins.

Most drying jobs in the area begin with something ordinary. Check under sinks twice a year and look at the supply hoses to your washer, dishwasher and refrigerator. Know where your main valve is, and be sure everyone in the home can reach it and turn it. If you leave for more than a few days, closing the main can stop a small failure from turning into a floor-to-ceiling job.

Under the house, keep vents clear and the ground cover intact. In autumn, clean gutters and check that downspouts send water well away from the foundation. Inside, run bath fans and a kitchen hood during use. A small hygrometer is easy to keep an eye on, and it can tell you early when the house is holding more moisture than it should. A sudden rise usually has a cause you can find.

Whether to dry or replace comes down to the condition of the material, how contaminated the water was, and how long the material stayed wet. Framing is almost always dried, as it carries the house and tolerates wetting reasonably well when it dries soon after. Finishes are a different story. Swollen particleboard does not recover and delaminated plywood may lose strength. Wet drywall that crumbles at the bottom edge has passed the point of repair.

A helpful way to think about it is to ask what the material would look like after drying. If it would still be warped, stained, weak or smelly, then drying it was not the goal. Removal becomes a way of getting air to the structure more quickly. If a contractor wants to remove something that seems sound to you, ask to see the reading on it. If they want to leave something soft or discolored in place, ask why. Both questions are reasonable.

Ask to walk the job with the final readings in hand before the machines go, so that you can see which spots were tested.