Mold prevention in newer homeson Cavalero Hill

The city's comprehensive plan says that large portions of Lake Stevens developed in the past several decades, leaving a relatively new housing stock. ^[1] Newer houses generally let less air leak in and out. That saves heat, but it also means moisture from showers, cooking and a recent water loss stays indoors until a fan, a dehumidifier or a ventilation system takes it out. After a leak, a tight house can hold a damp atmosphere for days even though nothing looks wet any more.

Modern materials also matter. Paper-faced drywall, oriented strand board and composite trim all react badly to staying wet, and engineered floors can hide water beneath them. A newer house may feel very solid and still have a hidden wet patch in a wall cavity. The answer is the same as for any house, only more so: dry quickly, measure and control the humidity. Our main mold prevention page has the basics.

Attics show a different side of the moisture problem. If a bath fan duct has come loose, warm moist air goes straight into the attic every time someone showers. In winter that moisture condenses on the cold underside of the roof sheathing, and dark staining can spread across the plywood or oriented strand board. People usually find this when a roofer happens to point it out, or when they see frost on nail tips on a very cold morning.

A roof leak on the hill may be a windstorm issue, with rain getting past flashing or vents. It wets insulation first, and it may not reach the ceiling for some time. Take a look in the attic with a flashlight after big storms, and do so from the hatch if you can without stepping on anything unsafe. Note any dark staining, wet insulation or daylight around vents. If you find staining over a wide area, ask someone to look into the cause, not only to treat the surface.

Sloped lots and two-story walls tend to catch the wind, and outside corners on exposed sides of a house may stay colder than the rest. In a long wet spell, those corners can collect condensation, especially behind furniture. Published Everett normals give about 5.8 inches for November and about 5 each in December and January. So your house spends months in cool, damp conditions. Move beds and dressers a little away from outside walls, and open closet doors from time to time.

Below the house, a wet uphill end of the crawlspace may add moisture to the air under the floor. If rooms at that end smell musty each winter, check there first. Read our crawlspace water damage page if you find wet insulation.

The EPA considers a small area to be under about 10 square feet, roughly a 3-foot by 3-foot patch, and says you can usually handle that yourself in most cases. ^[3] Washington's Department of Health gives the same measure, and advises hiring a professional if the mold involves sewage or is out of sight. Fix the moisture first. Use detergent and water on hard surfaces, dry completely and do not paint or caulk over mold, as the EPA warns that paint is likely to peel.

Porous items like carpet and ceiling tiles may need discarding once moldy. Leave the HVAC off if you suspect contamination, since it could carry mold through the house. Keep in mind that Washington has no specific certification requirements for mold or water damage work, according to the Department of Health, so check that any firm is licensed, bonded and insured using the Washington L&I Verify tool. ^[6] Ask them how they will find and stop the moisture.