Mold in a New Construction Home

Why new houses get mold

People are surprised to find mold in a new home, but the conditions are common here. Framing lumber goes up in rain and snow through a Spokane winter, and walls sometimes get closed in before the wood has dried. Concrete, drywall mud, and paint release a lot of water into the house over the first year. Modern houses are also built tight, which is good for energy bills and bad for moisture if ventilation is missing or not working.

Put those together with a first winter of cold outside surfaces and you get condensation in places nobody is looking.

Where we find it

• Attic sheathing, often on the north side, when bath fans are vented into the attic instead of outside or when soffit vents are blocked by insulation.
• Rim joists in basements and crawl spaces, where warm indoor air meets the coldest wood in the house.
• Crawl spaces with gaps in the vapor barrier or poor drainage around the foundation.
• Closets on exterior walls and behind furniture pushed against outside walls.
• Window frames and sills that run wet every cold morning.

Staining on framing versus an active problem

Some discoloration on framing lumber comes from the yard or the lumber yard and is not growing anymore. What matters is whether the wood is still wet and whether growth is active. Moisture readings and lab samples tell the difference, and that difference is exactly what a builder will ask about.

Documentation for the builder

Most builders offer a one-year workmanship warranty, and many carry longer coverage on structural items. The terms of your warranty decide what is covered, so read yours and act while the window is open. An independent report with photos, moisture readings, lab results, and a description of the likely moisture source gives the builder something specific to respond to instead of a general complaint.

We are not affiliated with any builder or remediation company. We test and report. What happens next is between you and the builder, and the report is written so it holds up to that conversation.

Buying a new build

If you are under contract on a new or nearly new house, the same testing fits inside your inspection window. See buying a house with mold for how the timing works.

Frequently asked questions

Is some mold on framing lumber normal? Surface staining on lumber is common and often came with the wood. The question is whether moisture is still present and growth is active. Moisture readings and lab results answer that.

Should the builder pay for the fix? That depends on your warranty and the cause. We are not attorneys and do not give legal advice. We provide the documentation you need to make the request.

Can you test before closing on a new build? Yes. Testing fits inside a typical inspection contingency, and results come back quickly enough to use in negotiations.

Will the house keep growing mold after it dries out? Often a new house settles down after the first year once construction moisture is gone, but only if ventilation works and the source is fixed. Attic venting and bath fan ducting are the common problems to correct.