It is possible that rain can cause structural damage to houses under construction. Particle board will definitely become compromised if it gets wet, which is why it’s rarely used for sheathing.

Plywood is the most desirable sheathing because of its moisture resistance. However, it’s also expensive, which is why many builders choose oriented strand board (OSB). OSB is also water-resistant, but under persistent moisture, it can swell, and once it does, it will not return to its original dimensions.

“Houses built in the wetter months also tend to have dimensional challenges that homes built during dryer times of the year don’t experience,” says Josh Rudin, owner of ASAP Restoration. “This means that a straight piece of wood today might turn into a corkscrew come the dry season.”

While that likely won’t affect the structure’s safety, it could lead to creaking, cracking and other strange noises, especially when outside temperatures change.

Mold

Mold needs prolonged moisture to grow, so if a house frame gets wet but dries in a timely fashion, mold shouldn’t be an issue. But if the frame or sheathing is exposed to prolonged moisture or is damp when it is sealed up with house wrap, insulation and drywall, that moisture inside can manifest into mold.

“Concerns should be focused on the prolonged moisture,” says Vent. “If I turned on the hose and wet the wood subfloor, and then allowed it to dry out over the next few days, there would be a much less likelihood for mold growth than if I sprayed that same hose every day for three days, or if after I wet that wood floor, I quickly installed vinyl plank flooring before it had a chance to dry.”

How Do I Know If My House Was Built in the Rainy Season?

If your house was built in the rain, you might see signs of water damage, like staining on drywall and exposed wood or rust on metal components, all of which could be signs of serious structural problems.

“Even finished homes can show signs of stress in the form of cracks in drywall and uneven surfaces,” says Rudin. “Typically, the building inspector will force corrections on things like this before they get that far down the line, but it is still possible they’ve missed them, or those clues weren’t present yet during the inspection.”

Otherwise, to gauge how concerned you should be, you can check weather records for when your house was built, plus ask the builder about their water mitigation practices, such as whether they cover frames during stormy weather or promptly clear standing water from foundations.

“Everyone should assume that as their home was being built it, experience rain or other weather,” says Vent. But “I also wouldn’t be extremely alarmed if my home got wet during the initial stages on construction. It happens, but how the home builder is prepared to deal with it should be a point of understanding.”

What to Do to Avoid Mold If My House was Built in the Rain

If you are worried or suspect your home was built carelessly during rain or snow, hire a professional inspector to evaluate it for high humidity, wet building materials, construction flaws and mold, says Vent. “Mold inspectors, home Inspectors, industrial hygienists and indoor environmental professional’s (IEP’s) are a great place to start, and often do not come at a huge price point,” he says.

If they find mold, have it professionally remediated, says Rudin. Otherwise, try to keep everything as dry as possible. Use fans and dehumidifiers to vent moisture-prone areas like crawlspaces and basements, prevent condensation on windows and seal up any areas that might be letting moisture into your home.

“This means keeping wood, drywall and any fabrics or porous surfaces free from standing water,” says Rudin. “Mold spores live in the air around us all the time, and there is no way to prevent their growth other than to prevent the environment that they need to live from existing inside your home.”

About the Experts

• Russell Vent is the Vice President of Paul Davis Restoration of Greater Rochester, New York, a disaster management, mitigation and restoration network with 350 locations in the U.S. and Canada.
• Josh Rudin is the owner of ASAP Restoration in Tempe Arizona. He started the company as a one-man operation in 2008, and today it has grown into one of the city’s top disaster mitigation specialists.