The short answer
Fast enough that drying should start the same day. The EPA's strategies for responding to water damage are built around the first 24 to 48 hours, and its guidance notes that mold growth may have occurred even when materials are dried within 48 hours. Materials that stay wet longer are more likely to need removal.
On this page
What mold needs
Mold spores are already in indoor and outdoor air. They grow when they land on something damp that they can feed on, like the paper face of drywall, wood, carpet backing, cardboard or dust. Take away the moisture and growth stops, which is why every mold plan starts with drying and fixing the source.
What the EPA says about wet materials
- Ceiling tiles: discard and replace.
- Fiberglass and cellulose insulation: discard and replace.
- Drywall: may be dried in place if there's no obvious swelling and the seams are intact; otherwise remove and replace.
- Non-valuable books and papers: discard.
Those strategies apply to clean water. Sewage or other contaminated water calls for protective equipment, containment and a professional.
Signs mold has started
- a musty, earthy smell a few days after a leak
- spots or fuzz on baseboards, drywall, the back of furniture or stored boxes
- bubbling paint or stains that keep spreading
- symptoms like a stuffy nose or itchy eyes that are worse in one room
Small patch or a professional job?
The EPA's homeowner guidance says areas smaller than about 10 square feet, roughly 3 feet by 3 feet, can generally be cleaned by the homeowner once the moisture problem is fixed. Larger areas, mold inside walls or HVAC systems, mold after sewage or flooding, or anyone in the home with asthma, allergies or a weakened immune system are reasons to call a professional. The EPA also notes that when mold is visible, sampling is usually unnecessary. See mold remediation after water damage.
Preventing mold after a leak
- Get standing water out the same day.
- Remove wet rugs, cardboard boxes and papers from the area.
- Run dehumidifiers with windows and doors closed, and keep air moving across wet surfaces.
- Pull baseboards or open a small section of wall if water ran inside it, so the cavity can dry.
- Check readings with a moisture meter, or have a restoration company do it, before closing anything up.
Mold and Westfield basements
Westfield's summers are warm and humid, with average July highs of 82.8°F at Westfield-Barnes Regional Airport, and spring snowmelt and 48.39 inches of yearly precipitation keep many basements damp. A dehumidifier, good gutters and fast drying after any leak are the best defense. For drying and cleanup help, see our main page on water damage restoration in Westfield, MA.
Sources
- EPA, Mold Remediation in Schools and Commercial Buildings, Chapter 4 (responding to water damage within 24–48 hours)
- Westfield, Massachusetts (Wikipedia: 2020 Census population, geography, Westfield-Barnes Regional Airport climate normals, 1981–2010)
Frequently asked questions
Can mold grow in 24 hours?
Growth can begin quickly on wet materials, which is why the EPA's guidance focuses on responding within 24 to 48 hours.
Does all water-damaged drywall need to be replaced?
No. The EPA's guidance says drywall may be dried in place if there's no obvious swelling and the seams are intact.
Should I test for mold?
Usually not if you can see it. The EPA notes that when visible mold is present, sampling is usually unnecessary.