Short answer: A musty smell, dark stains, damp spots and allergy symptoms that get worse in one room are the main signs. Carpet and pad that stayed wet for more than 48 hours, or were soaked by dirty water, usually need to be replaced.
Carpet pad soaks up water and holds it out of sight. If it does not dry quickly, mold can grow underneath long before you see anything on top.
Signs of mold under carpet
- A musty or earthy smell, often stronger after you walk on it
- Dark or discolored spots on the carpet
- Carpet that stays damp or feels cool to the touch
- Stains on the baseboards nearby
- Allergy symptoms that get worse in that room
Why it happens
- A leak or flood that was not dried within 24 to 48 hours
- A basement or slab floor with moisture coming through
- High indoor humidity
- Spills or pet accidents that soaked the pad
Check it safely
- Wear gloves and a mask
- Lift a corner of the carpet near the smell or stain
- Look at the pad and the floor underneath for spots or dampness
- Put it back and keep the room ventilated
Can it be saved?
Small areas from a clean water spill that dried quickly can sometimes be cleaned. Pad that grew mold, carpet soaked by sewage or flood water, and carpet that stayed wet for days should be replaced, and the floor underneath cleaned and dried.
When to call a professional
Call a mold removal company if the area is larger than about 10 square feet, the smell is strong, or the water was dirty. They can find the moisture source and remove the carpet safely.
Frequently asked questions
Can I just clean the top of the carpet?
Not if mold is in the pad. It will keep growing underneath.
Does homeowners insurance cover mold under carpet?
Sometimes, if it came from a sudden covered leak. Slow leaks and humidity are usually not covered.
How do I prevent it?
Dry any spill or leak fast, keep humidity under about 50 percent, and use a vapor barrier in basements.
Related
Read our carpet water damage page and our mold after water damage guide.
For more background, see the EPA mold pages, and if you need help, Sifixit can connect you with a local provider.
This site is a free service to assist homeowners in connecting with local service contractors. All contractors are independent and this site does not warrant or guarantee any work performed. It is the responsibility of the homeowner to verify that the hired contractor furnishes the necessary license and insurance required for the work being performed. All persons depicted in a photo or video are actors or models and not contractors listed on this site.
More helpful guides
- Mold in a rental home: what tenants and landlords should knowTenants should report mold and any leak to the landlord in writing, with photos, and keep a copy.
- Mold on windows and window sills: causes and preventionMold on windows usually comes from condensation: warm, damp indoor air hits cold glass and frames, and water...
- Mold in AC vents and air ducts: signs and what to doDark spots on vent covers, a musty smell when the air conditioning runs and allergy symptoms that worsen...
- Bathroom mold: causes, cleaning and preventionBathroom mold grows because of steam, standing water and poor ventilation.
- Do I need mold testing? When it helps and when it does notIf you can see or smell mold, you usually do not need testing to know it must be...
- Mold vs mildew: how to tell the differenceMildew is a type of mold that grows flat on the surface, usually white, gray or yellow, and...