Mold Inspection DIY Guide

Room-by-room checklist to find hidden mold in your home

How to Use This

How to Use This: Walk through each room with this checklist and a flashlight. Start with bathrooms and basements — these are where mold grows most often. Check off each item as you inspect it.

Start Here

Start Here: Buy a hygrometer ($10-15 at any hardware store) and check your home's humidity. If it's consistently above 50%, focus on reducing moisture before inspecting for mold.

Ideal Humidity

30-50% (buy a hygrometer, $10-15)

Mold Growth Threshold

Above 60% humidity for 48+ hours

Bathroom

Check caulking around tub/shower for black or pink discoloration

Inspect under sink (look behind pipes at drywall)

Kitchen

Check under sink for leaks or water damage

Pull out refrigerator and inspect wall/floor behind it

Basement

Look for white mineral deposits on walls (efflorescence = water intrusion)

Check corners where walls meet floor for discoloration

Attic

Inspect roof sheathing (underside of roof) for dark staining

Check around roof penetrations (vents, chimney)

Bedrooms

Check window frames and sills for condensation or mold

Pull furniture away from exterior walls and inspect

HVAC System

Remove a supply vent cover and look inside ductwork with a flashlight

Check around AC unit for standing water or staining

Important

If you find mold covering more than 10 sq ft, or if it's in HVAC ducts, hire a professional remediation company (not just a handyman). DIY cleanup of large mold areas can spread spores throughout the house. Do NOT use bleach on porous materials — it doesn't kill mold roots in drywall or wood.

Important

If anyone in your family has unexplained respiratory symptoms, chronic fatigue, or recurring sinus infections, consult a healthcare provider about possible mold exposure. Some individuals are genetically more susceptible to mold illness.

Next Steps

Next Steps: If you found problem areas, address moisture sources first (fix leaks, improve ventilation, run a dehumidifier). Then review the Air Purifier Comparison Chart to add HEPA filtration in affected rooms.