The short answer
What to Do If You Suspect Mold
If you spot any of these signs, do not ignore them. Gently press the wallpaper to see if it yields or feels spongy, which suggests moisture behind it. Carefully peel back a small corner or edge to inspect the back of the paper and the wall surface. Wear gloves and a mask to avoid inhaling mold spores.
For a more accurate check, use a moisture meter, which you can buy at a hardware store. Insert the pins into the wall through the wallpaper to measure dampness. High readings indicate that moisture is present, creating ideal conditions for mold. If you are unsure, consider hiring a professional for a water damage inspection to assess the extent.
- Dark or greenish stains on the wallpaper
- Bubbling, peeling, or lifting edges
- Musty or earthy smell in the room
- Damp or spongy feel when pressed
- Visible water stains near seams or corners
- High moisture meter readings
Why Mold Grows Behind Wallpaper
Mold needs moisture, warmth, and organic material to thrive, and wallpaper provides a perfect surface. Condensation from cold walls, plumbing leaks, or roof leaks can create damp conditions behind the paper. In areas with high humidity, such as bathrooms or kitchens, mold can grow quickly if moisture is not controlled.
Wallpaper acts as a barrier, trapping moisture against the wall and preventing it from drying out. This creates a hidden environment where mold can spread unnoticed. In climates with mild, wet winters, keeping indoor humidity low and fixing leaks promptly can help prevent mold growth.
How to Remove Mold Safely
Once you confirm mold, remove the affected wallpaper carefully to avoid spreading spores. Seal the area with plastic sheeting and turn off any fans or HVAC systems to prevent spores from traveling. Wear protective gear, including gloves, goggles, and an N95 respirator, and dispose of contaminated materials in sealed bags.
Clean the wall with a solution of water and mild detergent or a commercial mold remover. Do not use bleach, as it can be harmful and may not penetrate porous surfaces. After cleaning, dry the area thoroughly with fans or a dehumidifier. For extensive mold growth, consult a mold professional to ensure safe and thorough removal.
When to Call the Pros
If mold covers a large area, is behind multiple walls, or you have health concerns, call local water damage pros. They have specialized equipment to detect hidden moisture and mold, and they can safely remove contaminated materials. They also provide structural drying and dehumidification to prevent recurrence.
The pros can also perform moisture mapping to identify all affected areas and recommend repairs. Attempting to handle extensive mold yourself can be risky and may not solve the underlying moisture problem. In such cases, seeking professional help ensures the job is done thoroughly and safely.
- Large areas of visible mold growth
- Mold behind multiple walls or in hard-to-reach places
- Persistent musty odor that returns after cleaning
- Health symptoms like coughing or sneezing near the area
- Recurring moisture problems or leaks
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Call Now (425) 407-5186Frequently asked questions
Can I paint over mold behind wallpaper?
Painting over mold is not a solution. The mold will continue to grow and eventually show through the paint. You must remove the wallpaper, clean the mold, and address the moisture source before repainting. Otherwise, the problem will persist.
How long does it take for mold to grow behind wallpaper?
Mold can begin to grow within 24 to 48 hours if moisture is present. However, visible signs may take days or weeks to appear, depending on temperature and humidity. By the time you notice stains or odor, the mold may have already spread significantly.
Is mold behind wallpaper dangerous to health?
Mold can cause health issues, especially for people with allergies, asthma, or weakened immune systems. Symptoms may include sneezing, coughing, eye irritation, and respiratory problems. If you experience these symptoms, see a doctor. Promptly addressing mold growth reduces health risks.