Removing Mold From Wall Cavities

Written by richard kalinowski
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Removing Mold From Wall Cavities
Bleach eliminates most mould spores but it won't kill them all. (cleaning mailbox 2. image by mdb from

Provided the right moisture content and temperature, mould can grow within wall cavities. Mold is unhealthy and should be removed right away. According to House Painting Guru, a home design and maintenance website, inhaling mould spores can lead to fatigue, blood pressure irregularities, digestive problems, nose bleeds, and many more symptoms. Luckily, with the right know-how, you can remove mould from wall cavities in just a few steps.

Skill level:

Things you need

  • Respirator mask
  • Rubber gloves
  • Rags
  • Halogen light
  • Household mould and mildew remover
  • Bleach
  • Paper towels
  • Drywall saw
  • Insulation
  • Drywall
  • Spackle

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  1. 1

    Put on a respirator mask and wear rubber gloves. It’s important to protect yourself from mould spores whenever removing potentially hazardous mould deposits.

  2. 2

    Illuminate the wall cavity using a halogen light or other bright light source. Black mould commonly grows in wall cavities, and this kind of mould is understandably difficult to see in the dark. You must make sure you can see clearly into the wall cavity.

  3. 3

    Spray a general purpose mould and mildew remover on the affected area. Let the mould remover sit for at least five minutes before wiping it away using a disposable rag. This should help kill most of the mould spores and remove visible traces of mould within the wall cavity.

  4. 4

    Dip a second rag in undiluted bleach and apply the bleach to the wall cavity’s surface. Let the bleach sit for at least 15 minutes before sopping up any excess bleach with paper towels. As explained by House Painting Guru, bleach will never completely kill all of the existing mould or penetrate deep enough to eradicate microscopic mould spores. However, this cleaning method can help reduce mould content, and this is important to prevent the release and spread of spores during the next removal steps.

  5. 5

    Cut out any pieces of mouldy drywall from within the wall cavity using a drywall saw. As explained by the Toxic Black Mold Information Center, mould can become ingrained in drywall, and effective mould removal requires complete removal and disposal of the infected wall. Wall removal should only be attempted after the mould has been cleaned to the best of your ability.

  6. 6

    Remove all insulation from the recently cut section of the wall. Even if the insulation looks uncontaminated, mould may be hidden deep within the extremely porous insulation fibres.

  7. 7

    Search for any sources of moisture within the exposed wall. Wall cavities naturally accumulate more moisture than flatter wall surfaces; however, it is possible that a leaking pipe or other water source is responsible for excessive moisture. You should only replace the wall section after any sources of moisture are fixed, because extra moisture can cause mould to grow again in the future.

  8. 8

    Apply bleach to the wooden studs and let it sit for at least 15 minutes before sopping up excess bleach. Bleach serves as a precautionary measure just in case there are unseen mould spores in the wooden studs. However, if you notice visible mould deposits, you need to hire a contractor to replace the studs.

  9. 9

    Insert new insulation and patch the hole in the wall using drywall and spackle. The mould has now been entirely removed, and your wall cavity is once again safe.

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