How do you check for mold behind drywall?

Author: Prof. Joesph Bergnaum DDS  |  Last update: Tuesday, September 2, 2025

If you think you have a mold problem, get on your hands and knees and smell the electrical outlets. As silly as it sounds, this is not a practical joke. Outlets have better access to the area behind walls, and smelling them can help pinpoint the mold problem. If mold is there, you'll be able to smell it.

Is there a way to test for mold behind drywall?

To tell if mold is inside your walls, professionals will take samples from the affected area through a swab test, bulk sampling (taking a piece of your drywall), and/or air test. After sample collection, they will take the samples to a laboratory for testing.

What are the first signs of mold on walls?

You can usually see or smell a mold problem. Mold can appear as slightly fuzzy, discolored, or slimy patches that increase in size as they grow. Most molds produce musty odors that are the first indication of a problem. Mold can grow anywhere there is adequate moisture or a water problem.

How do professionals find mold in walls?

The inspector will use specialized tools to identify moisture sources and areas with elevated humidity levels. 4. Sampling: Your inspector may collect air or surface samples. Air samples help identify mold spore levels in indoor air quality, while surface samples can pinpoint the presence of mold on specific materials.

What does mold look like behind drywall?

Dark Spots: These are frequently the first noticeable signs. The colors can range from black to shades of brown or green. Their presence often signifies active mold growth.

Early Stage Mould Inspection Tips from a Mold Inspector

How to get rid of mold behind drywall?

How to Remove Mold from Inside Walls
  1. Contain Your Work Area. Before you start work, protect the other areas of your home. ...
  2. Remove the Affected Drywall. ...
  3. Remove the Insulation. ...
  4. Dry Out the Area. ...
  5. Vacuum the Space. ...
  6. Kill the Mold. ...
  7. Contain and Encapsulate the Mold. ...
  8. Close and Rebuild the Wall.

Can you do a mold test on yourself?

Each test kit is designed to analyze yourself or surfaces samples for harmful mold growth. Easy Process. Our test kits don't require a prescription or even an office visit.

What are signs of mold sickness?

If you have a mold allergy, your immune system overreacts when you breathe in mold spores. A mold allergy can cause coughing, itchy eyes and other symptoms that make you miserable. In some people, a mold allergy is linked to asthma and exposure causes restricted breathing and other airway symptoms.

What tool is used to detect mold in walls?

Moisture meters not only help identify the reasons for existing mold growth but also aid in preventing conditions that could lead to mold in the future.

Can mold behind drywall affect you?

Mold behind drywall can be very harmful to our health. Black mold is especially dangerous because of its severe effects. It can cause serious respiratory problems. People who breathe in mold spores often get respiratory infections.

How much does a mold inspection cost?

In his California market, the cost can range from $275 for a simple visit to $2,900 for a complex inspection. For homes under 4,000 square feet, Angi estimates the average cost is generally between $300 and $400, whereas larger homes may see prices between $700 and $1,000.

Does homeowners insurance cover mold?

Homeowners insurance doesn't usually cover mold damage or removal unless it's the result of a covered peril. If the mold in your residence was caused by something sudden or accidental, such as a bursting pipe or some other covered incident on your policy, you may be protected.

How to tell if your house is toxic?

If you suspect your asthma worsens or is more severe than usual, contact your doctor or medical professional.
  1. Bad Smells In The Home. When there's a bad smell in the home, you can tell. ...
  2. Peeling Wallpaper. ...
  3. Spots On The Wall. ...
  4. Bad Allergies Won't Go Away. ...
  5. Visible Mold Growth. ...
  6. Past Water Damage.

How do you check behind drywall?

To detect pipes or wiring behind drywall, use a stud finder with live wire detection or a multi-function detector. Avoid drilling near electrical outlets and switch plates as wiring is likely in those areas.

How do I test my house for hidden mold?

Home testing kits are typically petrie dishes that you place in a location where you suspect harmful mold might be growing. The dish is meant to collect spores over the course of 24 to 48 hours and then grow the spores into mold, which is then evaluated by a lab or visually inspected.

How long does it take for mold to grow behind drywall?

mildew and mold will develop within 24-48 hours of water exposure. Even worse, it will continue to grow until steps are taken to eliminate the source of moisture, and effectively deal with the mold problem. Use the diagram on the facing page to assess the extent of mold in your home.

How to test for mold behind drywall?

To actually find out if there is mold growing in a wall cavity, a laboratory sample is needed. The least invasive way of collecting a sample inside a wall cavity is to take a wall-check sample. A wall-check is an air sample that is collected directly from inside the wall cavity.

What do professionals use to detect mold?

It's best to hire a professional mold inspector for accurate results. They have the experience and equipment such as digital moisture meters, hygrometers, infrared cameras, and borescopes, to detect and identify mold growth, and DIY kits may be unreliable.

Can you check for mold without opening walls?

How do I detect black mold inside my walls in the first place? -Bella, Los Angeles. You can purchase a moisture reading device and check if a particular area has moisture. If there is moisture, then it's more than likely there's going to be mold.

How long does it take to get sick from mold exposure?

According to the CDC, people usually experience their first symptoms within 2 to 9 hours of their first exposure. On the other hand, some people could go for weeks or months before feeling sick if their exposure is limited enough. This is why it is also important to check damp, dark areas of your home for mold.

Can you clean up mold yourself?

Scrub mold off hard surfaces with detergent and water, and dry completely. Fix plumbing leaks and other water problems as soon as possible. Dry all items completely. Absorbent or porous materials, such as ceiling tiles and carpet, may have to be thrown away if they become moldy.

How do you know if your house has mold in the walls?

How to Detect Mold in Walls
  • Water stains.
  • Dark rings.
  • Discoloration.
  • Deterioration like peeling, bubbling, or cracking of the paint or wallpaper.

Is there a device that detects mold?

Mold Detection

In the same way that smoke detectors identify smoke, not fire, the Biomatrix Mold Monitor identifies unseen moisture that can lead to widespread mold growth.

What are symptoms of black mold exposure?

The most common symptoms of black mold exposure include:
  • Sneezing.
  • Coughing.
  • Nasal congestion.
  • Postnasal drip.
  • Red eyes.

How to remove mold from walls?

How to Clean Mould on Walls in Three Steps
  1. Mix one part bleach to four parts water.
  2. Wipe and gently scrub the mould until it is gone.
  3. Finish by wiping away the bleach mixture and dry the area well with a soft cloth.

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