How To Detect Mold In Walls

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Mold is a dangerous fungus to have inside the home. It can cause structural damage to a house and health issues for humans.

Understanding how to detect mold in walls is an essential skill to have. You’ll be happy to know that detecting mold is relatively simple and doesn’t take an expert to find – I’ll share a few tips in this article.

If you or someone in your family has asthma or allergies, it’s even more important to know if mold exists in your house. Mold can also cause toxicity in humans and be an underlying cause of anxiety, fatigue, mental fogginess, and even depression.

I struggled with mold allergy (and many others) for years. I had always noticed a little bit of mold in the bathroom and around my windows but I didn’t think twice about it. Little did I know it may have been affecting my health.

How To Detect Mold In Walls

When assessing your house for mold you’ll want to check in specific places. 1st on your list should be the basement and the attic. The basement is especially prone to mold because there is generally less ventilation and higher humidity. If you don’t have a basement you might have a crawl space under the house – check the crawl space for water leaks and moisture.

It’s also wise to check your plumbing under the sink and the bathroom as both places often have mold associated with humidity and a lack of ventilation.

Mold, however, isn’t specific on where it grows. It can lurk in places you don’t see, like inside your walls!

There’s no need to worry if you have brick walls, but if you have drywall you should be certain there are no leaks inside. To do so you can use a checklist of 1) a visual inspection, 2) a physical inspection, and 3) a test cut inspection. We’ll review each method of inspection below.

#1 Visual Inspection

Visual inspections are usually the easiest and best ways to detect if mold is in your walls. You can check for damp areas on your drywall and look for watermarks.

Common places to see dampness is near the bottom of walls (due to gravity).

You can also look for watermarks where moisture has dried. Inspect areas of your walls near the plumbing (kitchens and bathrooms) as these places tend to have more leaks.

  • Look For Areas Of Dampness
  • Look For Water Marks
  • Look At Areas Near Plumbing

#2 Physical Inspection

A physical inspection will require you to move your hands along the wall. You can push lightly if you see damp areas or watermarks.

Wet areas near areas where walls meet the floor are important to discover because they can do damage to flooring.

During your inspection, you might want to remove the trim of your floor. Removing the trim is an easier step than removing the wall and can give you good evidence if there is water damage or mold growth.

  • Is The Wall Soft

#3 Internal Inspection

The last step to detect mold inside your walls is to look within. To avoid damage to the wall you’ll want your impact to be as minimal as possible so I recommend using preexisting holes in the wall (like an outlet) or making a small test cut that allows you to use a borescope.

If you use the hole from an outlet take precautions so you don’t electrocute yourself.

Before going inside the wall, check the attic space to ensure that water isn’t leaking into your wall from above (this will save you time).

A borescope is a helpful tool that fits into a small hole in the wall and provides an inside view. The Depstech borescope is perfect because it shows the view on your phone and it waterproof.

The small hole needed for a borescope can be easily patches or covered up by wall art or furniture.

  • Check The Attic and Insulation
  • Remove Outlet Plate (Use Borescope)
  • Make Test Cut (Use Borescope)


Detecting mold inside your walls isn’t a difficult process but it’s important to detect before you encounter larger problems. Mold can cause structural damage to a house and more importantly, it can cause health problems for your family.

In most cases, a simple visual inspection will be all that’s necessary.

There might be watermarks or soft spots on the drywall. If you see signs of water damage attempt to discern where the water is coming from and how long it’s been occurring.

If needed, you can use a borescope to look inside the wall. Using a borescope only requires a screw-sized hole in the wall. It’s a much better alternative to a large hole in the wall.

Mold is a common occurrence outdoors, however, it’s not meant to be in your home. To get rid of mold in your house, increase ventilation, install fans in the bathroom, and make sure pipes aren’t leaking. If you have a basement it’s wise to use a dehumidifier to reduce humidity.

Check out more information about mold allergy in the “indoor allergens” tab on the menu. I hope you improve your allergies and improve your home environment!

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