Musty Smell in the Walls

Updated February 21, 2017

Smelling a musty odour in a home commonly indicates the presence of mould or mildew. Detecting the odour along or near walls could indicate the presence of these damaging growths within the wall. Left unchecked, mould or mildew continues to grow. Mold and mildew discolours wall materials and advances the decomposition of the wall and can present a health hazard to occupants of the home.


Mold, a form of fungi, grows in moist and warm conditions. Mildew is a thin layer of mould. Mold grows when moist and warm conditions come in contact with organic materials such as paper, wood or natural cloth. In the case of a wall, this includes paper on the drywall and wood studs.

Cleaning the Mold

Cleaning mould and mildew without eliminating the moisture problem is fighting a losing battle. In a wall, this may require removing the wall sheathing. Other options include heating the home to 26.7 degrees Cor a few days to dry the wall materials. In a basement a dehumidifier helps reduce the moisture level. Wash the walls with a mixture of 2 tbsp of bleach and 1 pint of water. Rinse the wall with fresh water after about 15 minutes. Continue the home drying procedures immediately after washing the walls.

Removing the Odor

The odour commonly ends when the mould and mildew are eliminated. If the odour persists, wash the walls with a mix of 1 cup of bleach per gallon of water. Allow the solution to set on the walls about 15 minutes before rinsing with fresh water. Dry the area as quickly as possible.

Preventing Musty Smells

Moisture control is the key to mould control. Preventing mould and mildew prevents the musty odour. Limit humidity levels to common household comfort levels of 50 per cent. Along with the humidity level in the air, control accumulated water along the edges of walls. Maintaining good air circulation through the building helps keep surfaces dry and removes any odours from the enclosed area.

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About the Author

Keith Allen, a 1979 graduate of Valley City State College, has worked at a variety of jobs including computer operator, medical clinic manager, radio talk show host and potato sorter. For over five years he has worked as a newspaper reporter and historic researcher. His works have appeared in regional newspapers in North Dakota and in "North Dakota Horizons" and "Cowboys and Indians" magazines.