Household Mold: Five Key Problems and Their Solutions

Words by
Sean Moss
Household Mold: Five Key Problems and Their Solutions hero image
In our damp climate, mold is an issue for most homeowners, whether it's your attic or your bathroom. Home inspector Sean Moss offers great preventive tips

Living with the threat of mold in our homes is an everyday reality that few homeowners can avoid – especially at this time of year.

Mold needs moisture to grow, so your home needs to be dry. However, even a dry home doesn’t mean that mold is eradicated. In fact, mold spores can lay dormant for long periods of time until the right temperature, moisture and nutrients become available.

Mold survives on anything organic such as paper, cardboard, wood, carpets, leather or even the old cheese in your refrigerator (gross, but true…).

Heath issues associated with prolonged exposure to mold, especially for young children, the elderly and those with respiratory issues is already a large-scale concern. Since we can’t get rid of it completely, we should make every effort to control it. Understanding where it is likely to occur will help in preventing issues from occurring.

Here are areas where household mold can be found and the best ways to deal with it.

How to Remove Bathroom Mold


The high humidity levels generated from showering and bathing, causes mold growth anywhere dust and/or dirt accumulates. The shower and walls can be especially problematic. Caulking along the corners and base of the shower will discolour and become moldy. When grout sealing has been neglected, cracks develop in the mortar between the tiles. At this point moisture seeps in behind the walls, through the cracks by way of “capillary action”. Overtime the moisture can’t escape, so it builds up…resulting in mold growth and damage to the drywall, or worse the structure. Most of us are unaware of this issue until the tiles become loose, it smells musty or they renovate.

In other cases, a strong mildew/moldy odour may develop (especially after a vacation). You’ll look everywhere, but won’t be able to find it. More often then not, it’s from the shower drain. When the shower hasn’t been used after a few days, it begins to dry out. Mold then develops on the leftover debris, hair etc inside the drainpipe.

Sweaty toilets contribute to mold issues along the floor, and most visibly under the toilet tank. Over time, condensation drips onto the floor, contributing to mold growth and damage. Older, loose toilets can result in leaks below the surface when the wax seal cracks and breaks. This is usually harder to detect, unless you see a leak on the ceiling below the bathroom, notice the discolouration on a vinyl or wood based floor or use a moisture meter or have a water detection alarm.


Always run the fan before, while and after a bath or shower for at least 45 minutes. In addition, remove your wet towels, all dirt, dust and debris. Replace all discoloured caulk, while sealing the grout lines. You can monitor the humidity levels by purchasing a hygrometer. In our environment, you want to keep it 55% or lower. Also, you can paint the bathroom ceilings and walls with Anti-microbial paint, which can be found at most paint & hardware stores or online. This reduces mold growth on surfaces.

Regarding the drain, take the cover off, clean it out frequently… especially before you leave for vacation. After this, pour hydrogen peroxide down the drain to essentially disinfect and kill any remaining mold. If any smell is lingering when you return, run the shower to fill the trap below and pour more hydrogen peroxide if needed.

Check your toilet tank inside and out. (This is the reservoir containing the water which discharges into the bowl, while filling up after the toilet has been flushed) If the toilet is 15 years or older, it should be replaced. A factory-insulated tank will not sweat, unless it is defective, leaking from the supply line, tank/bowl connection, tank bolts or just not insulated. In any case, a plumber or bathroom contractor should rectify the issue as soon as possible.

How to Remove Attic Mold


This is common due to poor ventilation. In winter, when the temperature on the attic sheathing is cold, condensation forms. Left unchecked, mold will eventually damage the sheathing. Other notable sources of attic mold result from roof leaks and vapor migration from high humidity inside the home.


Ensure the attic hatch is properly weather stripped & insulated to prevent air leakage. Topping up the insulation level to an R-Value (resistance value) of 40-50 is also recommended. All bathroom and laundry vents should be insulated and vented through the roof, not discharging inside the attic. The exhaust ducts should be made of rigid metal ducts rather than the common plastic or foil covered corrugated variety. In addition, baffles should be installed on the sheathing between the rafters, along with roof or ridge vents to allow air to escape. Roof leaks should be prevented through annual inspections and repairs.

How to Remove Basement Mold


This is most common in homes that are poorly sloped, missing waterproof membranes, have broken drain tile or foundation cracks. All of these conditions contribute to moisture into the home. Further, storage items such as cardboard boxes, documents, photos or furniture are often strategically placed in contact with the foundation wall for long periods of time. As the moisture seeps through the foundation, mold begins to grow, while damaging these items before the issue is detected.


Purchase a hygrometer for the basement. This device will measure the indoor humidity. In our temperate environment, it should never be more than 55 per cent inside. Heat the basement and use a dehumidifier to reduce the moisture.

From the outside, have a drainage company scope the perimeter drainage to determine its condition. If damaged, replace older clay, concrete or plastic corrugated materials with the modern PVC drain pipe. (This can be expensive) At the same time, seal all cracks and have a proper moisture barrier installed. Place drainage stone around the perimeter, while keeping all vegetation away from the home. Have your sump inspected every two to three years by a drainage contractor.

How to Remove Kitchen Mold


Can usually be found under the sink, behind the refrigerator, or near the dishwasher, walls and ceilings. These are the most common areas of mold growth simply because small leaks often go unnoticed for quite some time. Poor ventilation while cooking contributes to indoor humidity.


Periodically check under the sink, along the floor by the refrigerator and dishwasher for leaks. Clean and caulk all areas around the sink, seams and corners to reduce water damage to counter tops. Always be at home when you run the dishwasher to catch any leaks. Always run the kitchen fan while cooking. Recirculating fans contribute to indoor humidity, so ideally, all fans should vent outside. Consider a water leak alarm/device for appliances such as dishwashers and refrigerators. They can also be installed near the water heater, washing machine, under sinks, by toilets.

How to Remove Window and Surface Mold


This is commonly found the sills of wood or metal-framed windows, but can to a lesser extent be found on vinyl-framed windows. When dust and dirt accumulates, in combination with the moisture from window condensation, mold will grow. Ceilings, exterior (outside) facing walls, closet walls, or surfaces near kitchens and bathrooms should be examined for signs of mold.


Since windows are always the coldest surface of the home, it is important to keep them warm and dry. The mold and mildew can be cleaned off with a mold remover from your local hardware store or a simple green solution consisting of one part vinegar, one part dish soap and 10 parts water. Mix together in a spray bottle. Continue to clean all dust, dirt and wipe away excess moisture, especially in the winter. Borax and vinegar or baking soda work as well. Avoid using bleach, as it is toxic. Be sure to remove all dust when possible.

Finally, if you have a crawlspace, see my article Mold in a Crawlspace and How to Deal with It.

Remember, the most important part of managing the mold in your home is to identify and remove the moisture source(s) as soon as possible.

A certified mold inspector can investigate any mold-related concerns. If significant mold growth has been discovered, call a mold remediation contractor for safe and proper removal. If your home smells musty, but cannot find the source of the mold, you may need to have an air quality test done to see if there is high spore activity.

For any questions in this topic or anything home inspection-related, feel free to contact me at 604-729-4261 or by email at [email protected].


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