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Mould Growth in Carpeting

By Daniel da Chão

This article focuses on the prevention of mould (mould in English, and mold in the USA) growth, detection, and removal.

Mould is a significant health hazard. Mould refers to fungi that can grow on building surfaces and materials. Dampness and excess humidity encourage mould growth, especially if the building materials to which it attaches to give it both a place to settle upon and feed upon. Mould growth in homes and other buildings, increases the risk of respiratory allergic symptoms and will aggravate asthma and other respiratory issues in persons sensitive to mould if they inhale or handle mould. Mould produces allergens and irritants that can be potentially toxic. These irritants are known as mycotoxins. Symptoms include: irritation of the eyes, nose, skin, throat and lungs. Mould spores are commonly found in the air but become dangerous when their concentration surpasses a certain threshold and when these spores colonize living and working areas.

Because carpeting is subject to wetting due to water leaks and flooding, it provides the essential ingredients for mould growth: moisture, oxygen, food (fabric, dust and dirt), and a surface to grow upon. If mould spores land upon a humid or wet surface indoors that contains sufficient food for them to get a foothold, mould growth will ensue. Areas prone to mould growth are basements, washrooms, garages, wet areas and in homes in commonly humid climates.

Mould is not easily identified. It may very well be present, just not fully revealed. It will become visible on the surface of the carpet in severe cases of growth. This will usually occur in areas that got flooded or above concrete slabs that pass moisture up into carpeting: such as carpeting laid directly over concrete slabs on grade. You may take a sample and have it evaluated at a laboratory.

If one finds visible mould growth then it’s probable that the carpeting cannot be recovered. It should be removed. Reconsider replacing it with carpeting, wood or other flooring materials that can supply both a surface to attach to and food to feed on. Consider other options, like ceramic. If the mould growth is not visible, then it may be occurring on the underside of the carpeting. Always examine both sides of the carpet. You may be able to smell it.

Carpet mildew may be witnessed as discolouration or odour on the carpeting that might look like mildew. Treat it as mould and deal with the issue immediately. If you decide to clean it, keep monitoring the situation. If it perseveres, then remove the carpeting, deal with the leak or humidity issues, and replace the type of flooring product used.

Carpeting that has been exposed to flooding, extended water damage or standing water will probably need to be removed and disposed of. Even if mould growth cannot be seen, it must be immediately cleaned and thoroughly dried within 48 hours, but even doing this may not prevent mould growth and subsequent removal of the carpeting. This includes the wet padding below the carpet.

Prevention is key. To do so, the conditions to prevent mould growth are as follows:

· Reconsider the types of finishes you install. Do not install carpeting in wet or humid basements, washrooms, kitchens and even dining rooms. These are all places subject to water damage, humidity and spills.

· Reduce indoor humidity by using dehumidifiers to control interior humidity. A range of 30-60% is acceptable indoors and will deny spores the water they need to grow. If the basement or crawlspace is a source of water infiltration via the foundation walls or the slab, then resolve this issue first because it is not only introducing and maintaining the conditions that promote mould growth, but it is also promoting the decay of the foundations, the structure and other systems within the home. If you need a dehumidifier to keep your basement at an acceptable humidity level, then there’s probably an issue. Use it above grade, and deal with the issues below grade, instead of drawing in more moisture through the foundation.

· Some inspectors or builders would suggest using high-quality carpet padding made of solid, rubber carpet padding that may come with anti-microbial properties for the basement or other moist areas, but I would not even bother with making that kind of recommendation. Why waste your money entertaining that kind of risk. Get over the carpeting issue that exposes your home to the risk of mould growth. Carpeting should be kept to a bare minimum. Carpets accumulate dirt, dust, dander, hair, germs and other pollutants that can only hinder your family’s health and welfare. Health risks are: respiratory issues; allergies; skin irritation; weakened immune system; stomach illness and more. There are all kinds of articles on this subject on the internet.

· Deal with water damage and standing water or flooding issues immediately. Not just because of the potential for mould growth on carpets, but in other areas and materials comprising your home, like the wood structure.

If mould has grown on the carpet and this growth is widespread, its most probable that it will not be cleaned and removed definitively. Remove it and reconsider not using carpeting as a replacement.

If mould has grown in a small area, probably due to some neglect, you may be able to use detergent and steam-cleaning to clean the carpet thoroughly. It must dry completely. Allow for at least 24 hours before re-installing the carpeting.

Prevention is always the best means to deal with mould-related issues. First deal with the issue that got the carpet, the walls and other areas of the home moist or wet. Eliminate the issues that will lead to high humidity, condensation, flooding and leaks inside the home. Then select the kind of finishes most suitable to deal with moisture, flooding and other issues depending upon the situations that may have led to the mould issues in the first place. Open your mind to other finishes.

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