Carpet Mould: Identification, Prevention and Removal

The Dangers of Mould

Moulds produce allergens, which are substances that can cause allergic reactions, as well as irritants and, in some cases, potentially toxic substances known as mycotoxins. Inhaling or touching mould or mould spores may cause allergic reactions in sensitive individuals. Allergic responses include hay fever-type symptoms, such as sneezing, runny nose, red eyes, and skin rash (dermatitis). Allergic reactions to mould are common. They can be immediate or delayed. Moulds can also cause asthma attacks in people with asthma who are allergic to mould. In addition, mould exposure can irritate the eyes, skin, nose, throat, and lungs of both mould-allergic and non-allergic people. Symptoms other than the allergic and irritant types are not commonly reported because of inhaling mould but can also occur.

Carpet at Risk

Carpeting is an area of your property that can be at high risk for mould growth. To grow, mould needs moisture, oxygen, a food source, and a surface to grow on. Mould spores

are commonly found naturally in the air. If spores land on a wet spot indoors that contains dust for them to feed on, mould growth will soon follow. Wall-to-wall carpeting, as well as area rugs, can provide an ample breeding ground for mould if conditions are right. At especially high risk for mould growth are carpeting located below ground level in basements, carpet in commonly moist or damp climates, and carpet that has been wet for any period.

Identifying Mould in Carpeting

Just because mould is not immediately apparent or visible on a carpet’s surface does not mean that mould growth is not in progress. Mould will probably only be visible on the surface of carpets in unusually severe cases of growth, such as carpet damaged in flooding that has remained wet for some time. The following are some examples of identifiable instances where mould growth has occurred or is likely to occur:

• Visible mould growth: As stated above, this can be a rare case, but sometimes it may be obvious from visual inspection that mould growth is occurring. The carpet in this condition is most likely not salvageable and should be disposed of and replaced. Often, even if mould growth is not visible on the top of carpeting, it may be occurring underneath the carpet where it can’t be easily seen. Carpet suspected of containing mould should always be examined on both sides.
• Carpet mildew: Any discolouration or odour on carpeting that might be described as mildew is probably a case of mould.
• Wet or water-damaged carpet: Any carpet that has been subjected to water damage from flooding or standing water will most likely need to be disposed of. Conditions are ripe for mould growth, in this case. Even if visibly apparent mould growth has not yet begun, it is highly likely to happen unless the carpet is completely removed, cleaned, and dried within 24 to 48 hours. Even then, removal and cleaning are not guaranteed to prevent mould growth. It is more likely that the carpet will need to be replaced.
• Wet underlay beneath carpet: If the underlay beneath the carpet has become wet for any reason, or has become moist from condensation, the padding as well as the carpet on top are at risk for mould growth. The padding may need to be replaced, as will the carpet, in some cases.
• Basement carpet: Carpeting in basements below grade level is especially at risk in areas where humidity is high, or where wide temperature swings can produce condensation.
• Odours and stains: There are a wide range of things that can cause odours and stains on carpets. If mould is suspected, samples can be taken and sent for analysis to determine if mould growth has occurred.

Preventing Mould Growth in Carpeting

The best method for combating mould is to not allow mould growth in the first place. The best way to do so is by ensuring that conditions conducive to growth do not exist. Below are some ways to prevent mould growth in carpets.

• Reduce indoor humidity. The use of dehumidifiers will help control moisture in the air, depriving mould spores of the water they need to grow into mould. A range of 30% to 60% humidity is acceptable for interiors.
• Install intelligently. Do not install carpeting in areas that are likely to be subject to frequent, high moisture. Carpet in a bathroom, for example, will quickly turn into a breeding ground for mould growth due to the high humidity from constant water use in that area.
• Choose high-quality carpet underlay. Solid, rubber-slab carpet padding with anti-microbial properties is available. It is slightly more expensive than other types of padding but can help prevent the growth of mould, especially in climates prone to periods of high humidity.
• Never allow standing water. The carpet exposed to standing water will quickly be ruined. If standing water ever occurs because of a leak or a spill, all carpeting exposed must be immediately cleaned and dried. The top and bottom surfaces of the carpet, any underlay, and the floor underneath must be cleaned and completely dried within a short period after exposure to standing water if the carpet is to be saved. If a large flood has occurred, or if standing water has been present for any extended period, the carpet will probably need to be replaced.
• Clean smart. When carpeting needs to be cleaned, try to use a dry form of cleaning, when possible. If any water, liquid, or other moisture has come in contact with the carpet during cleaning, be sure it is dried thoroughly afterwards.

Removing Mould from Carpet

In many cases, if mould has grown on the carpet, cleaning will not be possible. If growth has occurred on more than one area of the carpet, or if there is a large area of growth, the carpet will probably need to be replaced.

Small areas of growth that have been quickly identified can sometimes be dealt with. Detergent and water used with a steam-cleaning machine may be enough to clean the carpet thoroughly. It is then important to ensure that the carpet dries completely after cleaning to prevent the growth from recurring. Stronger cleaning agents can be substituted if detergent does not work. Anything stronger than detergent or common rug-cleaning products should first be tested on an inconspicuous area of the carpet to ensure that the rug will not be damaged during cleaning. About 24 hours is a reasonable amount of time to wait after testing to be sure that wider cleaning will not discolour or damage the carpet.

Another option in instances where mould growth is not widespread is to remove the ruined section of the carpet. If cleaning has been attempted unsuccessfully, the area of mould growth may be removed and replaced with a patch of similar carpet. Of course, this will only work in situations where aesthetics are not a big concern since exactly matching the patch to the original carpet may be difficult and the seam may be visible. If mould has grown in more than one area of the carpet, or if the area of growth is larger than a couple of feet, this will probably not be an effective method of mould removal.

As with all areas of the interior at risk for mould growth, prevention is the best method of control for carpet mould. Eliminating high-moisture conditions and preventing the risk of flooding or standing water will reduce the possibility of growth.