Not every patch of mold carries the same risk. Some species are little more than an ugly stain on a window sill. Others eat through drywall, and a few release compounds that make sensitive people ill. Telling them apart matters, because the type of mold growing in your house decides how urgent the problem is and how it has to be handled. This guide covers the three health classifications of mold and the twelve species found most often inside homes.
You cannot always name a species by eye, and a lab test is the only sure method. Still, colour, texture, odour and location narrow the field fast. At Mold Removal Winnipeg, we see the same short list of species over and over in older Winnipeg homes, especially after a wet spring or a basement backup. If you want to check the growth against a visual guide first, our article on what mold looks like sorts it by colour and by surface.
The Three Classifications of Mold
Indoor molds fall into three health groups. The groups overlap, and one species can belong to more than one of them. The classification tells you how much caution the cleanup needs, which matters more than the exact name.
Allergenic Molds
Allergenic molds are the most common and the least severe. They irritate the nose, eyes, throat and skin, and they can set off asthma symptoms. Most healthy people handle small amounts without trouble. Anyone who already has allergies or asthma reacts sooner and harder.
Pathogenic Molds
Pathogenic molds can cause infections. The risk falls mainly on people with weakened immune systems, infants, older adults and anyone recovering from a serious illness. A healthy adult may notice nothing at all, which is exactly why this growth gets ignored for too long.
Toxigenic Molds
Toxigenic molds produce mycotoxins, which are poisonous compounds released onto surfaces and into the air. These reach healthy people too, not only sensitive ones. Toxigenic growth belongs to trained technicians working behind containment, not to a homeowner with a spray bottle.
Not sure which group you are looking at? Testing settles it. Call (204) 789-1514 before you disturb the growth, because scrubbing it the wrong way pushes spores into the rest of the house.
Twelve Types of Mold Found in the Home
These twelve species cover the large majority of what we find in Winnipeg houses. For each one, note the colour, the texture and the material it is feeding on. Those three details together are a far better clue than colour alone, since most species shift colour as they age.
Acremonium
Acremonium is toxigenic. It grows where condensation collects: humidifier tanks, drain pans, cooling coils and window sealant. It begins as a small damp patch and dries into a fine powder. Colours run from white and pink through grey and orange. Have it tested instead of wiping it away.
Alternaria
Alternaria is the most common allergenic mold found indoors. It is dark green or brown with a fuzzy, velvety surface. It settles in showers, under leaky faucets, around bathtubs and below sinks. It spreads quickly, and it returns unless the leak feeding it is repaired first.
Aspergillus
Aspergillus is very common indoors and shows up in brown, green and yellow shades. Some strains are allergenic and some produce mycotoxins. It grows in damp drains, HVAC systems, insulation and stored food. Exposure is linked to asthma symptoms, respiratory irritation and lung infections in people with weak immunity.
Aureobasidium
Aureobasidium hides behind wallpaper, on painted wood and around window frames where moisture gets trapped. It looks pink or pale when it starts and darkens to brown or black with age. Contact with it can cause a skin rash, so do not handle it with bare hands.
Chaetomium
Chaetomium starts white and cotton-like, then darkens toward grey and black. Its strong musty odour is often the first clue that something is wrong. It appears in drywall, under leaking roofs, in basements and around failed plumbing. It is a reliable sign of long-running water damage.
Cladosporium
Cladosporium grows in both warm and cold conditions, which makes it a frequent find in Manitoba homes. It is dark olive green to brown with a velvety texture, and it favours fabric, carpet, upholstery and wood. It commonly triggers a runny nose, sore throat, itchy eyes and skin rashes.
Fusarium
Fusarium is both allergenic and toxigenic. It grows in cold and warm conditions and usually appears pink, red or white. Look for it in carpet, wallpaper and fabric that stayed wet after a flood. Reported symptoms include skin rash and irritation of the eyes, nose and throat.
Recognize one of these already? Do not start cleaning yet. Call (204) 789-1514 and we will confirm the species and measure the affected area first.
Mucor
Mucor grows in thick white or grey patches. It favours damp carpet, wallpaper, drywall and the area around HVAC systems and window condensation. It is allergenic and mostly affects breathing. People with asthma react to it strongly, so keep them out of the room while it is removed.
Penicillium
Penicillium is blue or blue-green with a fuzzy, velvety surface. It spreads fast through insulation, carpet, wallpaper and furniture that has been wet. It shares a name with the antibiotic, but breathing it indoors is not harmless. It is associated with asthma symptoms and ongoing sinus irritation.
Stachybotrys Chartarum
Stachybotrys chartarum is the species most people mean by black mold. It is dark green to black and usually looks slimy rather than fuzzy. It needs material that stays wet and is high in cellulose: drywall paper, cardboard and wood. It usually grows out of sight, behind walls, under floorboards or above a ceiling, so it can spread for months before anyone notices. Our guide to black mold covers it in depth.
Trichoderma
Trichoderma is white to green with a woolly texture that spreads out in patches. Several of its species are harmless, but others produce mycotoxins much like those of black mold. It is also destructive. Its enzymes break down wood, wallpaper and fabric, so it damages the building itself.
Ulocladium
Ulocladium is black or dark grey-green, and it needs a lot of water, so it turns up in homes that have flooded or held a long slow leak. Bathrooms, kitchens and window sills are typical spots. It often grows beside Stachybotrys and Fusarium, which is why testing matters before cleaning.
What To Do Once You Know the Type
Naming the species tells you how careful to be, not whether to act. Any growth larger than about one square metre needs professional containment. Smaller patches still need the moisture source repaired, or the mold comes back in the same spot within weeks. If the growth is flat, powdery and sitting on top of the surface, you may be looking at mildew instead, and our mold versus mildew comparison sorts that out. Either way, find out what caused it so the repair holds.
Book an inspection through our contact page and we will identify the growth, measure the affected area and hand you a written scope before any work begins.
Stop Mold Before It Spreads
Mold is cheaper and easier to deal with early, and the species you cannot see behind the wall is usually the one doing the damage. Our IICRC certified technicians are available 24/7, and we work directly with insurers so you are not chasing paperwork. Call (204) 789-1514 or reach us through our contact page to book an inspection anywhere in Winnipeg.
