Most people do not recognize mold until it has been growing for months. It gets written off as dirt, a water stain, soot above a heat register or a discoloured patch of paint. Mold looks different depending on its species, its age and above all the material it is feeding on, so there is no single picture to match against. There are reliable patterns though. This guide covers them twice: once by colour and once by surface.
Two clues beat colour every time, and those are texture and smell. Mold is usually raised, irregular and either fuzzy or slimy, and it carries a musty odour that a stain does not. At Mold Removal Winnipeg, the calls that turn out to be nothing are almost always flat dry marks with no smell, and the serious ones often start with a smell and no visible growth at all.
What Mold Looks Like by Colour
Colour narrows the list of likely species, but nearly every species shifts colour as it matures. Treat it as a starting point, not an answer.
Black and Dark Green
The colour everyone worries about. Stachybotrys chartarum, the species usually meant by black mold, is dark green to black and tends to look slimy rather than fuzzy. Ulocladium is black or dark grey-green. Alternaria and Chaetomium both darken toward black with age, so a black patch is not automatically black mold.
Green and Olive
Cladosporium runs olive green through brown, with a velvety, furry texture, and it turns up on fabric, carpet and wood. Aspergillus often appears in green shades too. Green growth is the most common thing homeowners show us, and it covers a wide mix of species.
White and Grey
White growth gets mistaken for dust or cobweb. Chaetomium starts as white cotton-like fuzz before it darkens. Mucor forms thick white or grey patches near HVAC systems and window condensation. Trichoderma is white to green with a woolly look. Acremonium can start white as well.
Blue and Blue-Green
Penicillium is the classic blue or blue-green growth, fuzzy and velvety, and it spreads fast through wet insulation, carpet, wallpaper and furniture. Blue-green is also common on drywall, ceilings and concrete where the material has stayed damp for a long time.
Pink, Red and Orange
Fusarium usually appears pink, red or white, most often in carpet and fabric that stayed wet after a flood. Aureobasidium looks pink or pale before darkening to brown or black. Acremonium is sometimes orange. Pink and orange growth is easy to dismiss as staining, which is exactly why it gets left alone.
Brown and Yellow
Alternaria ranges from dark green to brown, fuzzy in texture, and it favours showers, bathtubs and the area under leaky faucets. Aspergillus shows up in browns and yellows as well, and Aureobasidium turns brown with age. On drywall, brown spots with yellow edges usually mean moisture sitting behind the sheet.
Colour alone will not tell you which species you have, but a lab test will. Call (204) 789-1514 before you touch the growth, because disturbing a colony scatters spores through the rest of the house. Our breakdown of the different types of mold covers each species in detail.
What Mold Looks Like on Different Surfaces
The same species looks quite different on two materials, because the surface decides how it spreads and how much of it shows.
On Wood
White, green, black or blue-green with a fuzzy texture, usually alongside discolouration and an earthy, musty smell. Moisture gets trapped between the fibres, so wood holds growth well. Check beams, joists and boards sitting under anything that has leaked from above.
On Drywall
Green, black or blue-green, patchy and flat against the surface, sometimes powdery. Drywall is absorbent, so growth here is rarely limited to what you can see. Paint may chip, bubble or peel as it spreads. Dark brown spots with yellow borders near the base of a wall usually mean water behind it.
On Carpet
Black or green, smooth and flat, often as greenish-black spots with dark edges. Patches range from pea sized to much larger. Carpet is absorbent and stays damp, especially in basements, and most carpet growth starts underneath, where nobody sees it. A musty smell with no visible spots is reason to lift a corner and look.
On Painted Walls
Black, green or blue-green, rough, bumpy and irregular. It can look like a layer of dust across the wall, except it does not wipe away, because it is decaying organic material. Wall growth almost always traces back to a leak above or water damage behind the surface.
Seeing growth on more than one surface usually means they share a moisture source. Call (204) 789-1514 and we will trace it to the source.
On Ceilings
Black, green or blue-green, usually smoother and more powdery than wall growth, sometimes with small bumps. Ceilings are flat, get very little air circulation and hold moisture, and warm air rises and stalls against them. Rings or patches near light fixtures and in corners point to a leak above.
On Concrete
Usually black or blue-green with a powdery look, often as greenish-black spots with dark borders along the base of a wall. Basement walls, garage floors and slab edges are common, because condensation collects there and the concrete stays cool.
On Clothing and Fabric
Black, brown or green spots, smooth with small bumps and a powdery surface that is actually decaying material. Clothing absorbs and holds moisture from humidity and sweat. Once an item is contaminated it is rarely worth saving, since cleaning one patch leaves the rest seeded.
On Bread and Food
Green or black, fuzzy or smooth, with a musty smell. Bread is damp and full of sugars. Do not cut the mold off and eat the rest, because the growth reaches through the loaf. Store bread somewhere dry and throw out anything affected.
When You Smell It But Cannot See It
Most growth is hidden. It runs behind walls, under floorboards, inside insulation and above ceilings, and the visible patch is the part that finally broke through. A persistent musty smell, allergy symptoms that ease when you leave the house, or paint that keeps bubbling in the same spot are all worth investigating even with nothing to look at. Our guide to where mold grows indoors lists the places worth checking, and what causes mold in a house explains the moisture behind them.
If the growth is flat, powdery and wipes clean off the surface, compare it against our mold versus mildew guide before you worry. Still not sure? Send us a photo on our contact page and we will say whether it needs testing.
Found Something That Looks Like Mold?
Do not scrub it and do not disturb it, because both spread spores. Our IICRC certified technicians identify the growth, trace the moisture feeding it and remove both, and we work directly with insurers. We are available 24/7 across Winnipeg. Call (204) 789-1514 or book an inspection on our contact page.
