Orange mould might look less threatening than the notorious black mould, but make no mistake—it poses its own risks to your home, your health, and your peace of mind. Found both indoors and outdoors, this bright and slimy intruder can signal a bigger problem with moisture and hygiene.
In this post, we’ll explore what orange mould is, why it’s a concern, where it’s commonly found in UK homes, and how to remove and prevent it for good.
What Exactly is Orange Mould?
Orange mould is not one single species but rather a group of fungi or slime moulds that appear orange during their lifecycle. Some of the most common culprits include:
- Fuligo Septica (commonly nicknamed “dog vomit slime mould”)
- Acremonium (a toxic mould species)
- Trichia Varia
- Serratia Marcescens (a type of bacteria often found in bathrooms)
Unlike the fuzzy, powdery moulds we usually imagine, orange mould is usually slimy, lumpy, and wet—making it especially unpleasant to discover on your shower curtain, loft, windowsill, or even your compost heap.
Why is Orange Mould a Problem?
Orange mould may not have the ominous reputation of black mould, but underestimating it could be a costly mistake. It poses several risks that affect both your health and the structural integrity of your property.
Health Risks – It’s Not Just Allergies
Orange mould species vary in severity, but some—like Acremonium—are classified as toxic moulds, producing harmful mycotoxins. Exposure to these spores can affect anyone, not just those with known sensitivities.
In the UK, where we often deal with damp and poorly ventilated properties, especially older homes or converted flats, exposure risks are high.
- Symptoms may include:
- Sneezing and persistent coughing
- Runny or itchy eyes
- Sore throat and sinus congestion
- Fatigue or “brain fog”
- Triggered asthma or breathing issues
- Skin irritation or eczema flare-ups
- Sleep disruption due to mould odour or poor air quality
For vulnerable groups—babies, elderly residents, people with chronic illnesses or respiratory issues—exposure to mould spores can even lead to long-term health complications.
Structural and Property Damage
Orange mould feeds on organic materials, and homes provide the perfect menu: wood, wallpaper paste, plasterboard, food remnants, and even dust. Left untreated, mould will not only keep spreading but also weaken materials, resulting in:
- Rotting or warping of wooden window frames, joists, or floorboards
- Peeling or bubbling paint and wallpaper
- Crumbling plaster and stained ceilings
- Mould contamination in ventilation systems
- Damaged furnishings and textiles (especially in wardrobes or lofts)
In the long run, this can affect home insurance claims, reduce your property’s value, and result in costly repairs—especially if the infestation spreads to hidden areas like insulation or underfloor boards.
Where Does Orange Mould Grow in UK Homes?
Orange mould isn’t picky—it thrives in moist, dark, and poorly ventilated environments, all too common in UK households thanks to our damp climate, single-glazed windows, and often inadequate air circulation.
Indoors Orange Mould
Some of the most common indoor hotspots include:
- Bathrooms: Particularly around silicone sealants, shower curtains, tile grout, and behind toilets or baths.
- Kitchens: Around leaky taps, under-sink cupboards, behind the fridge or dishwasher, and around food bins.
- Window Frames and Sills: Especially wooden or poorly sealed windows prone to condensation.
- Lofts and Attics: Where roof leaks, poor insulation, or lack of ventilation allow moisture to collect.
- Basements and Cellars: Already prone to rising damp or ground moisture—perfect conditions for mould colonisation.
- Air Ducts or Ventilation Units: Mould spores can travel and multiply in HVAC systems, especially if filters are dirty or units are rarely cleaned.
Outdoors Orange Mould
Though often overlooked, your garden or outdoor spaces can also house orange mould:
- Compost bins and heaps
- Mulch and dead leaves
- Wooden decking or fencing
- Sheds and outbuildings with poor insulation
- Potting soil or plant pots, especially in greenhouses
Spores from these outdoor sources can easily be carried indoors through shoes, clothing, pets, or air movement.
How to Identify Orange Mould
Recognising orange mould early is crucial—especially before it spreads out of sight. But because it doesn’t always look like typical “fuzzy” mould, it’s often misidentified as rust, staining, or even spilled food.
1. Visual Clues
- Colour: A bright or burnt orange hue, sometimes turning darker at the edges.
- Texture: Often slimy, wet, or spongy, unlike the dry, dusty appearance of green or black mould.
- Shape: Can look like lumpy patches, foamy growths, or even “vomit-like” splats—hence why slime mould is often nicknamed “dog sick mould”.
- Location: Appears on wood, silicone, plaster, food, damp walls, or anywhere moisture is trapped.
2. Other Signs for Orange Mould
Musty or sour odour: Often the first giveaway of hidden mould, especially in under-sink cupboards, wardrobes, or loft spaces.
Discolouration on paint or wallpaper: Particularly when accompanied by bubbling or peeling.
Recurring condensation: Mould thrives in spots where condensation gathers regularly, such as the bottom corners of windows or cold external walls.
Health symptoms without a clear cause: If someone in your household has new or worsening allergies, it might be a sign mould is present even if not yet visible.
If you spot any signs of orange mould, it’s best to investigate adjacent areas—it’s common for mould to spread behind walls, under flooring, or into insulation materials.
Worth Reading: Types of Mould Colours – Mould Colour Guide
DIY Orange Mould Removal: When and How
Important: If the mould covers more than one square foot or keeps coming back, it’s time to call in professionals. However, for small patches:
Here’s what to do:
- Wear PPE: Gloves, mask, and safety goggles are essential.
- Mix a cleaning solution: Use water, 3% hydrogen peroxide, or an alkaline cleaner (avoid bleach in poorly ventilated spaces).
- Scrub gently: Clean the mould and surrounding area. Avoid spreading spores.
- Dispose properly: Bin any sponges, cloths, or materials used.
- Dry thoroughly: Mould thrives on moisture—ensure the area is dry to prevent recurrence.
Note: Vinegar and bleach-free cleaners also work on food-safe surfaces like chopping boards or bread bins.
Worth Reading: Does Anti Mould Paint Really Work?
Why DIY Isn’t Always Enough
The problem with orange mould is that it often grows beneath the surface, especially in porous materials like wood, plaster, and wallpaper. Even if it seems gone, spores can remain and regrow if moisture returns.
Additionally, aggressive cleaning without the right precautions can spread spores through the air, worsening the problem.
That’s why professionals use:
- HEPA vacuuming and air filtration
- Industrial-strength antimicrobial sprays
- Moisture readings and leak detection
- Safe mould disposal techniques
- Preventative treatment plans
When to Call in the Pros
It’s time to bring in a mould remediation expert if:
- The patch is large, reoccurring, or spreading
- It’s growing on wood or walls
- You or your family are experiencing unexplained health symptoms
- There’s a known leak or high moisture level in your home
Many UK companies offer free or low-cost inspections, and they can also work with your home insurance provider to streamline claims.
How to Prevent Orange Mould in the First Place
Mould prevention is all about moisture control and air circulation. Here’s how to keep your home mould-free:
- Use extractor fans in bathrooms and kitchens
- Wipe down condensation from windows and sills daily
- Dry clothes outdoors or use a vented tumble dryer
- Fix leaks promptly in roofs, pipes, and windows
- Declutter damp-prone spaces like cellars and under-sink cupboards
- Check hidden spots (e.g. behind furniture or inside wardrobes)
Also, treat wooden surfaces with mould-resistant sealants and avoid leaving food waste out in the open.
Final Thoughts: Don’t Ignore That Orange Patch
While orange mould may not seem like a big deal at first glance, it can quickly turn into a health and structural nightmare if left unaddressed. Prompt removal and prevention are key—and in many cases, a professional inspection is the safest way forward.
Don’t wait for the symptoms to worsen or for a small patch to spread across your wall. Whether it’s a slime mould on your garden mulch or an orange stain in your shower, take it seriously and act fast.
If you’re based in the UK and have found orange mould in your home or business, it’s best to seek help from qualified mould remediation specialists. Damp 2 Dry Solutions offers expert mould and damp treatment services across Manchester, Cheshire, Liverpool, Stoke-on-Trent, Chester, and Warrington. Our team is trained to safely inspect, identify, and eliminate all types of mould issues—protecting both your health and your property.
We don’t just treat surface-level symptoms; we address the root cause of damp and mould, ensuring long-term protection and prevention. Whether it’s bathroom mould, rising damp, or loft condensation, Damp 2 Dry Solutions can help.
Visit Damp 2 Dry Solutions to book your free consultation today.