Treating Mildew and Mould on Awning Fabric
Mildew is the primary enemy of outdoor fabrics, appearing as unsightly black or green spots. It occurs when an awning is retracted while still damp, creating a dark, moist incubator for spores. While persistent, mildew is often a surface growth that can be removed with patience and the right products.
Safety first: isolate power before touching a motorised system, and never work at height off a ladder alone. If in doubt, book a fitter rather than forcing a mechanism.
Surface debris removal
Before applying any liquid, ensure the fabric is bone dry and use a soft-bristled brush to sweep away loose spores and organic matter. This prevents you from rubbing the dirt deeper into the weave once it gets wet.
The gentle cleaning mix
Avoid bleach at all costs, as it will destroy the UV inhibitors and water-repellent coatings. Instead, use a solution of mild, pH-neutral soap and lukewarm water. Apply it gently and let it soak for several minutes.
- 1Brush off dry debris first
- 2Apply mild soap solution
- 3Agitate gently with a soft brush
- 4Rinse with a garden hose (low pressure)
The 'Bone Dry' rule
The most important part of the process is allowing the fabric to air dry completely while fully extended. Even if it looks dry to the touch, the core of the weave may still be damp. Retracting it too soon will simply restart the mould growth.
Professional deep cleaning
For severe, ingrained staining, a professional valeting service using specialised fabric restorers can often revive a fabric that looks beyond hope, saving you the cost of a full replacement.
Telling mildew apart from other stains
Not every dark mark is mildew. Tree sap leaves a sticky, glossy patch, while general grime tends to be an even grey film across the whole panel rather than distinct spots. Mildew typically appears as small, roughly circular black or dark green dots concentrated along fold lines, since that is where moisture sits longest when the fabric is rolled away.
- Mildew: small dark spots along fold lines
- Sap: sticky, shiny, often under trees
- General grime: even grey film across the panel
- Rust streaks: orange lines from metal fixings
Questions we get asked on repair calls
Can I use a pressure washer?
Never use a pressure washer on awning fabric; it can tear the fibres and strip the protective coatings permanently.
Is mildew covered by warranty?
Typically no, as it is considered a maintenance issue caused by retracting the fabric while wet.
Will mildew come back if I clean it thoroughly?
It can, because microscopic spores are extremely persistent and airborne. Cleaning removes the visible growth, but the fabric will need genuinely dry storage habits going forward or the same damp fold lines will re-colonise within a season.
Is the black staining actually rotting the fabric?
Surface mildew mostly sits on top of the weave rather than breaking down the fibres, but if left for years in a permanently damp environment it can weaken stitching and backing layers, so treating it promptly is worthwhile.
Can I use a household mould spray on awning fabric?
Many household mould sprays contain strong bleach or solvents that strip UV inhibitors from outdoor fabric. Stick to a mild, pH-neutral soap solution and only consider a fabric-specific product if the manufacturer confirms it is suitable for outdoor textiles.
Protecting the coating during treatment
Acrylic fabrics have a lanolin-based water-repellent finish, while PVC-coated fabrics have a plastic top layer; both can be dulled by scrubbing too hard or using hot water. Always work in the direction of the weave with light pressure and rinse thoroughly, since leftover soap residue can attract dirt faster than before.
In short
Mildew is a surface growth caused by moisture; clean with mild soap and ensure total dryness before retracting to prevent it returning.
Get it looked at
Struggling with persistent fabric stains? We can advise on cleaning products or professional valeting.
Ready to Transform Your Outdoor Space?
Get a free, no-obligation quote. Email a photo of the area plus your preferred width, projection and operation type — and we'll do the rest.