Caravans, motorhomes, and campervans stored in the Northern Rivers face one of the most challenging mould environments in Australia. A sealed recreational vehicle sitting unused through the Northern Rivers wet season (November, March) can develop extensive mould throughout its interior in a matter of weeks.
The direct answer: mould in caravans and motorhomes stored in the Northern Rivers is extremely common, often severe, and mostly preventable with the right approach. This guide covers treatment and prevention for stored recreational vehicles in the region’s subtropical climate.
Why Caravans Get Mould So Fast in the Northern Rivers
A caravan or motorhome is essentially a small sealed box with no natural ventilation, significant amounts of fabric and soft furnishings, limited vapour management, and thermal cycling from day-to-night temperature variation. In the Northern Rivers wet season, this creates near-perfect mould conditions:
- Ambient humidity of 80-95% RH outside means the internal humidity builds up to similar levels quickly when the van is sealed
- Temperature variations cause condensation on the cool aluminium, fibreglass, and acrylic surfaces inside
- Soft furnishings (foam mattresses, fabric upholstery, curtains, carpets) absorb moisture from the air and provide ideal mould substrate
- Joinery and cabinetry in caravans is typically lightweight particleboard and MDF, both of which absorb moisture and degrade rapidly when repeatedly wet
- Seals around windows, roof hatches, and joins in the van body degrade with age and UV exposure, allowing rain to enter in ways that aren’t obvious until mould appears
Where Mould Appears in Caravans and Motorhomes
| Location | Why | First Signs |
|---|---|---|
| Mattress and foam cushions | Foam absorbs humidity; direct contact with cold floor/walls | Musty smell, grey-green discolouration on mattress surface |
| Curtains | Fabric hangs against cold window surface with condensation | Speckling along lower edge |
| Ceiling | Warm moist air rises and condenses on cool ceiling surface | Spotting on ceiling lining, particularly above bed |
| Bathroom | No ventilation, concentrated moisture from use | Black speckling on grout, sealant, walls |
| Under-bed storage | Poorly ventilated, cold floor below storage area | Strong musty smell, mould on stored items |
| Cabinetry faces and interiors | Particleboard absorbs moisture; delamination | Swelling of cabinet faces, discolouration inside cupboards |
| Roof vents and skylights | Condensation around seals and fittings | Black staining around vent perimeter |
| External compartments | Open to ambient air, poor drainage | Mould on stored equipment and compartment walls |
Treating Mould in a Caravan or Motorhome
Step 1: Ventilate Before You Start
Open all windows, roof vents, and doors before entering a mouldy caravan and leave them open for at least 30 minutes before spending extended time inside. Use a P2 respirator during cleaning.
Step 2: Remove All Soft Furnishings
Take out mattresses, cushions, curtains, and floor rugs. Assess each outside in daylight:
- Mild surface mould on fabric (speckling that hasn’t penetrated): can often be salvaged by washing in hot water with tea tree oil or a commercial antimicrobial laundry additive, then drying completely in full sun
- Deep mould penetration in foam (smell persists after surface treatment, staining throughout the foam): replace the foam. Foam mattresses with deep mould contamination cannot be effectively treated, the mould has colonised the cell structure of the foam.
Step 3: Treat All Hard Surfaces
Working from ceiling to floor (to avoid re-contaminating cleaned surfaces):
For fibreglass, acrylic, and aluminium surfaces: Apply hydrogen peroxide (3%) or white vinegar by spray. Allow 10 minutes dwell time. Wipe with microfibre cloth. For persistent staining, a commercial caravan surface cleaner or diluted quaternary ammonium solution works well.
For cabinetry (particleboard, MDF): These are the hardest materials to treat effectively because they’re porous. Surface treatment with antimicrobial spray, followed by thorough drying, is appropriate for mild cases. For swollen, delaminating, or deeply moulded cabinetry, the boards need to be replaced, they cannot be dried back to serviceable condition once they’ve absorbed significant moisture.
For the bathroom: Pay particular attention to silicone sealant around the shower and basin. Old, moulded silicone cannot be effectively treated, remove and replace with fresh antimicrobial silicone sealant.
Step 4: Check and Treat the Underbelly and Walls
For severe mould cases, or where the musty smell persists after surface treatment:
- Check the underbelly insulation (usually foam board beneath the van floor), water pooled in the underbelly space can saturate insulation
- Check wall cavities if accessible, some caravan walls have foam insulation that can absorb moisture through seal failures
- Antimicrobial fogging is particularly effective for caravans, a professional fog treatment reaches every surface inside the van in a single treatment, including inside cupboards, under furniture, and into the roof cavity. This is often the most efficient approach for severe whole-interior contamination.
Finding and Fixing Water Ingress
Before the van goes back into storage, find and fix every water entry point. Common leak sources in older caravans:
| Leak Source | Signs | Fix |
|---|---|---|
| Roof sealant cracked | Staining from specific ceiling location | Remove and reapply self-levelling caravan sealant |
| Window seals deteriorated | Condensation inside double-glazed windows; water staining around window frame | Re-seal window perimeter with appropriate sealant |
| Roof vent seals | Staining around roof vent perimeter | Replace vent seal gasket |
| Annexe rail joins | Water entry at the annexe attachment point | Re-seal the rail to van body junction |
| Slide-out seals (motorhomes) | Water entry at slide-out perimeter when extended | Replace slide-out wiper seals |
| External compartment drainage | Water pooling in external storage | Clear drainage holes; add drainage if absent |
Use a hose to test the exterior systematically, one person outside with the hose moving slowly over each potential entry point, one person inside watching for drips.
Prevention: Keeping Your Caravan Mould-Free in Northern Rivers Storage
Preparation Before Storage
- Wash and completely dry all surfaces before closing up
- Wash and dry all soft furnishings, don’t store mattresses or cushions if still slightly damp from use
- Leave cupboards and drawers slightly open to allow air circulation inside the joinery
- Place moisture absorber products (silica gel, DampRid) in enclosed spaces, these help with residual humidity but will not manage a serious moisture load on their own
- Leave roof vents cracked open (use vent covers if rain protection is needed), even a small amount of ventilation dramatically reduces mould incidence compared to a completely sealed van
Active Humidity Control During Storage
Covered storage (carport, shed, or caravan cover) significantly reduces the moisture load on the exterior of the van and reduces the heating from direct sun that drives condensation internally at night.
Dehumidifier: A small mid-capacity dehumidifier with continuous drain capability, placed inside the van, is the most effective prevention for a van stored long-term in the Northern Rivers. A 20 L/day unit on a hygrostat setting of 60% RH, connected to a drain hose running out through a small gap in a window, will prevent mould establishment reliably. The electricity cost for a small dehumidifier is minimal.
Periodic airing: If active dehumidification is not practical, open the van for airing on sunny low-humidity days (mid-winter days in the Northern Rivers are ideal) at least monthly during the storage period.
Mould in Caravans Used as Accommodation
Caravans used as permanent or semi-permanent accommodation on Northern Rivers properties, a common practice in rural and alternative lifestyle communities, face the same mould challenges as any small building in the climate. The treatment principles are the same as for any small structure, and the tenancy provisions (where the caravan is a resident’s primary dwelling) may also apply.
Professional Treatment Options
For severe caravan mould, particularly where soft furnishings are extensively contaminated and the smell is deeply embedded, professional antimicrobial fogging is often the fastest and most complete solution.
A professional fogging treatment for a standard caravan takes 1-2 hours (preparation, treatment, aeration period) and costs approximately $500 to $900 depending on size. For a motorhome, $700 to $1,200. This is often more cost-effective than the time and product cost of thorough DIY treatment, particularly for severe cases.
Frequently Asked Questions
My caravan mattress smells musty even after cleaning. Should I replace it? If the musty smell persists after surface treatment and airing in direct sun, the mould has penetrated the foam core. Foam mattresses with deep mould cannot be effectively treated, replacement is the practical option. Caravan mattresses are available from caravan suppliers and online from $200 to $800 depending on size.
How do I prevent mould when my caravan is in a covered storage facility? The covered storage protects from direct rain but doesn’t prevent ambient humidity from entering the van. Use silica gel or a plug-in dehumidifier on a timer, leave cupboards slightly open, and leave a roof vent cracked with a cover. Check monthly and air out on dry days.
Is caravan mould a health risk? Yes, at elevated levels, particularly for people sleeping in a mouldy caravan. Prolonged exposure to elevated mould spore counts in an enclosed space like a caravan interior can cause respiratory irritation, allergy symptoms, and in severe cases more serious health effects. Treat and prevent it, particularly if the van is used for sleeping.
Can I use bleach to clean caravan mould? Bleach is effective on non-porous surfaces (acrylic, fibreglass, aluminium) and is commonly used for caravan exterior cleaning. For interior surfaces, fabric, foam, cabinetry, it’s not appropriate: it damages fabric, degrades foam, and is ineffective on porous material. Use vinegar, hydrogen peroxide, or tea tree oil for interior surfaces.
What’s the best product for preventive treatment inside a caravan before storage? A borax solution (240 g per 4 litres of water) applied to all hard interior surfaces and allowed to dry in place provides good residual mould inhibition. For surfaces that will contact food or skin, rinse after drying. Alternatively, a professional fogging treatment before storage applies antimicrobial treatment throughout the interior.
Severe mould in your caravan or motorhome in the Northern Rivers? Northern Rivers Mould Removal can put you in touch with an independent local contractor who can fog-treat your caravan or motorhome and get it ready for safe use. Request a quote.