Car Wash Waterproofing in Ghana 2026: Bays, Sumps & Office Walls
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A car wash needs waterproofing in four places: the bay floor, the splash walls, the sump or interceptor pit, and any rooms next to or below the bay. Polyurethane is right for walls and as a membrane under a protective finish, but not as the exposed surface of a bay where vehicles turn on it. Below-ground sumps need crystalline cementitious treatment first, because water pushes in from the soil side.
Why car washes are hard on buildings
Most buildings get wet when it rains. A car wash is wet all day. Pressure washers drive water into joints, detergents break down weak sealants, sand and grit abrade every surface, and the sump sits in saturated ground. Add Accra's heat and UV — surfaces reach 75°C on exposed slabs — and ordinary paint-on solutions fail quickly.
Area by area
| Area | Problem | Recommended approach |
|---|---|---|
| Wash bay floor | Constant water, tyre wear, detergents | Membrane under screed or tiles, or a vehicle-rated system; falls to channel |
| Splash walls | Spray penetrates blockwork and render | 2-coat PU upstand; tiles or cladding over in heavy-spray zones |
| Drainage channel | Joint leaks into subgrade | Fleece-reinforced PU lining at joints and corners |
| Sump / interceptor pit | Groundwater from outside; oily water inside | Crystalline cementitious + PU top-coat |
| Office, shop or storeroom next door | Damp and mould in the shared wall | Treat the wet side; do not rely on painting the dry side |
| Canopy roof | Normal rain exposure | Standard roof system |
The bay floor: be realistic about coatings
We sell polyurethane coating, and we will still tell you not to use it as the top surface of a car wash bay. A thin elastic membrane is excellent at keeping water out; it is not designed to take a car turning its wheels on it all day with sand underneath. Specify it as the waterproof layer, then protect it with a bonded screed or tiles with sealed joints. The bay itself should fall toward the drainage channel so water never sits.
Sumps and interceptors: negative-side work
A sump below ground is pushed on from outside by groundwater, especially in the rains. A coating on the inside face alone can be lifted off by that pressure. On our Kasoa filling station sump pit we used a crystalline cementitious treatment, which reacts inside the concrete pores, and then a polyurethane top-coat. For an active leak through a hole or tie-bar, Plugging King (GHS 100) seals the point first because it sets under running water. See positive vs negative-side waterproofing.
Splash walls
Carry the membrane at least 300 mm up every wall that touches the bay, and higher where the pressure washer reaches. Where staff aim spray at walls, cover the membrane with tiles or cladding. Around fixings and hose reels, treat each bolt as a penetration.
Costs and quantities
- 2-coat polyurethane: GHS 80-130/m² installed.
- Fleece-reinforced (channels, joints, corners): GHS 180-280/m² for those areas only.
- Material: about 0.4 kg/m² across two coats. 10kg (GHS 1,000): 40-80 m² per coat, 20-40 m² finished. 5kg (GHS 500): 20-40 m² per coat, 10-20 m² finished.
A two-bay facility with 80 m² of floor and 40 m² of splash wall needs about 48 kg of membrane before protective finishes.
Plan the work around trading
Owners lose money every day a bay is shut. Work can be phased one bay at a time, and polyurethane is usually walkable within about 24 hours, but a screed or tiles over it adds curing time before vehicles return. Agree the phasing before work starts.
Warranty and design life
3-year workmanship warranty, 3-year manufacturer material warranty, 20-year design life for the membrane. The warranty is the period we return and fix it at our cost; the design life is how long the membrane is engineered to keep performing. The protective finish over the bay — tiles or screed — is a separate wearing layer and should be maintained as one.
Get a site survey
We survey bays, sumps and adjoining rooms and give a phased programme so you can keep washing. Book an inspection or call 0555 548 001.