How to Apply Polyurethane Waterproof Coating in Ghana — The Complete Step-by-Step DIY Guide

Polyurethane waterproof coating is one of the few professional waterproofing systems that a competent homeowner can install properly, provided you follow the right process. Skip a step or shortcut the prep, and you’ll be recoating in two years instead of twenty. Do it right, and you get 15–25 years out of one job.

This guide walks you through exactly how we apply polyurethane coating on job sites — the same process, adapted for DIY.

What You’ll Need

Materials

• 10 kg polyurethane waterproof coating (covers ~50 m² single coat, so budget one bucket per 25 m² for two coats)
• Butyl waterproof tape for joints and penetrations
• Flexible crack filler (for any cracks >0.3 mm)
• Wire brush for surface cleaning
• Clean water for washing down the substrate

Tools

• Broad-nose paint roller with 12 mm nap (do not use foam rollers — they leave bubbles)
• 2″ and 4″ brushes for edges and details
• Stir stick (long enough to reach the bottom of the bucket)
• Plastic scraper for removing old coating flakes
• Broom, mop, and squeegee for clean-down
• Bucket for water

Safety

• Nitrile gloves (polyurethane does not wash off skin easily)
• Long sleeves and closed shoes
• Non-slip footwear — wet coating is very slippery
• Eye protection if brushing overhead
• If working on a roof edge, safety harness anchored to the structure

Before You Start: The Weather Rule

Polyurethane coating needs 24–48 hours of dry weather to cure properly after application. Check the forecast. If rain is predicted within 48 hours, postpone. Applying before rain wastes both the coating and your labour.

Best conditions in Ghana:

• Time of day: Early morning (6–10 AM) or late afternoon (3–5 PM). Midday sun makes the coating skin over too fast.
• Temperature: 20–35 °C substrate surface temperature
• Humidity: Below 85% relative humidity
• Season: Dry season (November–March) or a stable dry spell in August

The 7-Step Application Process

Step 1: Clean the Surface

Sweep the entire area thoroughly. Remove all loose debris, dust, and organic matter. Then wash the surface with clean water and let it dry completely — typically 24 hours in Ghanaian conditions. The surface must be:

• Free of dust, oil, grease, and algae
• Dry (moisture content below 5%)
• Sound — no loose or crumbling concrete

Step 2: Remove Any Old Failed Coating

Scrape off any old paint or coating that is peeling, flaking, or lifting from the substrate. Any coating still firmly bonded can be left in place after being roughened with a wire brush. The rule: if you can flick it off with a coin, it needs to come off entirely.

Step 3: Treat Cracks and Joints

Inspect the surface for cracks. For any crack wider than 0.3 mm:

1. Chase the crack with a chisel or grinder to open it slightly
2. Clean out all dust
3. Fill with a flexible crack filler
4. Let cure per the filler manufacturer’s instructions

For construction joints (where two slabs meet, or where the parapet meets the roof), apply a strip of butyl waterproof tape as a bridging layer before coating.

Step 4: Detail the Penetrations

Every vent stack, pipe, drain, and satellite mount is a potential leak point. Wrap a strip of butyl tape around the base of each penetration and dress it onto the surrounding surface. This creates a bridge between the vertical penetration and the horizontal roof.

Step 5: Apply the First Coat

Open the bucket and stir thoroughly for at least 2 minutes with a stir stick. Do not use a mechanical drill mixer — it introduces air bubbles that show up as pinholes in the cured coating.

Apply the coating with a roller in one direction across the whole area. Aim for a wet film thickness of approximately 0.5 mm — that’s about 0.5 kg per m², or 20 m² of coverage per 10 kg bucket for the first coat.

Work from the far corner back toward your exit. Do not walk over your fresh coating.

Between the roller work, use the 2″ or 4″ brush to properly coat edges, corners, and around penetrations. Push coating firmly into every detail area — do not just cover it lightly.

Step 6: Let the First Coat Cure

The first coat needs to reach a tack-free state before the second coat is applied. In Ghanaian conditions (25–30 °C, 60–80% RH), that’s typically 6–12 hours. Check by touching the coating gently — if it doesn’t stick to your finger, it’s ready.

Do not wait longer than 24 hours between coats — after that, the second coat won’t bond as well to the first.

Step 7: Apply the Second Coat

Stir the second bucket thoroughly. Apply the second coat perpendicular to the first — if your first coat was rolled north-south, roll the second coat east-west. This crossing pattern gives you a seamless membrane with no thin spots.

Aim for the same wet film thickness (~0.5 mm). Same brush work at edges and details.

After Application

STAGE	TIME AFTER SECOND COAT
Touch dry	4–6 hours
Rain-resistant	24 hours
Light foot traffic	24 hours
Full water immersion	48–72 hours
Full cure / mechanical properties	7 days

Common Mistakes and How to Avoid Them

• Applying too thin: Trying to stretch the bucket to cover more area gives you an underweight membrane that fails early. Stick to the coverage rate above.
• Skipping the second coat: One-coat systems are 50% of the total dry film thickness — and 30% of the design life.
• Not stirring properly: The heavier components settle to the bottom of the bucket. Un-stirred coating cures unevenly.
• Applying to a damp substrate: The coating won’t bond. Wait for full surface dryness.
• Foam rollers: Introduce air bubbles that show up as pinholes in the cured coating. Use nap rollers only.
• Trapping yourself in a corner: Plan your exit route before you start. Work from far corner back to the exit.

When to Call a Professional Instead

DIY makes sense for simple flat roofs and small areas. Call a pro if:

• Your roof is more than one storey up
• You have complex geometry — lots of parapets, gutters, and penetrations
• There’s a fleece-reinforced system required (parapets, metal gutters, high-movement areas)
• The area is more than 100 m²
• You need a warranty on the workmanship

Buy the Materials

• 10 kg Polyurethane Waterproof Coating
• Butyl Waterproof Tape
• Full range of waterproofing products

Or Book Us to Do It

• Phone: 0555 548 001 or 0241 737 026
• WhatsApp: Chat with us on WhatsApp
• Read next: Top Waterproofing Mistakes to Avoid · 2026 Cost Guide

Festghana Waterproofing Solution Company Limited (trading as Fest Ghana Limited) supplies professional polyurethane waterproof coatings for DIY and contractor use across Ghana. Workmanship warranty on installations.