How to Apply Desmopol — Liquid Polyurethane Waterproofing Membrane

Seamless flat roof overlay & detailing (illustration only)

Desmopol is a high-performance, liquid-applied polyurethane membrane for flat and low-slope roofs, balconies and podiums. Correctly primed and reinforced, it forms a seamless, durable, crack-bridging waterproofing layer with optional UV topcoat and anti-slip finish.

1) Suitable substrates

• Aged bitumen felt/asphalt (sound, firmly bonded)
• Concrete/screed (properly prepared)
• Metal (de-rusted, degreased, primed)
• Plywood/OSB (stable, fixed, primed)
• Selected single-ply refurb (check compatibility; prime accordingly)

2) What you’ll need (map to your listings)

• Desmopol liquid PU membrane (main coats)
• Substrate primer (Desmopol-compatible for bitumen, concrete, metal, timber, etc.)
• Reinforcement fabric/bandage for corners, cracks, changes of plane, penetrations and joints
• UV topcoat (if required by spec/exposure)
• Anti-slip aggregate (walkways/balconies)
• Terminations: PU sealant, termination bar, drip/edge roof trims, outlets
• Prep kit: cleaner/degreaser, rollers/brushes/squeegee, masking, WFT/DFT comb
• PPE: gloves, eye protection, respirator suitable for prep dust/fumes

3) Substrate checks

• Soundness: Remove blisters, loose laps and friable areas; make good.
• Dryness & weather: Substrate must be dry and above dew point; follow temperature/humidity limits.
• Falls & drainage: Clear outlets; mitigate ponding where practical.
• Cleanliness: Degrease, sweep and vacuum; remove poorly adhered mineral granules.

4) Preparation & priming

1. Detail repairs (laps, cracks, voids) and fit trims/outlets as designed.
2. Apply the correct primer for your substrate at stated coverage; allow to dry within the overcoat window.

5) Detail reinforcement (illustration only)

• Stripe-coat Desmopol at corners, upstands, cracks and penetrations; immediately embed reinforcement fabric and wet-out fully.
• Lap reinforcement 50–100 mm; avoid fish-mouths and trapped air.

6) Main membrane application

1. First coat: Apply Desmopol by roller/squeegee to the specified wet-film thickness; work in lanes and back-roll evenly.
2. Second coat: Within the recoat window, cross-roll a second coat to achieve target DFT and continuity.
3. Anti-slip (optional): Broadcast fine/medium aggregate into wet coat for walkways; after cure, de-flute and encapsulate.

7) UV protection & colour

• Apply the specified UV topcoat (colour/finish) where long-term UV stability or colour fastness is required.

8) Terminations & joints

• Seal terminations with PU sealant and/or fix termination bars into chases as designed.
• Do not rigidly bridge movement joints; detail with bandage and compatible sealants.

9) Curing & return to service

• Protect from rain, dust and traffic until cured; respect minimum/maximum overcoat windows.
• Reopen in stages (inspection → light foot traffic → full service) per data sheet and ambient conditions.

10) QA checks & common pitfalls

• Pinholes/holidays: Too thin or porous areas—measure WFT/DFT; re-coat locally.
• Poor adhesion: Usually prep/primer issues—verify compatibility and cleanliness.
• Dew-point/condensation: Causes fish-eyes/blush—check substrate vs. dew point before coating.
• Ponding: Heavy standing water stresses any coating—design for drainage where possible.

Product availability

Desmopol membrane, matched primers, reinforcement fabric, UV topcoat, PU sealants, roof trims/outlets and anti-slip aggregates are available from Clever Shield. Use the site search to find the exact items and sizes for your project.