Seamless flat roof overlay & detailing (illustration only)

Mapei Purtop Easy is a cold-applied, liquid polyurethane membrane for flat and low-slope roofs, balconies and podiums. With the correct primer and local reinforcement, it forms a seamless, crack-bridging, UV-resistant waterproof layer. It’s ideal for refurb overlays on felt/asphalt and for complex details around upstands, skylights and penetrations.

1) Where Purtop Easy works best

• Aged, firmly bonded bitumen felt/asphalt (refurb overlays)
• Concrete/screed roofs and gutters after proper preparation
• Metal roofs (de-rusted, degreased, primed)
• Timber decks (stable OSB/ply, securely fixed, primed)
• Complex detailing: upstands, outlets, skylights, plant plinths

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

• Mapei Purtop Easy membrane (main coats)
• Compatible primer matched to the substrate (bitumen/concrete/metal/timber per data sheet)
• Reinforcement fabric/bandage for corners, cracks, changes of plane, joints and penetrations
• UV topcoat/finish if specified by exposure or colour requirements
• Anti-slip aggregate for walkways/balconies (optional)
• Terminations: PU/Hybrid sealant, termination bars, drip/edge roof trims, outlets
• Prep kit: cleaner/degreaser, rollers/brushes/squeegee, masking, wet-film gauge
• PPE: gloves, eye protection, respirator suitable for prep dust/fumes

3) Substrate checks (must pass before coating)

• Soundness: Remove blisters, loose laps and friable areas; make good with compatible repairs.
• Dryness & weather: Apply within temperature/humidity limits; substrate must be dry and above dew point (no condensation).
• Falls & drainage: Ensure outlets are clear; mitigate ponding where practical.
• Cleanliness: Degrease, sweep and vacuum. Remove poorly adhered mineral granules.

4) Preparation & priming

1. Complete local repairs to laps, cracks and voids; re-bed flashings/chases where required. Fit trims/outlets as designed.
2. Apply the correct primer for your substrate at the stated coverage. Allow to dry within the overcoat window.

5) Detail reinforcement (illustration only)

• “Stripe-coat” Purtop Easy at internal/external corners, upstands, cracks and penetrations; immediately embed reinforcement fabric and fully wet-out.
• Lap reinforcement typically 50–100 mm; avoid fish-mouths and trapped air.

6) Main membrane coats

1. First coat: Apply Purtop Easy by roller/brush (or squeegee then back-roll) to the specified wet-film thickness. Work in lanes; avoid puddling.
2. Second coat: After the first coat cures within the recoat window, apply a cross-rolled second coat to achieve the total dry-film thickness.
3. Anti-slip (optional): While the coat is wet (as specified), broadcast fine/medium aggregate to refusal; de-flute and encapsulate with a finishing pass.

7) Terminations & joints

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

8) Curing & return to service

• Protect from rain, dust and traffic until cured. Respect minimum/maximum overcoat windows between coats.
• Re-open in stages (inspection → light foot traffic → full service) per data sheet and ambient conditions.

9) QA checks & common pitfalls

• Pinholes/holidays: Usually from thin application—measure WFT/DFT; re-coat locally.
• Poor adhesion: Typically prep/primer issues—verify cleanliness and correct primer selection.
• Dew-point/condensation: Can cause defects—check substrate vs. dew point before coating.
• Ponding: Heavy standing water stresses any coating—design for drainage where possible.

Product availability

Mapei Purtop Easy, matched primers, reinforcement fabric, compatible sealants, roof trims/outlets and anti-slip aggregates are available from Clever Shield. Use the website search to find the exact items and sizes for your project.