PU & Epoxy Coating Waterproofing

This treatment is specified where the inspection shows it is the right answer for the problem found.

Where it applies. Two different chemistries for two different jobs, and they are frequently confused on quotations. Polyurethane is the flexible, UV-stable choice for exposed horizontal surfaces that move and see sunlight — terraces, podium decks, balconies, metal and RCC roofs. Its value is elongation: it bridges cracks that open and close on a daily thermal cycle. Epoxy is rigid, chemically resistant and not UV-stable — it is for enclosed and immersed conditions: industrial and process floors, bunds, ETP structures, plant rooms, tank linings, and structural crack re-bonding. Epoxy used on an exposed terrace chalks and embrittles within a season or two; PU used in a chemical bund fails to the chemistry. Choosing between them is a specification decision, not a price decision.

Preparation. Both systems are adhesion-dependent, which means the substrate governs the outcome entirely. Concrete is mechanically prepared — grinding, shot-blasting or scarifying — to remove laitance and any previous coating and to open the pore structure to a defined surface profile. Oil and grease contamination on industrial floors is degreased and, where it has penetrated, the affected concrete is cut out. Moisture content is measured before priming, not assumed: both chemistries blister if applied over a slab still releasing vapour, and this is the single most common failure. Cracks are cut out and filled, joints are cut and detailed as joints. The correct primer is applied for the substrate and the moisture condition.

Application. Roller, squeegee or spray depending on the system and the area, in at least two coats, with reinforcing fabric bedded into the first coat at junctions, upstands and penetrations on horizontal work. Mixing is by weight to the manufacturer’s ratio and within the stated pot life — both are two-component systems and an off-ratio or over-worked mix never reaches full cure. Wet film thickness is checked with a comb gauge during application and dry film thickness verified afterwards, because coverage is the specification.

Curing. Touch-dry in 4 to 8 hours and recoatable within a defined window — miss it and the surface needs abrading before the next coat will bond. Light foot traffic at 24 to 48 hours, full mechanical and chemical cure at 7 days. Immersion service and heavy plant loading only after the full 7 days.

Testing and warranty. Adhesion pull-off testing on floor systems, DFT recorded by zone, and flood testing on horizontal waterproofing. Eligible completed work carries Leakproofs by Betterwork’s written ten-year applicator warranty on the treated area, with the specified system and exclusions stated on the estimate.