Frequently Asked Questions

A property developer in Noida is waterproofing the 2,800 square metre flat rooftop of a 12-storey residential tower before application of the ceramic tile protective finish — the roof slab has multiple existing hairline cracks from thermal cycling and the edge parapet wall junction is a known leak point in similar buildings — what is the complete MC-Nafuplan EW waterproofing system specification including substrate preparation, number of coats, parapet treatment, and the protection screed specification to ensure a 10-year leak-free performance?

Flat roof waterproofing of a multi-storey residential tower is a high-consequence operation because any waterproofing failure will cause water ingress into the top-floor apartments, leading to plaster damage, mould growth, and structural deterioration of the RC slab — a defect that is expensive and disruptive to remediate after tiles and screeds are installed. The complete MC-Nafuplan EW waterproofing specification for a 10-year leak-free performance is as follows. Substrate preparation (non-negotiable foundation of system performance): (i) structural cracks — any crack visible to the naked eye (approximately 0.1 mm or wider) must be mapped and sealed before membrane application. Cracks up to 1 mm width: open by angle grinder to a V-groove 5 mm wide x 5 mm deep, clean, prime with MC-Nafuplan EW diluted 1:1 with water as a primer, and fill with MC-Dur 200 or similar flexible polyurethane sealant — allow sealant to cure before applying waterproofing membrane. Cracks from 1 mm to 3 mm width: same V-groove preparation plus embed a 100 mm wide fibreglass mesh tape in the first coat of MC-Nafuplan EW over the crack line before subsequent coats. (ii) Surface repair — remove all loose, friable, or delaminated concrete and repair with MC-Dur 200 trowel-grade mortar flush to the surrounding surface. (iii) Laitance removal — the entire roof slab surface must be shot-blasted or scarified to remove surface laitance (the weak, powdery top layer formed by cement bleed water and fine particles migrating to the surface during concrete finishing) — MC-Nafuplan EW requires a sound, open-textured concrete surface for adequate adhesion; pull-off adhesion of the primer coat must be verified at minimum 0.5 MPa before full membrane application proceeds. (iv) Surface moisture — the concrete must be dry at the surface before applying MC-Nafuplan EW — surface moisture causes adhesion failure and blistering of the bitumen emulsion coating. Do not apply after rainfall until the surface has dried for minimum 24 hours; do not apply if surface moisture content exceeds 4 percent (by CM meter). (v) Penetrations — all roof drain outlets, conduit penetrations, and service pipe penetrations must be cleaned and sealed around with non-shrink cement mortar collars (haunch up the pipe at least 100 mm) before membrane application; rake out and re-seal all movement joints with a suitable joint sealant. Membrane application system — 3-coat specification for 10-year performance: Coat 1 (primer): apply MC-Nafuplan EW diluted 1:2 with water (1 part EW, 2 parts water) by brush to the entire surface at 0.2 to 0.3 kg per square metre (wet) — this diluted coat penetrates the concrete surface and improves adhesion of subsequent full coats; allow to dry minimum 4 hours (touch dry). Coat 2 (base coat): apply MC-Nafuplan EW undiluted by roller or brush at 1.0 to 1.2 kg per square metre (wet); while the coat is still wet, embed a continuous layer of 100 mm wide fibreglass mesh over all movement joints, parapet junctions, and pipe collars — the mesh reinforcement prevents membrane tearing at these high-movement locations; allow to dry minimum 6 hours (touch dry — no black staining on finger). Coat 3 (finish coat): apply MC-Nafuplan EW undiluted at 1.0 to 1.2 kg per square metre (wet); ensure complete coverage with no pinholes or holidays (areas of missed coverage) by inspecting in raking light and touching up any bare spots; total wet film per coat 1.0 to 1.2 kg giving dry film of approximately 0.7 to 0.9 mm per coat — total dry film for 3 coats approximately 2.0 to 2.5 mm. Parapet junction treatment: the parapet wall-to-roof junction is the most critical waterproofing location — 70 percent of all roof leaks in Delhi NCR residential buildings originate at this junction. The waterproofing membrane must be turned up the inside face of the parapet wall to a height of minimum 300 mm above the finished roof level (minimum 150 mm above any ponded water level). The cove fillet (cant strip): form a 40 to 50 mm radius cement mortar cove at the parapet base angle before applying the membrane — a sharp 90-degree angle concentrates strain in the membrane and causes premature cracking. Apply the 3-coat MC-Nafuplan EW system continuously from the horizontal roof surface, up through the cove fillet, and 300 mm up the parapet wall — the continuous cove and upstand treatment eliminates the corner joint that is the principal failure point. Protection screed specification: MC-Nafuplan EW is not UV-stable and must be protected. For a tiled finish: 50 mm reinforced cement screed (M15 grade, 6 mm single bar mesh at 150 mm centres) laid over a polyethylene slip sheet placed over the cured MC-Nafuplan EW membrane — the slip sheet (not bonded to the membrane) allows differential thermal movement between the screed and the waterproofing layer without tearing. Maintain screed-to-parapet gap of 10 to 12 mm filled with polyurethane sealant for movement accommodation. After 28-day screed curing, apply ceramic tile or natural stone in polymer-modified tile adhesive mortar. Flood testing: after membrane application is complete and before screed application, conduct a 24-hour flood test — dam the roof perimeter to 50 mm depth with cement mortar dam, fill with 50 mm of water, mark water level, and check after 24 hours. Any drop in water level indicates a leak; locate and repair before proceeding. Document flood test with photographs for the defect liability period record. Space Arc Engineering supplies MC-Nafuplan EW, MC-Dur 200, MC-Cure curing compounds, and fibreglass mesh reinforcement as a complete flat roof waterproofing system for residential and commercial towers in Noida, Ghaziabad, Delhi NCR, and Uttar Pradesh.