Frequently Asked Questions

What is the correct application method for MC-Nafuplan on the interior (negative) face of an existing basement wall in Delhi that is experiencing seepage and damp patches, and how many coats should be applied to achieve effective waterproofing?

Applying MC-Nafuplan crystalline waterproofing coating to the negative (interior) face of an existing leaking basement wall in Delhi NCR is the most practical and commonly specified waterproofing approach for existing basements where excavation to the outside (positive) face is impractical — as is the case for the vast majority of the occupied basement car parks and basements in residential and commercial buildings in Ghaziabad, Noida, and Delhi. The negative-side application of crystalline waterproofing is effective because crystalline compounds, once dissolved in the surface pore water, migrate into the concrete by osmosis (water pressure on the outer face drives pore water inward, carrying the dissolved crystalline compounds with it), allowing the waterproofing barrier to grow from the treated interior surface toward the exterior water source. The correct application procedure for MC-Nafuplan on an existing leaking basement wall is as follows. Step 1: Active leak plugging. Before applying MC-Nafuplan, all active leaks (points where water is flowing or dripping through the wall) must be plugged using MC-Bauchemie MC-Stop rapid-setting hydraulic cement. Allow MC-Stop plugs to harden for a minimum of 30 to 60 minutes. Step 2: Surface preparation. Prepare the entire wall and floor surface by mechanical means — wire brushing, scabbling, or pressure washing at 1,500 to 2,000 psi. The objective is to remove all paint, efflorescence, loose mortar, and plaster to expose sound, clean concrete. Any rendering or plaster on the wall must be removed completely — MC-Nafuplan must be applied directly to the concrete surface, not over plaster or render, as crystalline compounds cannot penetrate non-cementitious or heavily painted surfaces. Repair any honeycombing, defects, and cracks wider than 0.5 mm with MC-RocTec 222 repair mortar. Allow repairs to cure for a minimum of 24 hours. Step 3: Dampen the surface. Immediately before applying MC-Nafuplan, thoroughly dampen the entire prepared concrete surface with clean water to achieve a saturated surface dry (SSD) condition — the surface must be uniformly damp but with no standing water or puddles. A dry or partially dry concrete surface will absorb water from the MC-Nafuplan slurry before the coating can be applied uniformly, resulting in rapid stiffening of the slurry and incomplete coverage. In the hot Indian climate, re-dampen the surface immediately before each coat. Step 4: Mix MC-Nafuplan. Add the powder to the specified quantity of clean water (approximately 3.5 to 4.0 litres per 25 kg bag — check the current TDS) and mix thoroughly with a paddle mixer for 3 to 5 minutes to a smooth, lump-free slurry. The slurry should be thick enough to brush onto a vertical surface without running — adjust water dose slightly to achieve this consistency. Mix only the quantity that can be applied within 20 to 30 minutes. Step 5: Apply the first coat. Apply MC-Nafuplan by stiff-bristle brush (a large masonry brush or a scrubbing brush with firm bristles) to the dampened surface, working the slurry vigorously into the surface pores and any surface texture in a uniform coat. Cover the entire wall surface including all corners, construction joints, and the junction between wall and floor. Ensure full, even coverage with no areas of thin application or pinholes. The first coat will immediately begin to grey as the water is absorbed by the concrete — this is normal. Step 6: Apply the second coat. Apply the second coat of MC-Nafuplan after the first coat has reached a leather-hard stage (typically 4 to 6 hours at 25 to 30 degrees C, or up to 12 hours in cooler conditions). Dampen the first coat with clean water before applying the second coat — the second coat must be applied to a damp (not wet) first coat. Apply the second coat perpendicular to the first coat direction (if the first coat was applied horizontally, apply the second coat vertically) to ensure uniform coverage without pinholes or thin spots. For highly demanding waterproofing (deep basements with significant hydrostatic head — water table 3 metres or more above the basement floor), apply a third coat after the second coat has reached the leather-hard stage, following the same procedure. Step 7: Curing. Maintain damp curing of the applied MC-Nafuplan for a minimum of 3 days — cover with wet hessian or damp polyethylene sheeting, or spray with a fine water mist three to four times per day. Do not allow the coating to dry rapidly — premature drying inhibits the crystalline reaction and reduces effectiveness. Do not apply any surface covering (paint, tiles, plaster) for a minimum of 7 days, and ensure the surface remains accessible to moisture vapour from the concrete to allow the crystalline reaction to continue.

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