I. Construction Process for Waterproof Coatings
1. General Construction Flow
Clean the base layer: Remove dust, debris, and hollowed-out areas. Repair cracks and holes (using cement mortar or special repair agents) to ensure the base is flat and solid.
Drying treatment: Solvent-based coatings require the base layer's moisture content to be ≤8%. Water-based coatings (e.g., JS, cement-based) can be applied on slightly damp bases but avoid standing water.
Detail pre-treatment: For pipe roots, internal/external corners, and floor drains, use leak-stopping mortar to create rounded transitions (radius ≥50mm) and apply 1-2 coats of reinforcement layer (width ≥200mm).
Brushing order: First paint vertical surfaces (e.g., walls), then horizontal surfaces (e.g., floors); first apply detail reinforcement layers, then large-area construction.
Brushing methods:
Thin coats, multiple times: Each coat should be no thicker than 1mm. Apply the next coat only after the previous one is surface-dry (no stickiness when touched) to avoid wrinkling or cracking.
Cross-brushing: Apply subsequent coats at a 90° angle to the previous one to ensure uniform coverage without missed areas.
Differences in common coating applications:
Polyurethane coatings: Mix components A and B in proportion, stir evenly before use, and ensure ventilation (solvent-based types have odors).
JS composite coatings: Mix cement-based components with emulsion; can be brushed or scraped, suitable for damp bases, forming a film combining rigidity and elasticity after drying.
Cement-based permeable crystalline coatings: Can be applied by dry powder sprinkling (on damp bases) or slurry brushing, relying on water to penetrate concrete and crystallize internally.
Subsequent construction (e.g., tile laying) can proceed only after the coating is fully cured (usually 24-48 hours, depending on product instructions).
Avoid scratches from sharp objects; use wooden boards for temporary foot traffic if needed.
II. Construction Process for Waterproofing Membranes
1. General Base Layer Preparation
Similar to coatings: The base layer must be flat and clean. Cracks are repaired with sealant, and internal/external corners are rounded (radius ≥50mm).
Special requirements:
Hot-melt method (e.g., SBS membranes): The base layer must be dry; a primer (cold primer oil) can be applied to enhance adhesion.
Wet-laying method (e.g., self-adhesive membranes): The base layer can be damp (no standing water) without drying.
2. Key Steps for Different Laying Methods
Membrane positioning: Unfold the membrane along the chalk line, leaving a lap width (80-100mm for long edges, 100-150mm for short edges).
Hot-melt adhesion: Use a torch to evenly heat the membrane's bottom (asphalt layer) until it melts and turns glossy-black. Quickly press the membrane onto the base layer, using a scraper to expel air for tight bonding.
Lap treatment: Focus on heating lap joints-slightly higher temperature than the membrane itself-so melted asphalt at laps is pressed firmly, with excess hot asphalt extruding to form a sealing strip.
Peel-and-stick: Remove the membrane's bottom release film, align with the chalk line, and press onto the base layer. Use a scraper to press from the center outward to expel air.
Lap treatment: Align lap edges, peel the release film from the upper membrane's lap area, and press firmly with a roller (some products require matching adhesives to enhance laps).
Advantage: No open flame needed, suitable for indoor use (e.g., bathrooms) or flammable environments.
Apply cement slurry: Evenly brush a 2-3mm layer of cement slurry (or special adhesive) on the base layer.
Synchronous laying: Lay the membrane on the unset cement slurry, scrape to bond tightly, leveraging the cured cement slurry's strength for adhesion.
Feature: Applicable to damp bases, ideal for basements, bathrooms, etc.
Membrane placement: Unfold the membrane and fix edges to the base with mechanical nails (or washers) at 300-500mm intervals.
Hot-air welding: Heat and melt lap joints with a heat gun, then weld with a roller (lap width ≥80mm) to form airtight seams.
3. Finishing and Protection
Membrane termination: On vertical surfaces (walls, pipes), membranes should extend upward ≥250mm. Secure terminations with metal strips and seal gaps with sealant.
Protective layer construction:
Roofs and basements require rigid (e.g., fine aggregate concrete) or flexible (e.g., non-woven fabric) protective layers to prevent membrane damage from sunlight or foot traffic.
For bathroom membranes, tiles can be directly laid on top (apply an interface agent to the membrane surface to enhance tile adhesion).
III. Key Construction Precautions
Weather impact:
Coating construction: Avoid rainy or windy days (to prevent coating erosion or sanding). Use low-temperature materials when temperatures are below 5℃.
Membrane construction: Halt hot-melt work in winds ≥5 级 (to prevent fire); for self-adhesive membranes in low temperatures (<10℃), heat the membrane to enhance stickiness.
Detail handling: Corners, pipe roots, and post-cast strips are high-risk areas for leakage-add extra reinforcement (1-2 more coats for coatings, membrane patches ≥300mm wide).
Acceptance criteria:
Coatings: No pinholes, cracks, or bubbles; thickness meets standards (check with a thickness gauge).
Membranes: Flat laying, no hollowing (check by tapping), lap widths comply with requirements, and terminations are sealed.
