I. Common Precautions (to be strictly followed by both)
Base surface treatment is fundamental
The base surface must be flat, solid, and free of debris (remove floating dust, oil stains, and cracks; repair areas with sanding). Otherwise, it may cause hollowing or peeling of the waterproof layer.
The base surface must be dry (moisture content is usually ≤9%, which can be tested by the "plastic film covering method": no condensation on the film after 24 hours of covering). Moisture will reduce adhesion or cause poor curing of coatings.
"Vulnerable parts" such as internal/external corners, pipe roots, and floor drains need arc treatment (plastered into an arc with R=50mm using cement mortar) to avoid cracking caused by stress concentration at right angles.
Environmental conditions must be suitable
Construction temperature: Most materials need to be constructed at 5°C~35°C (see product instructions for details). Low temperatures may cause membrane embrittlement and slow coating curing; high temperatures (≥35°C) may cause coatings to dry too quickly or hot-melt membranes to flow excessively during heating.
Weather: Construction is prohibited on rainy, snowy days, or when winds exceed level 5, to prevent rainwater from washing uncured layers or weak bonding of membranes.
Safety and protection are indispensable
Personal protection: Wear gloves, masks (especially for solvent-based coatings to avoid inhaling volatile substances), and non-slip shoes; for high-altitude operations (e.g., roofs), use safety belts and set up safety nets.
Fire and explosion prevention: Keep away from fire sources during the construction of hot-melt membranes and equip fire extinguishers; open flames are strictly prohibited at construction sites with solvent-based coatings.
II. Specific Precautions for Waterproofing Membrane (Waterproofing Roll) Construction
Preparation before paving
Membranes should be laid flat and unfolded (to avoid curling and wrinkling); polymer membranes need to be protected from direct sunlight (to prevent premature aging); hot-melt membranes should be preheated (but avoid over-baking).
For the cold adhesion method, use matching adhesives (e.g., asphalt adhesives for asphalt membranes, special adhesives for polymer membranes), and apply them evenly (no excessive accumulation or missed coating).
Core operations for paving
Direction: For large-area construction, roof membranes should be paved parallel to the roof ridge; wall membranes should be paved along the long side to reduce the number of joints.
Compaction and air exhaust: Use a scraper to press from the center to both sides to completely expel air (otherwise, hollowing may cause water leakage), ensuring close adhesion between the membrane and the base surface/lower membrane.
Joint treatment (critical):
Hot-melt type: Joints must be fully melted (molten material overflows at the edges) and pressed while hot, with a lap width ≥80mm (for long sides) and ≥100mm (for short sides).
Cold-adhesion type: Apply additional adhesive to joints with a width ≥100mm, press after drying, and finally seal the edges with sealant.
Special parts: For pipe roots and floor drains, first install a "bell-mouthed" additional layer (the membrane wraps the pipe and overlaps with the large-area membrane); the end of the membrane on parapets should turn up ≥250mm, be fixed with press strips, and sealed.
III. Specific Precautions for Waterproofing Coating Construction
Coating preparation and application
Two-component coatings (e.g., polyurethane, JS coatings): Accurately measure and fully stir in proportion (stir for 3~5 minutes until no particles remain) to avoid poor curing due to incorrect proportioning.
One-component coatings (e.g., acrylic coatings): Stir evenly before construction (to prevent sedimentation) to avoid uneven concentration during application.
Application method: Apply thin coats multiple times (usually 2~3 coats). The next coat can only be applied after the previous one is fully cured (4~8 hours, depending on temperature) to avoid cracking from thick one-time coating; adjacent coats should be applied crosswise (e.g., first horizontally, then vertically) to enhance integrity.
Detail reinforcement
Parts such as internal/external corners and pipe roots should first be treated with an additional layer (apply 1~2 separate coats of paint or lay non-woven fabric for reinforcement) with a width ≥200mm to strengthen vulnerable areas.
Curing and protection
Avoid stepping on or watering during the curing period (24~72 hours) to prevent coating damage.
A water tightness test must be conducted after curing (retain water for 24~48 hours; proceed to subsequent construction only if no leakage occurs).
Summary
The key to waterproofing construction is "detail control": For waterproofing membranes, focus on ensuring a flat base surface and tight joint sealing; for waterproofing coatings, ensure uniform application and sufficient curing. Both rely on a dry, clean base surface, suitable environmental conditions, and proper safety protection to achieve long-term waterproofing effectiveness.
