Installation quality directly affects soundproofing, insulation and waterproofing; key notes from prep to acceptance. Pre-install: measure the opening with a laser level, error ≤ 5 mm, repair irregular openings so deviation < 3 mm; check frames, glass, hardware (hinges, lock points), gaskets and bolts for completeness and damage; avoid installing in wind ≥ 5, rain or on undried walls, and acclimatise profiles on site 24 h if temperature difference is large. During install: centre the frame with wedges, even 10–15 mm gaps, level, mark fix points; expansion bolts ≤ 600 mm apart and ≤ 150 mm from corners with rubber washers, never into brick joints or hollow walls; fill the frame-wall gap with PU foam (continuous, full, no voids), trim, then weather-resistant sealant ≥ 5 mm wide outside and silicone/cement inside; align hinge/lock screws to holes and tighten, checking smooth operation with sash-frame overlap deviation ≤ 1 mm. Post-install: open/close repeatedly for sticking/noise and tight gaskets with no light gaps; spray water 10 min from outside checking indoor leakage (focus corners/joints); measure indoor noise drop ≥ 25 dB versus outdoors; remove protection film promptly (within 48 h or soften with alcohol) and fit guards under sashes. Special scenes: high-rise needs safety frames and harnesses with temporary bracing; french windows need metal corner guards and closer fixing with suction-cup glass lifting. In summary, follow 'precise measurement, standard work, multiple seals, full acceptance'; any omission causes leaks/drafts — use a qualified team and keep records.