The outdoor special waterproof PU sealant (polyurethane sealant) is a single component, moisture curing, highly elastic, weather resistant and waterproof outdoor sealing material. It is mainly “waterproof+anti-aging+elastic tracking”, suitable for long-term exposure environments such as roofs, exterior walls, windowsills, gutters, expansion joints, etc.
1、 Core performance (essential for outdoor use)
✅ Super waterproof: After curing, it forms a dense elastic layer with a water absorption rate of less than 1%, far superior to ordinary glass glue; Resistant to water pressure and non permeable.
☀️ Weather resistance and aging resistance: -40 ℃~+80 ℃ to keep elasticity; UV resistant, ozone resistant, freeze-thaw resistant, no cracking or powdering for 5-10 years outdoors.
🔄 High elasticity tracking: displacement capability * * ± 25%~± 50% * *, adaptable to thermal expansion and contraction, vibration, without cracking or detachment.
🧱 Universal bonding: Concrete, stone, metal, glass, wood, etc. do not require a primer (except for a few non porous substrates).
🛠️ Simple construction: single component, ready to use after opening the bag, direct injection with glue gun; **-5 ℃~35 ℃ * * can be used for construction, and can be operated on damp surfaces (not exposed to water).
⚠️ Attention: Do not paint after curing (PU is incompatible with paint); It is recommended to use specialized grade for water resistance in areas with long-term waterlogging.
2、 Typical application scenario (outdoor)
Roof/gutter: coil overlap, crack repair, eaves sealing
External wall/window sill: door and window frame filling, parapet wall, expansion joint
Concrete: road/bridge expansion joints, floor slab joints, water/fish ponds
Metal/pipes: rainwater pipes, steel structure joints, ventilation openings
Square/Terrace: Waterproofing of gaps in stone/wood flooring and baseboards
3、 Comparison with other sealants (how to choose outdoors)
PU sealant: elastic ★★★★★, waterproof ★★★★, weather resistant ★★★★, medium to high price; Long term outdoor sealing is preferred.
Silicone weather resistant adhesive: elastic ★★★☆, waterproof ★★★★, weather resistant ★★★★, in price; Dedicated for glass curtain walls, not recommended for floors/roads.
Glass glue (acidic): elastic ★★★, waterproof ★★★, weather resistant ★★, low price; For indoor use, it will crack after 1-2 years outdoors.
Asphalt adhesive: elastic ★★, waterproof ★★★★, weather resistant ★★★, low price; Only for temporary roof repairs, not durable.
4、 Construction points (avoiding water leakage)
Base treatment: clean, dry, and free of oil stains; If the crack width is greater than 5mm, fill the backing strip first.
Glue application: Use a glue gun to evenly apply, compact, and scrape to avoid bubbles.
Curing: Surface drying takes about 2-4 hours, complete curing takes 24-48 hours (slow curing due to high humidity).
Maintenance: Avoid rain and direct sunlight before curing; Achieve optimal intensity in 7 days.
5、 Purchase suggestions
Type selection: Choose outdoor specific/weather resistant PU, prioritize single component, black (best UV resistance).
Check the parameters: displacement capacity * * ≥ ± 25%, elongation at break ≥ 300%, no brittle fracture at -40 ℃ * *.
Brand recommendation: Domestic (Puseda, Keyao, Dongfang Yuhong); International (Sika, Dow Corning).
Avoiding pitfalls: Careful selection of “PU+silicone mixed adhesive”, unstable performance; Materials priced below 10 yuan per unit are often of poor quality and prone to aging and water leakage.