Quick conclusion
The skylight sheet is yellowed, brittle, or leaking without the same cause. Distinguish between aging/dirt on the surface, cracks due to stress–impact, and leaks caused by profile–overlap–screws–drainage. Identify the cause before applying sealant; if deterioration is widespread or safety is compromisedwhole, need to replace the sheet.
Do not fix every defect with glue
| Phenomenon | Reason for inspection | Evidence should be collected |
|---|---|---|
| Yellow/matte | UV aging, dust/chemicals, surface layer, installation surface errors | Both sides photos, clean sample, roof age, UV documentation |
| Brittle/cracked | UV, impact, over-tightening, non-expanding holes, span/load | Crack position relative to screws/support, edge impactbroken |
| Leak | Wrong profile, seam/holes/washer, slope, water pooling, transferposition | Water testing by zone, interior/exterior images |
| Exposed fiber | Surface wear/aging or end-cut processing | Close-up photos, scope, and degree deep |
Sheet yellowed or reduced in light
Clean a small area using a manufacturer-approved method to distinguish surface dirt from material changes. Check UV orientation, film/coating layer, chemicals in emissions, temperature, and usage time. Do not polish or use strong solvents without confirmed compatibility.
Brittle sheets, cracked around screws or broken edges
Cracks radiating from holes often suggest a stress concentration, insufficient expansion gap, over-tightened screws, or constrained displacement. Cracks between spans may be related to impact, load, or material degradation.Possible. The roof area must be isolated and the risk of falling debris assessed before repair.
Leaking roof: tracing the water path
Water can travel far from the entry point to the drip point. Check in order: drainage/slope, overlapping of head and side seams, screw–washer holes, cracks, roof penetrations, gutters, and material junctions. Testing water in zones from low to high helps locate problem spots; do not spray the entire roof from the start.
Controlled handling process
- Prevent access below and above the damaged area.
- Record current condition, weather, roof age, lot number, and maintenance schedule.
- Determine local or system-wide faults through a marked survey.
- Compare drawings, installation instructions, and warranty conditions.
- Choose to repair details, replace individual strips, or replace by area; test water and accept.
When should it be replaced instead of patched?
Replacement should be considered when cracks/brittleness are widespread, the profile does not match, many old holes are torn, the surface has lost its functional capacity, or there is no documentation to prove safety. Local patches do not restore uniform mechanical properties and lifespan to sheets that have comprehensively deteriorated.
Send photos of the whole roof, close-up photos of defects, roof age, product code, leak location, and drawing/profile to receive appropriate screening guidance.
Send documents to receive reportpriceReference sources and limits of use
- ASTM D3841-21: scope of classification, materials, and testing of fiberglass-reinforced polyester panels used in construction; the standard also notes that specific applications may require different performance levels.
- ISO/CIE 10916:2024: procedure to calculate the influence of daylight on building energy performance.
- MCRMA Technical Paper 1: structure, arrangement, and material selection of rooflight for metal roofing systemtype.
- NZ Metal Roofing Manufacturers – Natural Light Materials: compatible with the profile, characteristics, and differences between GRP and Polycarbonate in industrial roofing.
- Nova Construction Products – Rooflight Application Guide: focal point for guiding rooflight and self-drilling screw installation.
Technical limits: This article is used to screen options and prepare quotation data, not to replace construction drawings, structural calculations, light–heat simulations, fire regulations, or specific instructions for the actual roofing system. All thicknesses, spacing, loads, light transmission, fire resistance, durabilityChemicals, warranty, and price must be confirmed with the factory documentation of the shipment before signing the contract or starting construction.
View the product, material, and specification table at guide to choosing Composite/FRP translucent roofing sheets.
Contact Hưng Thịnh Phát for consultation on specifications and pricing at the factory.
