Method · Sheet membrane
APP-modified bituminous sheet melted on with a gas torch, laps melted into one. APP copes with heat and UV better than SBS, so it is a common choice for roofs and decks in hot climates like Thailand.
A factory-made bitumen sheet modified with APP plastic, melted onto the substrate with a gas torch. Laps are torched together into one skin.
Roofs and decks in strong heat and sun — APP copes with heat and UV better than SBS, so it is a common choice in hot climates.
Uses an open flame — where hot work is not allowed, choose a self-adhesive sheet. Flashings, edges and penetrations carry the highest fire risk, so a fire watch stays after torching. Every roof gets a water test before handover.
Layers (built up from the bottom)
The underside is melted onto the deck and the laps are torched together. Mineral granules on top protect the sheet.
Applied to the deck so the torched sheet bonds firmly.
Clean, dry concrete, ready for the first layer.
The figure shows one typical build-up. The actual layers are decided after we see the site.
Substrate inspection → primer → sheets torched with overlapped laps → water test → final inspection signed jointly.
Roofs and tanks get a water (ponding) test before handover; the result is signed off jointly.
Sheets are chosen by where they go — roof, below ground or containment. If another one fits better, we will say so.
| Sheet | Strength | Where |
|---|---|---|
| APP (Torch-on)this page | Copes with heat & sun better than SBS — common in hot climates | Roof, deck |
| Self-Adhesive | Easy install, no torch | Foundation, basement wall |
| SBS | Cold-flexible | For cold climates |
| PVC | Widely used on large roofs, easy to install | Roof |
| TPO | Chlorine- and plasticiser-free, recyclable where taken back | Roof |
| HDPE | Resists most acids, alkalis and salts — below ground / containment | Below ground, containment |
| ECB | Cold-flexible, below ground | Below ground |
| EPDM | Rubber with excellent heat, UV & weather resistance; not for oil or solvents | Roof, below ground |
| Bentonite / GCL | Clay sheet, swells with water | Below ground |
Also with this method:South Bangkok Power Station (EGAT)
The area, the state of the substrate (cracks, wet spots, or an old membrane to remove), the system and number of layers, whether it is exposed to the sun, and the hours we can work. Send photos and drawings on LINE and we will check the site and quote.
Where flame is not allowed, a self-adhesive sheet is used instead.
Torch-on is a bituminous sheet melted on with a torch — strong against heat and sun. PVC is a single-ply plastic sheet with hot-air welded seams — widely used on large roofs and able to be mechanically fixed.
Send the roof area, what is on it now and a few photos. We check the site and propose the sheet that fits.
Only want materials? psw-chemical.com ↗TEL +66 2 552 6468 · sales@passawarn.com