What is torch on bitumen waterproofing membrane?
Torch-on membrane is a bitumen-based sheet waterproofing system applied by heating the underside of the membrane with a gas torch until it softens, then bonding it directly to the surface below. As it cools, it forms a continuous, tough, water-resistant layer — one of the most established waterproofing methods used on flat roofs, roof decks, and podium slabs across Malaysia.
It’s a proven technology with decades of track record, which is why it remains a default choice for large commercial and residential roofing projects. But it isn’t the only option, and it isn’t always the right one — which is what this comparison is here to help you figure out.
What Is Liquid-Applied Membrane?
Liquid-applied membrane is a waterproofing coating — typically polyurethane or acrylic-based — that’s rolled, brushed, or sprayed directly onto a surface. It cures into a seamless, flexible waterproof layer without any need for heat or open flame.
Because it’s applied wet, it naturally conforms to corners, pipe penetrations, and other awkward details that sheet membranes struggle to wrap around cleanly — making it a common choice for bathrooms, balconies, and retrofit projects.
What is torch on bitumen waterproofing membrane?
Torch-On Membrane vs Liquid-Applied Membrane
Head-to-head comparison to help you choose the right system
| Torch-On Membrane | Liquid-Applied Membrane | |
|---|---|---|
| Application method | Heat-fused sheets | Rolled or sprayed liquid |
| Best surface type | Large, flat, simple areas | Complex or detail-heavy surfaces |
| Flexibility around pipes/corners | Low–Moderate | High |
| Installation safety considerations | Requires open flame — trained applicator essential | No flame required |
| Typical lifespan | 10–20 years | 10–15 years |
| Typical cost | Generally lower per sq ft for large areas | Can be higher per sq ft, but saves labour on detailing |
| Best for | Flat roofs, roof decks, car park decks | Bathrooms, balconies, retrofits, complex detailing |
Many projects use both systems together — torch-on membrane for the main flat area, with liquid-applied membrane around pipe penetrations and detailing. Talk to Chemind about the right combination for your project.
The short answer: for large, flat, structurally simple areas — roofs, decks, car parks — torch-on membrane usually wins on cost-effectiveness and proven durability. For anything with corners, pipes, drains, or irregular shapes — bathrooms, balconies, planter boxes — liquid-applied membrane is typically the better fit because it conforms without seams. Many projects use both: torch-on for the main deck, liquid-applied around the tricky details.
Cost Comparison: Torch-On vs Liquid Membrane
Torch-on membrane is generally the more cost-effective option per square foot for large, uninterrupted areas, since installation is fast once a crew is set up. Liquid-applied membrane can carry a higher material cost per square foot, but often works out more economical overall on smaller or detail-heavy areas, where a sheet membrane would need extensive cutting, patching, and additional labour to seal properly around obstacles.
The real cost driver in both cases is surface preparation — a poorly prepped substrate leads to early failure regardless of which membrane you choose, and redoing a failed job always costs more than doing it right the first time.
The benefits of torch on bitumen waterproofing membrane:-
Torch on bitumen sheet waterproofing membrane is popular among applicators for its strength and more solid membrane base that is created to shield the exterior from dampness and water.
- Easily suite various kinds of flat roof materials , can be used to protect car park decks, green roofing, deck bridge and others.
- Have great resistance towards various weather conditions.
- Bitumen membranes often have high life expectation, even throughout the age it will able to maintain its flexibility and elasticity hence known as the perfect solution for flat roofs.
- Exceptional bond to the substrate on a flat roof installation
- In most general situation where the bitumen membrane system nearing to its life span, a new bitumen sheet can be overlay to install it over the previous system to extend the life service of the system.
Liquid applied waterproofing membrane
Waterproof membrane comes in liquid form, which can be applied with various method such as roller, brush or spray. The liquid will require some time to cure to a solid membrane. After the liquid membrane is applied on the surface it will dries off after a period of time to form a flexible and blocked membrane which protects the screed from water.
The benefits of using liquid membrane
- Seamless application and can be cold applied.
- Can use various application method, using spray gun will increase the speed and also consistency
- UV resistance
- Have high elasticity
- Available in different colours depending on the manufacturer.
SEALOPOL – Bituminious Torch On Waterproofing Membrane
Introducing Chemind Industries’ Sealopol – a high performance polymer modified plastomeric bituminous waterproofing membrane, surfaced with reflective natural colour slates to provide maximum protection against UV. The presence of the slates provides a mechanical protection against light foot traffic and occasional maintenance as well as offering an aesthetic surface. It is an ideal membrane for roofing and exposed applications where it can be placed on top of the existing surface and providing an economical and efficient solution to leaking roofs.
Available in 2 finishing – Slated and Sand with thickness of 3mm in the size of 1 meter x 10 meter per roll.
For other alternative, you can look into self-adhesive bituminous membrane.
When to use bitumen torch on waterproofing?
One of the few popular choice for flat or low-sloped roofing applications where conventional shingles or other materials may not be suitable. This technique is commonly utilized in both commercial and residential construction able to apply different areas such as roofs, decks, balconies, and other surfaces from water damage. In addition, bitumen sheets torch on membrane have longer life spans than other conventional waterproofing methods if applied correctly. It is also ideal for properties located in areas with heavy rainfall or extreme weather conditions.
However the challenges of installing of bitumen torch-on waterproofing requires specialized equipment and skills, and should only be carried out by an experienced waterproofing contractor with expertise in torch-on roofing.
Conclusion
Both materials are specifically to prevent water to enter the substrate and having its own advantages and disadvantages. While torch on membranes offers highly durable and sturdier membrane hence having a longer life span, but it is not a seamless application where if not applied correctly would exposed to possible water penetration through its gap.
Liquid applied waterproofing membrane on the other hand is a seamless application, but may take longer time for application as it requires 2-3 layers of application with a curing time around 2-4 hours depending on the product. As liquid applied waterproofing is not as strong as bitumen sheet membrane, it is more prone to get damaged by external forces.
All in all, it depends on the pros and cons of each of these materials and taking in other factors such as area of application, the substrate and also the applicators experiences in handling these products.
Still unsure which membrane suits your roof, deck, or balcony?
Talk to a Waterproofing SpecialistFrequently Asked Questions
Torch-on membrane is a bitumen-based sheet waterproofing system that's heated with a gas torch and bonded directly to a surface, commonly used on flat roofs and decks.
A trained applicator heats the underside of the membrane sheet with a gas torch until it softens, then presses and rolls it onto the prepared surface, overlapping seams to ensure a continuous waterproof layer.
Neither is universally "better" — torch-on suits large, flat, simple surfaces well, while liquid-applied membrane is usually the stronger choice for complex or detail-heavy areas like bathrooms and balconies.
Torch-on membrane is generally more cost-effective for large flat areas, while liquid-applied membrane can be more economical overall on smaller, detail-heavy areas due to lower labour requirements.
Yes, when installed by a trained applicator following proper safety procedures. The open-flame application does require experienced handling, which is why professional installation matters.
Yes — it's common to use torch-on membrane for the main flat area and liquid-applied membrane around pipe penetrations, upstands, and other complex details.