Torch-On Membrane vs Liquid Rubber: Which Is Better?

I get this question all the time: “Should I go with torch-on or liquid rubber waterproofing?” Both are excellent systems — but they work differently, and each has its place depending on the roof type and condition.

After decades of fixing leaks across Johannesburg, I’ve used both hundreds of times. I’ve seen where each one shines and where it can fail if used incorrectly. So, in this post, I’ll break down the real differences between torch-on membrane and liquid rubber, using examples from real jobs to help you make the right choice for your home.

What Is Torch-On Membrane Waterproofing?

Torch-on is a bitumen-based waterproofing membrane that’s applied using heat. It comes in rolls — usually 3mm or 4mm thick — and is melted onto the roof with a gas torch, creating a solid, seamless layer that blocks water completely.

It’s one of the most proven systems for flat concrete roofs, balconies, and parapet walls, where long-term durability is essential.

Once installed, we usually coat it with aluminium UV paint to reflect heat and prevent sun damage. When maintained properly, torch-on can last 10–15 years or more.

Learn more about Torch-On Waterproofing Membranes in Johannesburg and why they’re the industry standard for flat roofs.

What Is Liquid Rubber Waterproofing?

Liquid rubber is applied as a liquid and dries into a flexible, rubber-like coating that stretches with the surface. It’s cold-applied (no flames), eco-friendly, and ideal for complex roofs with skylights, vents, or metal sheets.

Because it’s seamless and flexible, it handles movement very well — perfect for metal roofs, IBR sheets, and gutter systems that expand and contract in heat.

We use Liquid Rubber Waterproofing Systems across Johannesburg for both residential and industrial roofs, especially where heat-based application isn’t safe.

Durability and Lifespan

Both systems are durable when installed correctly, but their strengths differ:

• Torch-On Membrane: Extremely resistant to water penetration and UV damage. Ideal for areas exposed to standing water. Lifespan: around 10–15 years.
  
  
• Liquid Rubber: More flexible, easier to repair, and great for roofs that expand and contract often. Lifespan: around 8–12 years, depending on thickness and exposure.
  
  

In one Sandton project, a flat roof with poor drainage held water for days after storms. We used torch-on because it’s designed to handle that kind of ponding. In contrast, for a nearby factory in Midrand with IBR sheeting, we used liquid rubber since the roof moved constantly with heat — torch-on would’ve cracked.

Application and Maintenance

• Torch-On: Requires skilled installation using open flame, precise overlapping, and surface preparation. Maintenance involves recoating the UV layer every few years.
  
  
• Liquid Rubber: Simpler to apply (can be rolled or sprayed), no fire risk, and can easily be recoated for maintenance without removing the old layer.
  
  

If you’re looking for a professional, long-lasting installation, my team handles both systems — including full surface preparation, drainage correction, and post-application testing.

Cost Comparison

Generally, liquid rubber is slightly cheaper upfront, but torch-on offers better long-term protection for heavy-duty surfaces. The final price depends on roof size, condition, and accessibility.

To get a proper comparison, I always recommend a site visit. I’ll assess your roof and explain exactly which system makes sense based on how the structure behaves and how much maintenance you’re willing to do.

When to Use Torch-On Membrane

Choose torch-on when:

• Your roof is flat and concrete-based
  
  
• You need maximum durability and long-term waterproofing
  
  
• There’s a risk of standing or pooling water
  
  
• The area gets full sun exposure
  
  

See examples of where we apply it here: Flat Roof Waterproofing Services .

When to Use Liquid Rubber

Choose liquid rubber when:

• You have a metal roof or IBR sheeting
  
  
• There are lots of details or penetrations (vents, skylights, gutters)
  
  
• You prefer a flameless, eco-friendly solution
  
  
• You want easy maintenance or reapplication in future
  
  

If you’re not sure, I can help you decide. Both systems can be combined — I sometimes use torch-on on the main surface and liquid rubber for edges or skylights where heat can’t reach safely.

Combining Systems for the Best Results

For complex roofs, a hybrid system is often best. I’ve done projects where the main flat roof had a torch-on membrane, while the surrounding metal gutters were sealed with liquid rubber. This approach gives you the strength of bitumen and the flexibility of rubber — the best of both worlds.

This combination works especially well for mixed roofs with both concrete and sheet metal sections, which are common in Johannesburg homes.

Final Thoughts

There’s no “one-size-fits-all” answer. Torch-on is best for heavy-duty flat surfaces and long-term waterproofing. Liquid rubber is perfect for flexible, detailed, or heat-sensitive roofs. The key is understanding how your roof behaves — and choosing the right system for that.

If you’re unsure which waterproofing option is right for your home, I offer free call-outs across most of Johannesburg. I’ll inspect your roof, show you the pros and cons of each method, and give you a clear, honest recommendation.

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