When it comes to waterproofing a roof, basement, or terrace in Kenya, two application methods dominate the conversation: torch-on membranes and liquid-applied systems. Both can deliver excellent, long-lasting results — but they suit different situations, budgets, and building types. This guide compares the two head-to-head so you can make an informed decision for your specific project.
What Is Torch-On Waterproofing?
Torch-on waterproofing refers to the application of APP bituminous membrane rolls using a gas torch to heat the underside of the membrane until it becomes tacky and bonds to the substrate. Overlapping joints between rolls are heat-welded together, creating a continuous, fully bonded membrane layer once cooled.
What Is Liquid Waterproofing?
Liquid waterproofing involves applying a liquid compound — typically acrylic, polyurethane, or a bitumen-based emulsion — directly onto the surface using a roller, brush, or spray. As the liquid cures, it forms a seamless, flexible waterproof membrane bonded directly to the substrate, without the need for heat or rolled sheet material.
Application Process Compared
Torch-on installation requires specialised equipment (gas torches and cylinders), trained technicians experienced in controlling heat application, and careful attention to overlap widths and weld quality at every joint. Liquid waterproofing, by contrast, can be applied with basic tools — rollers, brushes, or a sprayer — making it faster to mobilise on smaller sites and generally less dependent on specialist equipment, though multiple coats and adequate drying time between them are still essential for a reliable result.
Performance on Complex Detailing
This is where liquid waterproofing has a clear practical advantage. Roofs and terraces with numerous pipe penetrations, uneven surfaces, or intricate corner details are often easier to waterproof with a liquid system, since it can be built up in layers that conform naturally to irregular shapes without needing precisely cut and welded membrane pieces. Torch-on membranes, while excellent on large, open, relatively flat areas, require more skill and additional detailing work — often combined with liquid-applied flashing — around complex junctions.
Durability and Lifespan
Properly installed torch-on APP membranes typically offer excellent long-term durability, often protecting a roof for 10–15 years, particularly on large commercial and industrial roofs. Liquid waterproofing systems, especially polyurethane-based ones, also offer strong durability and — critically — superior flexibility, allowing them to accommodate ongoing thermal movement without cracking, which can be a genuine advantage on roofs or terraces that expand and contract significantly.
Cost Comparison
Material and labour costs vary by brand, thickness, and project size, but as a general pattern, liquid waterproofing systems (particularly acrylic-based ones) tend to be more affordable for smaller residential applications, while torch-on APP membranes often become more cost-effective per square metre on larger commercial roofs, where the efficiency of covering large areas with wide membrane rolls offsets the additional equipment and labour skill required. See our detailed waterproofing pricing guide for Nairobi for specific ranges.
Safety Considerations
Torch-on application involves an open flame, which requires strict fire safety precautions — particularly important on occupied buildings, roofs near combustible materials, or sites with restricted access for gas cylinders. Liquid waterproofing avoids this risk entirely, making it a preferable choice in situations where open-flame work poses genuine safety or insurance concerns, such as roofs adjoining timber structures or occupied residential buildings.
Which Should You Choose?
Choose torch-on APP membranes if: you have a large, relatively open commercial or industrial roof, you need maximum long-term durability at scale, and you’re working with an experienced, properly equipped applicator.
Choose liquid waterproofing if: your roof or surface has complex detailing, penetrations, or an irregular shape; you need to avoid open-flame work near occupied or combustible structures; or you’re waterproofing a smaller residential area such as a balcony or terrace.
Can the Two Systems Be Combined?
Yes — and in practice, this is common. A roof might use a torch-on APP membrane across the main flat deck for durability, combined with liquid-applied detailing at corners, penetrations, and parapet junctions where the flexibility of a liquid system makes installation easier and more reliable. This hybrid approach often delivers the best of both systems.
Frequently Asked Questions
Is liquid waterproofing as durable as torch-on membrane?
Quality liquid systems, particularly polyurethane-based ones, can match or exceed the durability of torch-on membranes in many applications, though large open industrial roofs still often favour APP membranes for cost efficiency at scale.
Can I apply liquid waterproofing myself?
While application tools are simpler, achieving correct coverage, coat thickness, and curing still requires experience — incorrect application is a leading cause of premature failure regardless of how simple the tools appear.
Which system is better for a small residential roof?
For smaller residential roofs, especially with multiple penetrations or complex detailing, liquid waterproofing is often the more practical and cost-effective choice.
Final Thoughts
Neither system is universally “better” — the right choice depends on your roof’s size, shape, usage, and budget. Speak to Catcob Construction Solutions for a site-specific recommendation between torch-on and liquid waterproofing systems.
This article was researched, written, and optimised by Onyonka J.M., a Top SEO specialist and digital content strategist with expertise in the East African market; developing high-quality, search-driven editorial content that enhances online visibility and supports the growth of organisations and industry partners across Kenya and Africa. Learn more about the author.