Professional Roofing & Waterproofing Products

The Flash Harry Thermoflex 4mm Waterproofing Membrane (1m x 10m) is a preformed, APP-modified bitumen membrane designed for professional torch-on waterproofing systems. It creates a strong, impermeable barrier that protects buildings and concrete structures against water penetration and long-term moisture damage.

Thermoflex is suitable for concrete roof decks, balconies beneath screeds or tiles, retaining walls, basements, water-retaining structures, planters and flower boxes. Its reinforced construction provides good dimensional stability, strength and resistance to normal movement within properly prepared substrates.

The 4mm membrane is supplied in rolls measuring 1 metre wide by 10 metres long. The manufacturer’s technical information describes the 4mm grade as weighing approximately 4.8kg per square metre, which gives an estimated membrane weight of about 48kg before packaging. Retail listings may show a packaged weight of approximately 52kg.

For the best installation, Thermoflex should be applied over the manufacturer’s compatible solvent-based primer. Flash Harry states that the primer should be allowed approximately three hours to dry before the membrane is installed. Where the membrane remains exposed to sunlight, the manufacturer recommends protecting it with a suitable bituminous aluminium coating rather than an ordinary acrylic roof paint.