Torch-on bitumen membrane systems are a highly versatile membrane system. They can be applied in single, double, and even triple layer systems depending on the works & warranty terms required.
A single layer torch-on bitumen system is most commonly found on retaining walls and basements. Some people use a single layer system for planter boxes, we prefer to use a liner as it will last longer and is faster (and less dangerous) to install.
Double layer torch-on bitumen systems are used for retaining walls and basements where an extended warranty is required, or on new concrete roofs where substrate moisture & composition is a known quantity. A double layer torch-on bitumen system is also often used on bridges & in car parks prior to the pouring of asphalt. Many other installers will use two a layer system for balconies or other trafficable areas. It is our experience that torch-on bitumen membranes are unsuitable for these applications as they become extremely soft when warm, and foot prints (especially heels) can pierce the membrane and render it ineffective.
A triple layer torch-on bitumen system is best used in remedial or encapsulation situations where you are waterproofing directly over an existing bitumen membrane system. The first layer of these systems is a venting layer, allowing gasses and moisture to track to drainage points or specific venting points.
Although it is possible to use torch on membranes over timber substrates it is unwise to expose timber to heat and flame, especially in todays market where there are numerous superior alternatives for new buildings and timber constructions.
Torch-on bitumen waterproofing systems are ideal for replacement & encasement of existing failed or damaged bitumen roofs. These can be either traditional hot pour or aged bitumen roofs. This system is also suitable for new concrete constructions where fast turnaround sheet membrane is required. In either two or three layer systems, a system can be developed to suit most works.
Basements & Retaining Walls
From our experience, basements and retaining walls are the natural home of torch-on bitumen waterproofing membranes. In either single or double layer systems, torch-on bitumen provides a tough, long term, highly successful waterproofing solution. This is our preferred system for below ground works.
Like any other below ground membrane, torch-on bitumen waterproofing membranes are only your last line of defence. The membrane must be protected, and good drainage must be provided otherwise there will eventually be trouble.