The correct process for a built up torch on felt system should comprise of 3 layers one base layer manually fixed to the roof usually nailed followed by one torch on underlay with the top finished with a torch on mineral cap layer.
How to use torch on roofing felt.
Torch on roofing or torch down roofing as it is also known is a flat roof covering solution that involves three layers of modified bitumen felt melt welded onto the roof surface and each other with the use of a blowtorch to create an impenetrable waterproof seal.
There are two different types of torch down roofing systems.
These thick layers of roofing felt are installed by heating the back of the felt with a butane torch and then carefully applying it to the roof.
Two layer and three layer torch down roof systems.
A two layer torch down roof consists of one base sheet and one smooth cap sheet.
You will also find liquid primers.
As it is rolled out the roofing professional will use a torch to heat the bottom of the cap to the top of the base sheet.
At the gutter edge should be what s known as a welted drip edge.
Move the nozzle across the flashing to coat them in an even opaque layer of primer.
In a two layer torch down roof the system is complete at this point.
Use a 4 inch 10 cm paintbrush or a roller to apply the paint or primer.
Installing the roofing felt does take care but can go very quickly.
Apply waterproof paint or primer to promote felt attachment.
Some roofing felts are actually glued down.
Begin at the bottom working in horizontal lines and gradually moving upward.
Drag it gently from one end of the roof to the other east to west or west to east.
A three layer torch down roof features the same base and cap sheets as well as an additional cap sheet with a granulated surface.
Two layer torch down roofing may cost less.
When the two layers are pressed together they form a seal.
These applications are ideal for flat roofs or protective surfaces under roof level decks.