Each of the three layers is laid in a half lap system so any joint in the roof is as far away as possible from another joint.
Flat roof felt layers.
Layers of bitumen felt are heat welded onto each other to form an impenetrable barrier.
If you are thinking about refelting a roof or replacing a layer of felt take care that you use the appropriate type of roof felt and adhesive.
Fitted using a blowtorch the 3 layer felt roof system benefits from being more stable than the older methods.
Cover the edges of the roof with strips of felt before laying out the final layer.
1 built up torchon felt system.
Bituminous felt is a form of waterproof sheeting that is used to cover flat roofs or as an underlay beneath slate or tile roofing.
Remove the plies of the flat roof by thrusting into them with a spade.
The hot applied asphalt or coal tar pitch blends with the bitumen soaked roof felt and creates a monolithic roof membrane.
Apply another layer of adhesive to the top for maximum waterproofing.
For many years it was acceptable to put even the third layer.
Asphalt shingles typically can have one more layer added over the top two roofs total.
Built up roofs are installed using several layers of a special type of roofing felt that has been asphalt impregnated and embedded in bitumen applied with a hot mop.
This can include epdm rubber and fibreglass talked about above but commonly especially in the trade and in this article it refers to pvc tpo tpe and pib.
Steep sloped roof products such as tile slate metal and shakes only allow one layer.
Laying down felt on a flat roof is an easy and effective way to improve the strength and durability of an outdoor structure like a garage or shed.
Always stand on a firm section of the roof and wear long pants long sleeves and safety glasses.
Plies are the layers of felts fabrics and mats that make up roofs.
The substance itself is made from bitumen which comes from the distillation of crude oil that has been either mixed with sand or crushed limestone.
You can cover the surface of the felt with gravel for added strength.
Conclusions on felting a flat roof.
The sequence of laying a felt roof is.
Here is a video showing how the felt is installed on the flat roof.
You will follow the same process as in step 2 for the last layer.
On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.
This layer is not bonded to the decking so that the decking can move without damaging the felt roof.
Installing any gutter drips.
In short any roof covering that can make a flat roof waterproof in one layer unlike roofing felt with its 3 layer system for instance.
The 3 layer felt roof system is also versatile when it comes to appearance.
This type of flat roofing felt has been in use for decades and is still used today.
Laying the first nailed layer of underlay felt.
