The number of plies on a roof implies the number of layers i e.
Flat roof layers.
Adhesive metal straps or gravel are used to secure the rubber roof systems.
It s all about the money.
Plies are the layers of felts fabrics and mats that make up roofs.
However in almost all areas it is not acceptable to install more than two layers of roofing on any commercial building.
Flat roofs are hard to replace some observers suggest it s harder to replace a flat roof than a traditional pitched shingle roof because of the labor required to remove its layers especially on older flat roofs.
Tar and gravel 2.
Bur consists of many layers.
Built up roofing bur was the most common type of flat roof before modified bitumen and membrane roofing were developed.
As the roof is installed more and more layers are added to increase durability and longevity hence the name built up.
The slope of a roof is properly known as its pitch and flat roofs have up to approximately 10.
Rubber is waterproof and is relatively easy to install.
On the plus side.
Why would you want to recover vs tear off.
Modified bitumen is installed in multiple layers multi ply roof each of which is torched to the surface below at every turn of the roll.
Bur systems are redundant meaning if one layer breaks down multiple remaining layers provide immediate protection.
Four plies denotes a four layer flat roof membrane system.
Always stand on a firm section of the roof and wear long pants long sleeves and safety glasses.
Drawbacks include potential leakage at the seams or from product shrinkage.
Flat roofs are an ancient form mostly used in arid climates and allow the roof space to be used as a living space or a living roof.
But now flat roofs often are constructed with fewer layers because of improved waterproofing technology.
Built up roofs are manufactured using built up layers of either tar saturated paper and liquid tar with gravel asphalt rolled asphalt or modified bitumen.
Of course flat roofs are not flat but have a very slight roof pitch of between 1 4 to 1 2 per foot.
These flat roof systems contain one layer of rubber or a rubber type material that is applied without heat.
Modified bitumen an asphalt based multi ply flat roofing system is considered a modern take on its close cousin bur or built up roof.
On most flat roofs such as epdm tpo or modified it is perfectly acceptable to two layers of roofing.
Just enough slope to drain water but also flat enough to be a problem if not constructed properly.