Contractors lack of knowledge and lack of training.
Residential rubber roof.
On two sides the roof abuts a parapet a short wall common around flat roofs as well as a wall for the third floor.
Here the rubber roof will need to run up the walls and glue to the sheathing.
Most residential rubber roofs are made of single ply epdm synthetic rubber ethylene propylene diene monomer.
To keep water from pooling at these inside corners tom rips 2x4s lengthwise on a 45 degree bevel with a table saw.
To get a quality rubber roof installed it usually has to be done by a commercial roofing company that specializes in flat roofing.
Of all these membrane types epdm synthetic rubber is the most common single ply membrane roof material in both residential and commercial use.
Synthetic single ply roof systems are not the cheapest way to re roof a home in the short term roof material is generally measured by the square which translates to 100 square feet.
The national roofing contractors association provides an overview.
Rubber roofing is likely to cost about 300 or 400 per square while asphalt shingles are usually less than 100 per square.
Rubber roof membranes are often used on flat or low slope buildings including mobile homes or on unusually shaped roofs such as on a dome.