Bur consists of many layers.
Why do they have gravel on flat roofs.
To weigh down or secure the roofing material as is the case with single ply flat roofs.
They tend to have a lifespan of around 20 to 25 years depending the location and the structure of the rest of the property barring any major natural disasters of course.
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 flat roofs or low slope roofs are also commonly found on commercial.
Pros and cons for flat roof materials.
Joists or the supports for your roof may have to be strengthened before application.
I agree with steve c i do have worked with a contractor that does hot and shingle roofing and the gravel has it s purpose there.
However both rubber and asphalt will lose plasticizers and other v.
A bottom layer or two of insulation board multiple intermediate layers of tar or asphalt alternated with layers of roofing felt and a top layer of gravel.
Gravel is used on flat roofs for two reasons.
The benefits of a tar and gravel roof are numerous.
Gravel to protect built up.
Why install a tar gravel roofing system.
All three types of flat roofing cost 250 to 350 per square 100 square feet but prices vary according to region and size of the roof.
Disadvantages of a tar and gravel roof.
A tar and gravel roof is very heavy.
These materials provide the waterproof barrier that contains and sheds the water to protect the roof structure.
Built up roofing bur was the most common type of flat roof before modified bitumen and membrane roofing were developed.
To protect the underlying layer of roofing materials as is the case with built up roofs burs.
A flat roof typically has a rubber or asphalt impregnated membrane.
A tar and gravel roof will generally last around 20 years although if they are well maintained and properly installed this kind of roofing has been known to last almost 40 years.
There are different types and weights of gravel used on flat roofs for these purposes.
Flat roofs usually come with a 10 to 20 year warranty but can last 25 years if you build the roofs right and maintain them using commonsense rules.