They can be partially loose laid and held down with river rock ballast requires roof structure to support the weight or fully adhered to the roof deck.
Why put rocks on flat roof.
Membrane roofs are attached in a variety of ways.
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.
Our experience is that most gravel roofs are 3 ply hot mopped asphalt built up with a gravel finish applied.
Rocks are placed on commercial flat roofs for many different reasons if the roof is what is called a ballast roof it is not fastened or adhered down throughout the whole roof.
On many flat roof low slope commercial buildings it s common to see gravel on top of the roof.
Built up roofs or burs also called a tar and gravel roof is a well established and popular style of flat roof that is made up of alternating layers of roofing felt or fiberglass and asphalt that is applied with heat which combine to make a long lasting sturdy roofing system.
Both factors can extend the life of your flat roof.
Pebbles or small rocks spread several inches thick over the outer roof mem.
To weigh down or secure the.
Pros and cons for flat roof materials 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.
The weight provided by the gravel is used to anchor down the roof materials therefore using far fewer fasteners to hold the materials to the decking.
Have you ever wondered why contractors install gravel on flat roofs.
The membrane is.
Gravel is used on flat roofs for two reasons.
In a typical tar and gravel roof which by the way is gradually being supplanted by gravelless roof systems you put down a layer of tar paper then tar and finally gravel.
Specifically there are two main reasons to use a ballasted roof system.
In the summer it gets pretty soft and if left to its own devices would flow to the lowest point on the roof.
The stones force it to stay put.
A flat roof will have several layers of a thin membrane made of tar asphalt and or bitumen material.
Flat roofing is not actually flat.
Tar has a low melting point.
To protect the underlying layer of roofing materials as is the case with built up roofs burs.
It has a very low slope between 1 4 to 1 2 inch per foot so that it drains water.
But such a low slope holds snow and water much longer than a steeply pitched roof and therefore needs a very different material to stay watertight.
This acts as an adhesive when it cools.
Epdm and neoprene roof seams are fastened by adhesive and pvc roof seams are heat or solvent welded.
