Drawbacks of a ballasted roof system.
Gravel ballasted roof weight.
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.
The gravel used in built up roofing what the roofing contractors were used to was not the same as that used in a ballasted roof.
Ballast stone traps a lot of dirt making patching difficult.
None asphalt roll roofing.
The buildup is ballasted with a gravel layer of at least 50 mm and 80 kg m 2.
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When it comes to estimating the weight of an existing roof field verification of the in place construction is necessary.
A loose ballasted roof where you have 1 to 2 inches of gravel is more on the order of 12 psf.
The weight of roofing constructions above the truss rafter may be estimated with the calculator below.
Ballast tar gravel roofing.
A built up roof for example will typically include the built up membrane itself with or without gravel as well as some kind of insulation and cover board which will vary in thickness from roof to roof.
Ballast is a different style of gravel which is applied to single ply roofing systems.
Roofs with pavers as ballast can be used as outdoor patios.
Extremely difficult to find a leak in this system since the membrane is well hidden.
The gravel can be applied in far less time than using a specially designed screw and plate fastening pattern.
On the other hand ballast roofing might be the right choice for your commercial property if you live somewhere with a ready source of ballast rocks gravel of the appropriate size and you prefer the aesthetic look and texture of the larger stones.
Specifically there are two main reasons to use a ballasted roof system.
Although the primary purpose of ballast is to weigh down the roofing materials it also offers similar protective benefits as described above.
The stones used in ballasted roofing are generally 1 5 2 5 inches in diameter and applied in a thicker layer.
Gravel ballasted roofs with sikaplan or sarnafil single ply membranes are conventionally installed.
Felt tar and gravel roofing 3 ply 4 8 lb m ft 2 23 4 kg m 2 felt tar and gravel roofing 4 ply 5 3 lb m ft 2 25 9 kg m 2.
The single ply membrane and other roof components including thermal insulation are loose laid.
I ve had the same questions i think that the 6 psf range given in many tables is for a multi ply roofing with gravel that is impregnated into the top layer.
