Specifically there are two main reasons to use a ballasted roof system.
Using ballast system on a flat roof.
Roofs with pavers as ballast can be used as outdoor patios.
Fixing and installation options.
Simply put a ballasted roof is easy to install and basically guaranteed maintenance work for a roofer.
Extremely difficult to find a leak in this system since the membrane is well hidden.
Flat roof solar is usually free standing on the roof.
The mounting frames are not secured to the roof and therefore the system has to be weighted down using ballast.
Both factors can extend the life of your flat roof.
A ballasted system adds additional weight to anchor the array to the roof whereas mechanical methods cover two key practises either they penetrate the roof covering and are fixed to the deck or they do not and leave the waterproofing system intact.
Additional benefits of ballast on a flat roof.
It can also be a bit challenging to find a leak with a ballasted roof system and because the stones tend to collect a lot of dirt patching it can be a bit difficult.
Screwing through a flat roof is not good practice as your friends have found out the hard way.
The panels can be mounted east west or south facing or in between depending on roof orientation.
Somebody walking on the roof will undoubtedly step on the ballast and put a hole in the membrane.
Ballast stone traps a lot of dirt making patching difficult.
Holes mean roof leaks and roof leaks mean call the roofer.
Adds a lot of weight to the roof system typically 10 15 pounds per square feet.
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.
The weight on a ballasted roof can be from 10 to 25 pounds per square foot meaning the substructure must be designed specifically to carry more weight than other roofing systems.
Ballasted flat roofs are a popular choice especially for commercial buildings.
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.
Flat roofing is not actually flat.
The easiest way to use flat roofs for photovoltaic systems.
It has a very low slope between 1 4 to 1 2 inch per foot so that it drains water.
Drawbacks of a ballasted roof system.
The s flex roof frame with ballast is the simple and proven solution for non penetrative green roof compatible flat roof installations.
There are pod systems available which are free standing and individually ballasted or you can use a mounting frame and ballast that with slabs.
The gravel can be applied in far less time than using a specially.
A ballast system helps cut roof system application costs as it takes less time to install since sealing the layers together isn t necessary.
A number of attachment and ballast options are available depending on the planned system and the conditions on site.
