Ballasted Roofing System
A ballasted roof means that the roof membrane is not anchored or adhered in any way to the decking material. It is, however, ballasted, generally with gravel. The stones used in ballasted roofing are generally 1.5 – 2.5 inches in diameter and applied in a thicker layer. The stones are therefore much more substantial and hold up well under wind tunnel tests.
Ballasted systems are primarily used for large new construction projects, but can also be used on roof replacement or recovery projects where the existing structure can support the additional weight. Ballasted systems are traditionally the easiest of all systems to install and have earned the Underwriters Laboratories Class A rating.
In many cases, ballasted roofing also uses pavers in places of heavy traffic or even over the entire surface of the roof. In fact, the weight of the stone “ballast” is the only item holding the roof components in place. The weight can vary from 10 pounds per square foot (the minimum allowed by code) to 25 pounds or more.
Paver ballast can come in a several forms. Concrete and rubber pavers are two common choices. Concrete pavers are an attractive and functional choice for plaza decks, terraces or part of an integrated roof garden assembly.
With ballasted plaza paver systems and a wide variety of vegetated roof garden options, not only can you create a cool roof that helps reduce energy usage, but you can also create an aesthetically pleasing, usable space on the rooftop. By combining river-washed stone ballast, concrete architectural pavers, interlocking rubber pavers and rooftop vegetation, a flat, non-usable surface can be transformed into a multifunctional plaza with numerous benefits, including:
- Improved stormwater management
- Increased air and water purification
- Superior sound insulation
- Energy efficiency
- Beautiful, usable building space
- Possible federal, state and local tax incentives
- Significantly extended roof life
Because a ballasted system is loose-laid, with plate and fasteners installed here and there to prevent excess movement, the installation is extremely simple and quick. It also has the advantage of being able to be installed during almost any kind of weather and temperature conditions. Since there are no fasteners, and no need for heat or sticking materials, there is less clutter and no smell during installation. In addition, the stones or pavers and virtually fireproof, making this one of the most fire resistant roofing systems on the market.
Ballasted roofs are durable and long lasting. The roof tends to flex a little better under the expansion and contraction of heat and cold, making it a bit more durable. Stones or concrete pavers protect the waterproofing layer from UV rays, hail, and foot traffic. The loose-laid layers in a ballasted roofing system are easily taken up making for easy repair. And at the end of the roof’s designed lifespan, the lack of adhesives allows the roof to be totally recycled.
- Non-reinforced membrane
- Acceptable Insulation
- Approved Roof Deck