Single Ply Roofing
Single-Ply-membrane-roofing systems (low-slope applications) provide excellent detailing components for roofs with many penetrations. They have the versatility for quality tie-ins to different surfaces, they can be molded to odd shapes, and are also excellent finishes to vertical applications such as walls:
EPDM (Ethylene Propylene Diene Monomer) membrane - also known as rubber - has excellent weathering characteristics because of it durability meaning its ability to stretch and maintain that resilience over a longer period of time when compaired to other single plies giving it the highest capacity of the single plies to resist hail damage on it own merits. EPDM and its components are adhered together with tapes and adhesives. EPDM, traditionally black in color, is now also offered in white. EPDM is manufactured in different membrane thicknesses. A fully-adhered EPDM roofing system installed under the right conditions offer simple long term maintenance care, giving your roof a chance to be serviced well into the future.
TPO (Thermoplastic Polyolefin) & PVC (Polyvinyl-chloride) membranes - also known as plastics - are light colored (typically white, tan or gray) and are known as 'cool roofs' because of their ability to reflect the sunlight reducing the roof’s temperature, thereby reducing heat gains and air conditioning costs. TPO and its components are held together using a combination of adhesives and heat welding. PVC and its components are heat welded together. When supported by rigid coverboards plastics have greater hail resistant qualities. Both plastics (TPO & PVC) are manufactured in different membrane thicknesses.
Roof System Attachments:
Ballasted roofing systems rely on weight installed on top of the membrane to hold the membrane and the insulation below it still and in place. In most cases rock (smooth river worn rock) is the ballast applied over the membrane to weight it down; however, concrete pavers and garden roofs operate under the same principals holding the roofing system down. Ballast is commonly called and or known as “overburden.” Rock ballasted roofing systems are viewed as attractive final surfacings and do offer some solar heat resistance. A ballasted roofing system (using river worn rock) - as a rule – is less expensive than other forms of securing roofing systems to a building because of the natural abundance of natural rock in comparison to the higher cost of manufactured fasteners and adhesives that are used in other roofing system attachments. Although pavers can be installed for pedestrian traffic, ballasted roofing systems are not recommended for roofs with high pedestrian traffic because the membrane is covered and cannot be easily viewed for repairs (without removing the ballast). The weight of ballast can also be a concern; always consult an engineer to have your roof evaluated for weight / load restrictions.
Mechanically Fastened roofing systems rely on fasteners attaching the insulation as well as the single-ply membrane to the roof’s decking to secure it in place. Traditionally, the fasteners used to secure the membrane to the roof's decking are installed in the side-seams of the roofing membrane; those seams are typically 8’ to 12’ apart (the width of the membrane roll) in the roof’s field; with half rolls (4' to 6' wide) installed at the roof’s edges doubling the fastening of the membrane where wind pulls, tests and tears at the roofing system with the most velocity and uplift. Mechanically fastened roofing systems are subjected to wind conditions which at times cause the membrane to flutter stressing the membrane at its attachment points. A recent developement in mechanically-fastened-roof-systems uses the insulation plates (they are used as large washers with the fasteners to secure the board insulation to the roof deck) for a dual purpose. Besides securing the board insulation the insulation plates have been coated so the membrane above it can be heat welded to them from above with heated magnets. This checkering of the membrane’s points of attachment in the roof’s field (6 plates per 4' x 8' board; rather than the traditional 8’ to 12’ seam attachment) greatly reduces the traditional distance between the membrane’s points of attachment further reducing the membrane’s fluttering, which reduces the stress on the membrane's attachment points. Mechanically fastened systems are also considered a less expensive roofing system.
Adhered roofing systems rely on the substrate (the board / surface below the membrane) to be attached to the roof's decking, then the membrane (a single-ply or Built-up-Roofing membrane) is fully adhered (laminated) to that substrate. The substrate could be a smooth concrete deck, plywood, or typically it is an insulation board or other type of coverboard attached to the building's roof deck. For single ply membranes this method of attachment has two outstanding qualities; the membrane – should there be a leak – is easily inspected because there is no ballast/overburden between you and a visual inspection of that membrane; secondly, by the membrane being completely adhered to the substrate the wind can not flutter it about. Aided by walkway pads, walkway pavers, or a rigid coverboard (or a combination of them) pedestrian traffic can be managed in order to protect the roof from damage. A “Fully Adhered” single ply roofing membrane has several excellent qualities; and is considered a mid-ranged priced roofing system.