Single-ply membrane

Single-ply membranes offer the widest range of systems in the roofing industry. The three basic systems are ballasted, fuUy adhered, and mechanically fastened. From a cost standpoint, the fuUy adhered system is the most expensive to install, the ballasted system the least. The protected-membrane roofing system can be used with any of the basic systems. The specifications for these systems are pubHshed by the various manufacturers. The following gives a brief description of the roof assembhes. 

Fully Adhered. The substrate, ie, insulation, cover board, etc, that the single-ply membrane is to be attached to is either fuUy adhered or mechanically fastened to the deck. However, there are also appHcations where the membrane is adhered directly to the deck. The membrane is then adhered to the substrate. The typical method for adhering the membrane to the substrate is by applying a contact adhesive to the membrane and substrate, rolling the membrane into place, and brooming once the adhesive is ready. There are one-sided appHcations where the membrane is roUed directly into the adhesive that has been appHed to the substrate only. The membrane used in this appHcation method may be fleece-backed. FuUy adhered systems can be installed on any slope. The fuUy adhered appHcation offers a smooth surface that is easy to maintain and inspect, as weU as exceUent wind resistance on account of positive attachment. 

Mechanically Fastened. The substrate, ie, insulation, cover board, etc, which the single-ply membrane must go over, is typically mechanically fastened to the deck using a low density of fasteners. However, there are also appHcations where the membrane is appUed directly to the deck. The typical... 

The flexible single-ply membranes are manufactured in three forms reinforced, nonreinforced, and fleece-back sheet. 

Polymeric Ma.teria.Is, The single-ply membranes are made from a wide variety of polymers. The following is a brief description of those polymers and their characteristics. There are three thermosetting-type elastomeric membranes as of this writing (1996) neoprene, CSPE, and EPDM. Neoprene is stiU used where oil resistance is needed. Eor instance. Hydrotech uses neoprene flashings, the base of which is hot-set in mbberized asphalt (see ElASTOL RS, SYNTHETIC-POLYCm.OROPRENE). 

Eoss Prevention Data, Mdhered or Mechanically Mttached Single-Ply Membrane Roof Systems 1 —29, Eactory Mutual System, Norwood, Mass. 

Although the material most used for single-ply membranes is EPDM, in competition with it are several other materials— Du Pont s Hypalon (a chlorosulfonated polyethylene), its Neoprene products, and modified PVC. It is believed that future growth in the roofing market will depend on products, such as Hypalon, that are easy to handle and have good ozone resistance, and on PVCs modified with polymeric plasticizers. 

From the first introduction of plastic materials into the roof membrane in Japan and Europe as the sheet (single-ply membrane) or liquid systems, in the late 1950s, they have replaced the conventional hot-applied, built-up bituminous membrane. Single-ply membrane was introduced in USA only in the mid 1960s. 

In Europe, plasticised flexible PVC is the key material used in single ply membranes used to cover large flat roofs. For these applications, plasticiser systems used are mostly linear phthalates (mainly due to their low volatility and high photostability). 

Today, there are many fewer companies involved in the manufacturing of single-ply membranes. The advantages of such systems include speed of installation and no requirement for open flames or heated asphalt. However, they must be installed by properly-trained and manufacturer-approved installers. Most single-ply manufacturers claim that their products have a service life of at least fifteen years. The membranes are formulated to resist UV, heat, bacterial attack, etc. 

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