Membranes roofing systems

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. 

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

In response to the CIB/RILEM recommendations,f RILEM 120-MRS/CIB W.83 Committee on Membrane Roofing Systems, representing 22 coimtries worldwide was formed in 1989. Following the recommendations of its predecessor, the new committee organized two task groups. One, on methods and the other on codes of practice. The purpose of the... 

Thermal Analysis Testing of Roofing Membrane Materials InterimReport of the Thermal Analysis Task Group, RILEM 120-MRSCIB W.83 Joint Conunittee on Membrane Roofing Systems (Sept. 1993)... 

Rossiter, W., Parch, R. M., Flueler, P., Beech, J., Cullen, W., Lobo, O., Oba, K., Puterman, M., Saunders, G., Tanaka, K., Vandewynckel, J., and Bum, S., Thermal Analysis Testing of Roofing Membrane Materials, Final Report of the Thermal Analysis Task Group RILEM 120-MRS/ClB W.83 Joint Coimnittee on Membrane Roofing Systems, p. 68 (Dec. 1, 1995)... 

Common BUR systems ate installed in different ways membrane adhered/attached to deck without insulation insulation adhered/attached to deck with membrane apphed to insulation base sheet adhered/attached to deck, insulation to base sheet, and top membrane to insulation and membrane adhered/attached to deck and insulation apphed over the membrane, the so-called protected-membrane roof... 

Fleece-Back Sheet. A fleece-back sheet is a nonreinforced polymeric membrane that has had a nonwoven mat made of polyester, weighing 101.7—203.4 g/m, laminated to the back of the sheet. The prime use of the fleece-back sheet is in the fully adhered roofing systems. The fleece provides the chemical separator, which eliminates the need for an adhesive that is compatible with the specific membrane or a compatible substrate. 

EPDM is by far the most widely used material in the ballasted roofing system constmction. Because of EPDM s flexibiHty, very large sheets of up to 10,000 square feet (929 m ) can be deHvered to the job site in compact roUs that offer reduced labor on the roof in the seaming process. The typical EPDM sheet size used in ballasted systems is 12 by 30 m and 1.1 mm thick. EPDM is also widely used in both the fully adhered and mechanically fastened roofing systems. In these constmctions, both 1.1- and 1.5-mm thick material is used with widths from 2.1 to 15 m. A majority of the installations use nonreinforced sheet, although reinforced membrane can also be used in all of the system types. The majority of the reinforced sheets go into mechanically fastened systems. 

BP. These nitrile alloy membranes are compounded from PVC, flexibilized by the addition of butadiene—acrylonitrile copolymers, PVC, and other proprietary ingredients. Typically reinforced with polyester scrim, NBP membranes are 1 mm thick and have a width of 1.5 m. They ate ptedominandy used in mechanically fastened roofing systems. NBP membranes exhibit excellent teat and puncture resistance as well as good weatherabihty, and remain flexible at low temperatures. They ate resistant to most chemicals but ate sensitive to aromatic hydrocarbons. The sheet is usually offered in light colors. The physical characteristics of NBP membranes have been described (15). 

The greater portion of PVC is installed in the mechanically fastened roofing system a lesser portion is installed in fully adhered appHcations. Although PVC was once heavily used in ballasted roofing systems, there are only a small number installed in the 1990s. Fleece-back membrane is popular in the PVC constmction for both fully adhered appHcations as well as in appHcations where a separator sheet is needed. PVCs ate resistant to vafious weather conditions, bactefial growth, and industfial chemicals. These membranes ate chemically incompatible with bituminous materials. PVCs ate offered in a variety of colors. The physical characteristics of a PVC membrane have been described (15). 

Nonreinforced. Many nonreinforced elastomeric membranes are available. These allow the roofing system to take full advantage of the elongation, which can be as much as 600%, of the elastomeric membrane. This works to its fullest advantage in handling building movement as well as thermal and other stresses. The nonreinforced membranes are most popular in ballasted roofing systems. 

For rubbers, process oils, which are simply some hydrocarbons, function to plasticise the system (polybutenes are plasticisers in polybutadiene rubber based membranes used for roofing systems). 

---