Design Questions

WOULD A MANUFACTURER’S WARRANTY BE TERMINATED DUE TO PONDING?

Ponded water on an EPDM roofing system will not void a manufacturer’s warranty or be the sole reason to deny issuance of a warranty. During the design phase, however, efforts should be made to incorporate positive drainage into the roofing assembly to avoid excessive ponding. It is beneficial to avoid ponding water due to the expense associated with its removal in the event of repairs and also to reduce moisture infiltration and damage in the event of incidental puncture.

REGARDING AGED EPDM MEMBRANE, WHAT TYPE OF SURFACE PREPARATION IS NEEDED TO PERFORM ANY NEEDED REPAIRS?

Because EPDM is a thermal set membrane at the time of installation, no additional curing will occur. Repairs can easily be performed with simple tools and accessories without the need of heavy-duty equipment.

For example, a cut or tear can be repaired by cleaning the membrane surface to remove field dirt (brooming in addition to washing with low sudsing soap and rinsing). The area is then primed and a laminated patch is used to seal the cut or tear.

WHAT TYPES OF IMPROVEMENTS HAVE BEEN MADE TO EPDM SPLICING TECHNOLOGY?

The introduction of membrane splice tapes as an option to the use of liquid adhesives has resulted in less reliability on contractor workmanship, increased production for the contractor, and enhanced performance for the roofing system and building owner.

Laminated components (flashing components that have a pre-applied adhesive tape) have improved flashing quality (an item that has traditionally been problematic).

Equipment utilized to install EPDM single-ply roofing systems has also evolved as well. Innovations have been made to ease the backbreaking work of roof installations – this helps reduce work force fatigue and enhances the installation and performance of the roofing system.

HOW IS EPDM MEMBRANE SPLICED TOGETHER?

Two methods of splicing are currently available using either liquid adhesive or splice tape.

When using liquid adhesive, adjoining sheets are cleaned with the manufacturer’s recommended splice cleaner prior to applying the splicing adhesive. A sealant is used along the edge of the splice and is applied after allowing solvent in the adhesive to flash off (minimum 2 hours). Some manufactures have also used an additional sealant within the overlapping area that is applied immediately before putting the splice together. The sealant is intended as a secondary protection to guard against moist penetration in the event of workmanship error at intersections with factory seams.

The second method of splicing was developed to speed up the seaming processing while maintaining consistent application across the entire seam. This process introduced the use of an adhesive tape in conjunction with a splice primer. The adjoining membranes are primed then the tape is applied once the primer has dried. No additional sealant is used along the edge of the splice. This method has become more favorable due to application consistency.

HOW DOES EPDM PERFORM IN EXPANSION AND CONTRACTION SITUATIONS? SHOULD RELIEF OR CONTROL JOINTS BE UTILIZED THE SAME AS ON A BUILT-UP ROOF?

Relief or control joints are commonly used with built-up roofs to subdivide a larger roof area and segregate possible damage into one small area. EPDM, due to its flexibility (-49 F) and elongation, will accommodate stresses caused by temperature extremes, structural movement, and deflection. In cases where the building is designed with expansion joints, the design should be carried all the way through to the roof and an expansion joint should be incorporated into the roof design.

ARE EPDM MEMBRANE ROOFING ASSEMBLIES FIRE RETARDANT?

An EPDM roofing assembly can be designed to meet Underwriters Laboratories (UL) and Factory Mutual (FM) fire classifications. Like in many other roofing assemblies, the fire retardancy level will depend on roof slope and the various components utilized. Current UL and FM publications contain numerous listings of various approved assemblies.

WHAT ARE THE AVAILABLE THICKNESSES AND TYPES OF EPDM SINGLE-PLY MEMBRANE?

EPDM membrane is manufactured in various thicknesses (.045″ to .090″ thick) and is available as a non-reinforced or reinforced sheet (depending upon application). Other thicknesses are also available for use in non-roofing applications as a special order.

Reinforced membranes contain an internal fabric that is completely encapsulated within the EPDM membrane sheet and is available in various thicknesses (.045″ to .075″). Occasionally, a fleece layer can be added to the underside of the sheet that serves as a built-in underlayment for direct re-roof applications over certain types of existing roofing material.

EPDM is also manufactured as vulcanized (cured) or non-vulcanized (uncured) membrane. Vulcanized membranes have set physical properties due to the vulcanization process and exhibit consistent behavior throughout the sheet that allow the membrane to have memory – this means when the membrane is stretched, it will return to its original state. On the other hand, non-vulcanized EPDM does not have set physical properties because it is not cured when manufactured. This makes the uncured material ideal for use as flashing where the material can be stretched, formed, and shaped.

HOW LONG CAN AN EPDM ROOFING SYSTEM BE WARRANTED?

Generally speaking, system warranties that cover material and labor costs are available; and different manufacturers offer various assemblies with standard warranties that vary from 5 and 10 to 15 and 20 years. In addition, premium coverage up to 30 years is available and can include coverage for higher wind speeds, incidental puncture, and hail resistance.

CAN EPDM BE USED IN INSTALLATIONS OTHER THAN ROOFING?

Yes. EPDM has been used in various installations such as pond liners, tunnels, foundations, thru-wall flashings, terraces, garden roofs, and RV roofs.

CAN EPDM BE COATED OR PAINTED?

Acrylic coatings are available that can be applied directly to a prepared EPDM surface. Preparation usually consists of cleaning the EPDM with a pressure washer and a detergent solution or wash. Latex-based paint products can also be used, however, the EPDM manufacturer should be contacted prior to application to ensure compatibility and continuation of warranty coverage.