Johns Manville Modified - LeakMaster Roofing and Waterproofing Experts

home > compare flat roofs > johns manville modified

JOHNS MANVILLE MODIFIED* From the manufacturer's website / brochure:

When you purchase a commercial roof from JM, you get far more than just
superior systems and products. We complement the roofing investment with
a variety of unique programs that bring added value to the design, installation,
financing and long-term performance of your roof. Our roofing services include:

• JM Peak Advantage® Guarantees and support
• JM Peak Advantage® Contractor Program
• Systems Engineering Group
• Customer Service
• Life Cycle Management
• CapitalGuard® Roof Financing Program
• JM Roofing Institute™

Our APP modified bitumen products provide high-tensile strength while maintaining critical flexibility. However, through the scientifically advanced
formulation, our APP membranes (coated with a proprietary blend of asphalt and atactic polypropylene) are more compatible with heat-welding application methods. With APP, hot mopping is no longer necessary because the bottom coating may be heated to a point where it acts as its own adhesive, bonding the sheet to a substrate and bonding the overlapping edges. While all our APP membranes are designed to be heat welded, some may also be applied in
cold adhesive. These products have a sand backing in lieu of the burn-off film often found on the heat-welded products. Many of the APP membranes have a
factory-applied mineral surfacing (available in colors) and do not need further protection from harmful UV rays. However, for various purposes, JM also provides smooth-surfaced APP membranes. These membranes must
subsequently be protected from UV rays by applying a compatible roof coating.

Two-ply, heat-welded, modified bitumen, mineral-surfaced roofing system. For use over JM insulation, approved decks or other approved insulations on inclines up to 6 inches per foot (500 mm/m).

* The product information and images above were all resourced from the manufacturer's published information.
For updates and changes visit: www.jm.com

LeakMaster's Opinion

LeakMaster was a leader in switching flat roofs from the dreaded old hot tar kettle to the "torch welded" membrane, commonly known as "Brai." Today, few roofs are torch welded because of insurance regulations. The movement has been towards "self adhered" membranes, also referred to as "peel and stick." Too bad, in my opinion, because the torched roofs worked well. The self adhered roofs have a tendency to unravel at the seams unless great pains are taken. It's safer to use them on roofs that have at least some kind of consistent slope, and don't have ponding water. Hopefully, as the adhesive technology improves this will become less an issue.

In any case, when either system leaks they can be fixed by rewelding the suspect seams. Or, we cover the seams with a fabric reinforced coating and re-granulate them to blend in with rest of the roof. Both ways work well.