01/12/2011

Getting the Edge on Roofing

By Richard L. Fricklas

 
  • Getting the Edge on Roofing

    Getting the Edge on Roofing

    /Portals/1/images/OnlineImages/0111/B_0111_RN_EdgeonRoofing1.jpg

    Roofing manuals may contain drawings showing roof edge metal systems, but invariably, they admit that the detail “will require more than average maintenance.”
    Photo courtesy of NRCA. View larger

    Getting the Edge on Roofing
  • Getting the Edge on Roofing

    Getting the Edge on Roofing

    /Portals/1/images/OnlineImages/0111/B_0111_RN_EdgeonRoofing2.jpg

    Stripping plies tend to crack, especially if a metal cap is used to join fascia edging together. Walk the building’s perimeter and visually examine the fascia material to determine whether your building has this problem.
    Photo by Dick Fricklas.

    Getting the Edge on Roofing
  • Getting the Edge on Roofing

    Getting the Edge on Roofing

    /Portals/1/images/OnlineImages/0111/B_0111_RN_EdgeonRoofing2a.jpg

    This is the typical sequence of installing the roof membrane, embedded metal, and stripping plies.
    Photo courtesy of RIEI.

    Getting the Edge on Roofing
  • Getting the Edge on Roofing

    Getting the Edge on Roofing

    /Portals/1/images/OnlineImages/0111/B_0111_RN_EdgeonRoofing3.jpg

    Flashing membrane, which is tougher and more flexible than the roof membrane itself, helps ward off the need to remove torn stripping plies and replace them again and again. The flange of the metal fascia is placed on top of the installed membrane instead of being sandwiched.
    Photo courtesy of Metal Era.View larger

    Getting the Edge on Roofing

In the art of designing low-slope membrane roofing systems, the industry has been bogged down by troublesome details that require frequent repair. The most egregious of these are metal roof edge details.

While we boast about 20- or 30-year warranties for our roof systems, we carefully exclude the ubiquitous gravel stop edges from the warranty. One reason for this is that roofing material manufacturers in general don’t produce or market the roof edge metal systems. While manufacturers’ roofing manuals may contain drawings showing such features, there is invariably a disclaimer, such as “This detail will require more than average maintenance.” According to the National Roofing Contractors Association (NRCA), it’s best to avoid flashing details that require rigid metal flanges to be embedded or sandwiched into the roof membrane whenever possible.

One “fix” that is sometimes recommended is elevating the gravel stop edge above the plane of the roof and pitching roof water away from the building edge towards interior roof drains. This won’t solve the metal movement and consequential splitting of the stripping plies, but at least water is not running into the splits, which rots the supporting wood nailers and eventually leaks into the building interior.

The typical sequence involves installing the roof membrane and embedded metal and topping it with stripping plies. In the real world, these stripping plies crack, especially if a metal cap is used to join fascia edging together. Just walking the perimeter of a building and visually examining the fascia metal will let you know if there is such a problem.

When metal is embedded, the edge metal also serves as a gravel stop, so it will be necessary to spud (chip) back the gravel, remove the torn stripping plies, and install new stripping, consisting either of ply felts, glass mesh, or (more recently) modified bitumen. After a couple of years, we can expect to do this again and again.

This is helped somewhat when flashing membrane –  something more flexible and tougher than the roof membrane itself – covers the roofing plies and extends down the exterior blocking. The flange of the metal fascia is placed on top of the installed membrane, rather than being sandwiched. This flexible flashing at least achieves the goal of directing the water to the outside the building instead of the interior.


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Visit our website today to learn about the design flexibility of a Morton building and the endless possibilities of partnering with our designBUILD team.


Wood construction is both cost and energy efficient. Check out Morton Buildings and our designBUILD team online today to discover all the benefits of post-frame construction.


When choosing a metal-clad building for your next construction project, consider Morton Buildings, Inc., and their designBUILD team, we’ll make your dream a reality.

We Can Help You Reduce Energy by 30%

Our mission is to help our customers manage their buildings' energy costs, improve reliability, and enhance performance while having a positive impact on the environment.
CLICK HERE to find out how.

 

Add highly responsive multi-zone comfort to any building project, in any climate. Our CITY MULTI H2i R2- and Y-Series VRF systems give you flexibility to fit the needs of any building. Enjoy 100% heating capacity at 0°F outdoor ambient, and 85% heating capacity at -13°F outdoor ambient.  For more information, log on to www.mitsubishipro.com

 


Tennant Company is a recognized leader in designing, manufacturing and marketing solutions that help create a cleaner, safer, healthier world. With thousands of satisfied customers already using award winning ec-H2O technology, why not see what you're missing? Test ec-H2O on your soils in your facility. Get a free demo.


Tennant Company is a recognized leader in designing, manufacturing and marketing solutions that help create a cleaner, safer, healthier world. With thousands of satisfied customers already using award winning ec-H2O technology, why not see what you're missing? Test ec-H2O on your soils in your facility. Get a free demo.

 

Replace core drilling with Connectrac In-Carpet and On-Floor Wireways, the proven connectivity solution in open interior spaces of all kinds. These elegant low-profile wireways are great for AV / telecom connectivity wherever it’s needed.

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