December 2007

Roof area dividers | Technical Elements

Technical Elements not ratednot ratednot ratednot ratednot rated

Roof area dividers

by James R. Kirby, AIA
Be the first to comment

Roof area dividers can perform important functions as parts of roof systems. For example, in regions where there are periods of freeze-thaw cycles, area dividers may be used to relieve thermal stresses on roof systems where expansion joints are not required. Additionally when reroofing is done in stages, area dividers can be used to separate roof system sections that differ in age or type. Area dividers also can be used to isolate a specific area on a roof system, such as damaged materials around an exhaust vent. Detail MB-9A, "Torch-applied Flashing at Area Divider in Roof System" in The NRCA Roofing Manual: Membrane Roof Systems—2007 provides recommendations for proper installation of area dividers.

Detail MB-9A, The NRCA Roofing Manual: Membrane Roof Systems—2007

An area divider consists of a vertical double-wood curb that should be properly anchored to a roof deck. Horizontal wood nailers should be attached to the vertical nailers' base to provide lateral support and a location for attachment to the roof deck. The horizontal nailers should be equal in height to the insulation so a level transition exists from the insulation to the area divider. This allows for a more successful roof membrane installation. An area divider should not be installed on top of insulation; insulation will not provide adequate com­pressive strength to support an area divider.

Similar to all flashing installations, an area divider should extend a minimum of 8 inches above a finished roof system to provide adequate flashing height. Also, NRCA recommends an area divider be covered with a sheet-metal cover. Typically, a sheet-metal cover is attached on an area divider's vertical legs with exposed gasketed fasteners; cleats are needed unless unique...

To read the article in its entirety, please log in or register (registration is free).

Log in or register for FREE access to this article and other Professional Roofing online content.

Not a user?

Register now for free access
  • Full access to every article
  • Online Web exclusive information
  • Photo gallery
  • Breaking news
  • Online classified ads

Already a user?

Log in now

User name:



Login help
Click here to have your user name and password emailed to you.

Comments (0) Login to post a comment or rating
There are no comments posted.