(Originally published in the January 2008 Housing Journal)
Code Update Corner
New Code Sections Added for Residential Roofing
On July 27, 2007 the Construction Industries Commission (CIC) approved adoption of the 2006 New Mexico Building Codes that had gone to public hearing earlier in the month. As usual, there is a six-month phase-in of the new codes. Contractors pulling permits from January 1 through June 30, 2008 may choose whether they wish to build to the 2003 or 2006 codes. As of July 1, 2008, all permits must be issued under the new building codes. All of the New Mexico amendments to the codes are available online at http://www.nmhba.org/.
During the code review process there were two issues that were seen as contributing to roof leaks from people walking on flat rooftops for simple tasks like maintaining an evaporative cooler. Both related to items that could cause splits in the waterproof barrier under the roof surface material. One concern was about loose granular fill (usually pumice), and the other was sharp corners of drainage crickets that tear through the roofing paper when workers step on them. The solutions are to require all granular fill be removed during re-roofing, and not allow new applications with granular fill, and to require taperboard (or equivalent) to eliminate sharp corners.
Here are the new sections in the 2008 NM Residential Code:
C. Section R904: See this section of the IRC except add the following new section:
- Section R904.5 Loose Granular Fill. Pumice and other granular fill type materials are not permitted in roof assemblies.
D. Section R905: See this section of the IRC except add the following new sections:
- Section R905.9.4 Roof deck transitions. Add new section of the IRC as follows: Where roof sheathing is overlapped to create drainage “crickets” or valleys to canales, taperboard or equivalent shall be used to transition between the two deck levels to create a uniform substrate.
- Section R905.9.5 Canales and Scuppers. All canales and/or scuppers must have a metal pan lining extending 6 inches minimum past the inside of the parapet and 6 inches minimum to each side of the canale or scupper opening. All canales or scuppers must have positive drainage.
- Section R905.11.4 Modified bitumen roofing. Where roof sheathing is overlapped to create drainage “:cricket” or valleys to canales, taperboard or equivalent shall be used to transition between the two deck levels to create a uniform substrate.
- Section R905.12.4 Thermoset single-ply roofing. Where roof sheathing is overlapped to create drainage “crickets” or valleys to canales, taperboard or equivalent shall be used to transition between the two deck levels to create a uniform substrate.
- Section R905.13.4 Thermoplastic single-ply roofing. Where roof sheathing is overlapped to create drainage “crickets” or valleys to canales, taperboard or equivalent shall be used to transition between the two deck levels to create a uniform substrate.
E. Section R907.3 Re-covering versus replacement. Delete the text of section R907.3 and substitute:
New roof covering shall not be installed without first removing existing roof coverings where any of the following conditions occur:
- Where the existing roof or roof covering is water soaked or has deteriorated to the point that the existing roof or roof covering is not adequate as a base for additional roofing.
- Where the existing roof covering is wood shake, slate, clay, cement or asbestos-cement tile.
- Where the existing roof has two or more applications of any type of roof covering.
- Where pumice or other granular fill are present. Existing roofing and granular fill must be removed prior to re-roofing.