Step Flashing for Roofs at Vertical Sidewalls
Before we can get far into this topic you need to understand the difference between step flashing and continuous flashing. Step flashing is metal flashing, usually galvanized steel but sometimes copper or other metals, and it is normally 10” wide by 7” long. It is bent at a 90 degree angle in the middle of it’s width so that 5” will lay on the roof under the shingles and 5” will turn up the wall to be covered by cap flashing or siding. It is available in larger sizes for specialty shingles. Continuous, “L” , “J “ or “turnback” flashing all look very much like step flashing except they come in 10’ lengths.
Until recently residential building codes have specified the use of step flashing where roof covering meets a vertical sidewall, like at a chimney or dormer. The 2012 International Residential code has now included continuous flashings as acceptable in these areas. The problem is virtually every manufacturer of composition shingles indicates in their installation instructions that step flashing should be used at vertical sidewalls.
The 2012 code is published but it only goes into effect when it is adopted by the code authority having jurisdiction. Most code authorities in the greater Houston area have been allowing (or turning a blind eye) towards continuous flashing for many years even though it has been contrary to code and manufacturer’s instructions.
Here is an excerpt from Sec R905.1 of the 2009 International Residential Code which has been adopted by quite a few jurisdictions. “Roof coverings shall be applied in accordance with the applicable provisions of this section AND the manufacturer’s installation instructions.”
The You Tube video link below demonstrates step flashing installation.
Posted: Oct 7, 2015
Posted by: Ed Fryday, ACI | TREC License: #6932
Space City Inspections, LLC