Metal Flashing’s – The Most Critical Component to Any Roofing System
The roofing system is replete with various types of metal flashing’s. Making certain that all of these flashing’s are in place and not failing is the most critical component to leak prevention and the overall integrity of any roofing system.
Metal is most feasible for use in flashing’s because it is durable and has the ability to be congruent to various shapes, angles and turns. Metal also comes in a variety of colors , or it can be painted to easily match any color scheme.
Essentially, metal flashing’s direct water away from vulnerable points of the roofing system that have the potential of allowing water into and beyond the roof barrier. Without these metal flashing’s water would not be diverted away from these areas and the roofing system would leak. Some of these vulnerable points include roof-to-wall, roof-to-chimney, valley flashing, and other roof protrusions such as bath and kitchen vents. I’ll address a couple of these below.
One of the most common, yet unseen metal flashing’s is the roof-to-wall flashing.
Illustration #1 to the right shows a typical roof-to-wall flashing found on many homes and even some businesses. Another type usually found on brick walls is a counter flashing that covers the step-tins.
Roof-to-wall flashing’s are found on flat and pitched roofs, and can be the most elusive sources of any roof leak. This is because in most instances the flashing (step tins in this picture) are hidden and not easy to inspect for corrosion or other leak sources.
NOTE: because roof-to-wall leaks are against some sort of wall, locating the leak on the opposite side of the source is not an option and usually the individual inspecting the roof has only one option; to remove whatever covers the flashing – in this case siding.
Another common metal flashing is the roof-to-chimney flashing.
The illustration to the right shows a typical roof-to-chimney flashing, although they come in many styles and sizes.
Roof-to-chimney flashing’s are found on flat and pitched roofs and are the number one source of most roof leaks. This is primarily due to poor installation and craftsmanship by the installer. In many cases installers do not implement a cut-in counter flashing technique and simply surface mount the counter flashing; relying totally on caulk to keep water from getting in behind the flashing. As the illustration clearly shows, over the course of couple of years the caulk will break down and the flashing will be rendered useless until replaced.
Valley Flashing is designed to direct water down and away from two interceding roof slopes. Typically manufactured from steel, valley flashing is usually about 20″ wide. Some styles of valley flashing have a “w” or “v” metal diversion incorporated in the center to prevent water from washing down one side of the valley and up the other.