Many homeowners have removed aging outdoor decks to find siding, sheathing, and framing that has a texture of oatmeal and a place for carpenter ants. In most cases, the major contributors are worms or missing roof flashing. Without flashing nothing prevents water from oozing behind the ledger board which attaches deck framing to the structure.
Metal flashing materials include lead, aluminum, copper, stainless steel, zinc alloy and other components. Metal flashing is a thin layer of waterproof material that keeps water from migrating into places it should not.
Residential roofing typically is a blend of a multitude of materials and surfaces, whose main function is to create a barrier between the interior and the weather. Water is the most difficult element to control. Roof flashing is the protection against water penetration.
Flashing is used in intersections and terminations on roofing and surfaces to prevent water penetration and usually in areas of valleys, chimneys, roof penetrations, eaves, rakes, skylights, ridges, and roof to wall areas.
Flashing is constructed to combat three systems of water penetrations; gravity, surface tension, and wind pressure. To accomplish this, flashing can be lapped shingle style, soldered or sealed to serve as a continuous surface, or can be constructed with an unbroken profile to breakdown water surface stress.
Roof Flashing materials must be strong, low in up-keep conditions, weather-resistant, able to contain mobility, and be suitable with adjoining materials. A common form of deterioration includes vulnerability to salt air, excessive heat, acid rain, heavy snow, and scouring winds.
Traditional materials and techniques of installing flashing, provide a high building system component. That process requires experience and is very time-consuming.
Many materials can be used for flashing, as long, as it does not scale down in desirability from contact with incompatible materials, and is water-resistant, it should perform.
Centuries ago, carpenters used folded lengths of birch bark to the waterproof intersection of roofs and adjacent walls. There was no water damage, but today builders mostly use these measures:
There are four types of roof flashing, all having important roles in keeping rain from infiltrating into homes and running off elsewhere from the home, working in conjunction with the gutter system. Some homes only need one or two of these roof flashing types, and some homes need all four: