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April 27, 2018

Understanding Metal Roof Flashing and Its Usefulness

When it comes to a leaky roof, no one can disagree how inconveniencing and potentially damaging it can be. The good news is that with proper flashing, you can avoid all that.

Metal roof flashing is basically an installation that keeps water from seeping into your structure either through joints or at roof penetrations. You can get flashing made of different kind of materials, but metal is preferred due to its durability and flexibility. With good flashing, you can get the best line of defense against water percolation into your interiors.

What is Flashing?

Flashing systems are installed at terminations and intersections between surfaces and roofing systems. They are designed to keep water from percolating through areas where there is roof discontinuity.

Metal flashings come in thin pieces and are installed at strategic junctures on a roofing system to give you an envelop that is weather resistant. You can typically find flashings around skylights and at the bases of chimneys. This is because the installation of skylights and chimneys involves cutting holes on the roof.

Without flashing, it becomes extremely difficult to seal the hole up thereby leaving the intersections to expand and contract periodically in response to changes in humidity and temperature. With proper metal flashing installation, you can keep your intersections completely sealed while at the same time allowing for the expansion and contraction movements.

Flashing keeps water out of your roofing through gravity, wind pressure, and surface tension. There are various ways flashing can be installed on your roof. One piece can overlap another or can be reconfigured with a non-continuous profile that prevents water from penetrating your interiors through surface tension.

The Importance of Flashing

Over the years, people have tried all means to keep water away from their interiors and air movement in check. However, most of these efforts have not yielded the results they have been anticipating and instead ending up with drafty structures that are not energy efficient.

Some of the techniques tried out include placing chimneys at the roof ridge, angling roof shingles away from the joint, and building steps into the chimney sides to assist in throwing off water.

Because the above methods proved unsuccessful, flashing was developed to take care of their deficiencies. Vent pipes, chimneys, door and window openings have all benefited immensely from flashing installations.

The beauty with preventing penetration of water into the interiors is that it also stops mold growth. Most of the buildings with flashing systems installed have displayed structural durability.

Common Flashing Materials

Flashing materials are diverse from rubberised asphalt and plastic to metallic materials. You can decide to either conceal or expose your flashing materials. Typically, metal flashing is exposed, but you can also have it installed under some outer covering or shingles.

Among the metallic materials used in flashing include lead, copper, lead-coated copper, aluminium, stainless steel, zinc, and other malleable materials. Non-metallic materials such as plastic can be used for flashing, but many have the disadvantage of not being able to withstand weathering and direct sunlight.

Types of Flashing You Can Install

There are various types of flashing and many of them derive their names from the shape they come in or location of use.

  • Roof Flashing – This is normally used around roof discontinuities or projections. It helps in deflecting water away from the joints or seams and in roof valleys with concentration of water runoff.
  • Roof Penetration Flashing – These are installed to waterproof places where cables, pipes, supports, and other roof protrusions are built.
  • Channel Flashing – This is a U-shaped specialised roof flashing installed to catch water at the points where the roof meets the wall.
  • Valley Flashing – This type of flashing protects the valley at the intersection of two roof planes.
  • Other types of flashing include wall flashing, pipe flashing, step flashing, and counter flashing.

Flashing Design and Installation

As you select flashing material such as bespoke aluminium, you have to bear in mind the points of contact for the flashing because of incidences of chemical reactivity with other materials. Galvanic corrosion has been cited as one of the main causes of premature flashing and roof failure.

Aluminium is largely non-reactive and by far the best material to use in roof flashing. It impressively withstands environmental and physical abuse thus keeping your roof intact and the interiors safe for such a long time.