What Is Flat Roof Flashing And Why Is It Important?

Flat Roof

What Is Flat Roof Flashing?

A flat roof (low-slope commercial roof) is designed to gently shed water over a shallow angle toward parapet scuppers, gutters, and internal drains. Where different roofing materials meet (as with brick meeting single-ply membrane), gaps between the dissimilar materials are often a challenge. Those gaps are covered by flashing.

Flashing appears in two major types:

  1. A thin, durable but flexible metal that is waterproof and easily formed to fit spaces between materials.
  2. Plastic and rubber flashing, also waterproof and easily shaped, will not break down by touching incompatible surrounding materials

Other, less common materials include the very substances used in single-ply membranes such as TPO or PVC. These materials can be applied separately, in extra layers, around HVAC curbs and other projections. Galvanized steel, copper sheets, and even lead (despite health risks) can all be used effectively as flashing.

Think of any type of flashing as a weatherproof bridge across any potential gaps in your roof.

Where Does Flashing Go?

Flashing serves many functions around a commercial roof:

  • Bargeboard — Flashing along sloped roof edges
  • Cap — Flashing (usually metal) shielding upper edges of the membrane base flashing along the top of a wall or column.
  • Drip Edge — Flashing used on your roof’s perimeter
  • Eaves — This flashing runs along the length of flat edges of a roofing system
  • Saddle — The bridge between incompatible materials
  • Valley — Flashing where two downward slopes of a roof meet
  • Vent — Pipes, roof protrusions, and vents all are wrapped in flashing (and often caulk as well)
  • Wall Abutment — Flashing where roof edges meet walls

Why Is It Important?

Flashing — whether aluminum, plastic, copper, PVC, rubber or even risky lead — is critical to the water-resistance of your commercial roof. Low slopes do not shed water as fast as steep-slope roofs, so the longer water sits, the longer it has to seek weaknesses in your roof.

Water finds a way in if given a chance. Flashing helps prevent roof leaks. Flashing is not caulking, and caulking cannot substitute for the waterproof ability and plasticity of flashing.

Contact us today at Horizon Roofing. We look forward to working with you to help protect your commercial roof with maintenance, inspection, repairs, and reroofing.

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