Transitional Detailing

Transitional detailing encompasses the design and execution of a detail that bridges both the waterproof and water shedding requirements at points on a buildings envelope where horizontal and vertical planes intersect.

Some examples of transitional details are:

  • parapet walls and railings surrounding decks and roofs
  • windows, skylights, and chimneys
  • exterior doors that open onto decks and roofs
  • drainpipes that go through walls
  • junctions between sloped and flat roof sections
  • valley transitions adjoining two different sloped roof pitches
  • protrusions (skylights, chimneys, vents, stacks, ect.) installed with 12”’s of a valley on a sloped roof

Attention to these details is critical to ensure the interior of the building is protected from wind, snow, ice and rain. Poor attention to transitional details cost building owners tens of thousands of dollars in preventable costs related to water damage.

Waterproof detailing vs. Water shedding detailing

In order to design a functional transitional detail one must have a clear understanding of how waterproof detailing works in relation to water shedding detailing.

Waterproof details keep water out when water moves in all directions like on a flat roof or horizontal plain.

Water shedding details keep water out only if the water moves in one direction like on a sloped roof or vertical plain.

The level of complexity associated with transitional details can be overcome with experience, attention to detail, skilled workers and proper supervision. Unfortunately, poor transitional detailing design and execution and a lack of supervision are still ongoing problems in our industry, particularly in the residential sector.

At Westcoast Roofing Systems we have the knowledge to design and the skill set to install and provide a high level of supervision.

Damage to buildings caused by leaking transitional details is often significant and costly. Spending more money to get the job done right can save you tens of thousands of dollars down the road. Transitional details are not the place to save money and could explain the cost differences between various estimates that appear to be for the “same work”.

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