Architects and Roof System Designers: Your Details and Drawings Are Seriously Lacking Design Intent

Dear Mr. and Ms. Architect and Roof System Designer:
The following are comments I hear over and over:

  • “Seventy-five percent of the time I cannot determine what roof assembly an architect wants from a spec.”
  • “One always feels they have to play private detective and try to figure out what [a roof system designer] actually wants.”

As an architect and registered roof consultant, I take great pride in my roof system designs and detailing, which are project specific, at minimum meet the code, and more often than not exceed code with all conditions and building components that impinge on the roof detailed for the specific project. In listening to construction managers, general contractors, roofing contractors and suppliers talk, you would think that architects barely know that the roof is on top of the building! It seems most do not even have basic knowledge and certainly don’t know when water may flow uphill. This is embarrassing to hear! It starts in the university with the curriculum placing all emphasis on building design and not how to actually construct a building. In many ways, this is good for my firm as we are busy fixing what should never have required fixing.

Peer review of several projects designed by very large (and what you would assume to be very sophisticated firms) and even small boutique firms reveals the following:

A. The roof system design is not code compliant in regard to tapered insulation.

B. The roof system itself is not code compliant, but contract documents require “contractor to verify or be responsible for code compliance”. This begs the question: Who is being paid to design? Is it the architect or the contractor?

C. Structural and, especially, structural lightweight concrete pose significant roofing challenges and architects have no clue about that, resulting in roof systems in danger of imminent failure.

D. The accuracy of construction documents in general is very, very low. Even I cannot often determine what roof assembly an architect wants from a specification.

  • 1. For example, architects do not list products in the specs that will be used in the assembly.
  • 2. Substrate boards, cover boards and vapor barriers are frequently listed in the specs but never shown on the plan.

E. The detailing of wall air barriers to roof vapor or air barriers is not shown and certainly no definition of responsibility prescribed as to who is to tie these materials together.

F. Understanding of material limitations is non-existent.

  • 1. Weather, wind, cold, snow, humidity and temperature affect the installation of roof system components. I especially get a kick out of seeing water-based adhesives being specified for construction taking place in winter; this means future work for my firm.

G. Roof edges and how they terminate at high walls is never detailed.

H. Roof drains and curbs are improperly or not detailed.

I. Specifications are inadequate—often boilerplate generic—and do not match the drawings. I’ve also seen non-specific details that are not to scale or do not reflect actual conditions.

  • 1. Design wind speed is not given when appropriate.
  • 2. Warranty requirements are in- correct, not thought-out or not specified at all.

J. Architects or consultants sometimes have multiple designs listed in the specification, leaving it to the con- tractor to issue RFIs that, more often than not, are not answered.

  • 1. These inconsistencies lead to frustration and, in many cases, the contractors just decide it is not worth the time or effort to even bid the project or add a good deal of money to cover undefined items.

K. I’ve witnessed owners who have hired professionals to design build- ings costing hundreds of millions of dollars, and yet these “professionals” often do not exhibit the standard of care expected.

  • 1. Poor designs compound when met with an irresponsible contractor who will not do his or her due diligence and investigate what is needed to install a quality system.

Illustrations: courtesy of Hutchinson Design Group Ltd.

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