www.mrca.org  —  Midwest Roofer
20
TECHNICAL & RESEARCH
designed and installed roof system deserves warranties 
issued by the contractor and membrane manufacturer 
as a gesture of quality, not as a guarantee that the 
roof system is a suitable solution for waterproofing and 
energy management, or that it meets building codes.
Modern designs account for the difficulty of installing 
roofs (the art) to meet raised expectations of building 
performance (the science) and, of course, all within 
governing building code requirements. The practicality 
of installing membrane and insulation continuity can 
sometimes resemble a game of “Twister” that requires 
coordination between the roofing contractor and 
representatives of other trades, including mechanical, 
electrical, plumbing, fenestration, cladding, and 
insulation contractors, during new build construction 
projects. In a roof replacement project, roofing 
contractors are often hired as general contractors, 
subcontracting other trades, as the only way to 
complete a roof replacement without risking water 
infiltration.
Before designing a roof replacement, it is essential 
to understand the existing building’s construction, 
including the type of structure and roof deck, existing 
mechanical and plumbing systems, parapet and 
adjacent wall construction, rooftop equipment, and 
penetrations. It is counterproductive to design a 
roof incompatible with existing materials or building 
detailing, as the connections could fail, allowing for air 
and moisture infiltration (resulting in energy loss and 
leaks). Removing wall parapet claddings to ensure 
continuous barrier membrane and insulation transitions, 
lifting mechanical units to complete curb detailing, and 
ensuring sufficient drainage capacity and strategy are 
all steps that must be intentionally and carefully detailed 
and performed to ensure a successful roof replacement.
Relying on the roofing contractor’s technician to design 
the transition between adjacent wall and parapet 
detailing, building materials, and roof accessories 
without professional direction creates the possibility 
that the installation may not meet building codes 
and building science best practices. This is not a 
slight towards a roofing technician’s ability but is an 
acknowledgement of the cooperative approach between 
the roofing contractor and design professional that roof 
replacement work should follow. In turn, the designer 
must be mindful of the difficulties, limitations, and 
obstacles associated with roof construction, as well as 
the notion that what may look good on paper may not 
be possible or practical to install. Weather conditions, 
safety, accessibility, and material limitations could all 
transform what initially appeared to be a good design 
idea into an impossible or costly endeavor.
Modern roofing practices and responsibilities
Today’s roofing contractors have, for the most part, 
adapted to the modern ways of roofing. They send their 
crews to project sites with material safety data sheets, 
life safety and rescue equipment, and plans, engineered 
shop drawings for scaffolding and fencing, building and 
road closure permits, and tapered insulation drawings. 
Today’s roofing technicians are trained to install multiple 
types of roof membranes and incorporate them with 
insulation in various configurations of roof systems. 
How they incorporate their ability to work with roofing 
materials into the entire building envelope is where 
accurate contract documentation and site review of work 
in progress by a design professional lead to successful 
roof installations.
With the trend toward municipalities and jurisdictions 
requiring building permits for roof replacement work, 
designers are reminded of their obligation to incorporate 
current building codes and municipal requirements into 
Continued from page 19
Completed modified bitumen membrane built-up at a 
municipal fire hall.

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