Building Operating Management

The Advantages of Roof Commissioning





Roofing

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Whether roofing a new structure or reroofing an existing building, facility executives want a roof that performs to their expectations. But how can a facility executive ensure the roof will meet various building code requirements, be built as specified, and meet or exceed the manufacturer’s warranty requirements?

The answer is straightforward. Treat the roof the way many other aspects of the building are treated: Have it commissioned.

Roof commissioning is similar to the commissioning of HVAC and other building systems. Basically, it means handling the roof and envelope with the same attention to detail as facility executives do such internal elements as heating, cooling, air quality and building automation systems.

“Roof commissioning provides a systematic process from pre-design through post-construction to assure the building owner that the roof will perform as expected,” says Thomas Gernetzke of Facility Engineering, Inc., and Region III director of RCI, Inc.

The roof commissioning agent needs to have a well-rounded scope of roofing knowledge. Experience with different systems and roofing types in both new construction and retrofits is essential.

Not everyone feels the new term “roof commissioning agent” is necessary. Patrick Downey of Merik is somewhat skeptical of the new terminology, explaining that traditional roof consulting “does not require rocket scientists, but you do have to execute the basics well.” Downey is immediate past president of RCI, Inc.

Whatever their name, roof commissioning agents and roof consultants give facility executives a third-party perspective. According to Jon-Eric Macias of Construction Moisture Consulting, the underlying concept is to “make sure roofs are designed and built properly so owners receive optimum return on their investment.” Macias is Region II director of RCI, Inc.

And, while the same principles apply to reroofing, Rick Cook of ADC Engineering says he thinks the task is more difficult with an existing building. “More forensic work is involved and the job comes with limitations,” says Cook, secretary/treasurer of RCI, Inc. “Certain conditions may exist and it may not be cost effective to modify them.”

Reviewing Design Drawings

RCI, Inc. experts recommend that facility executives involve roof consultants or commissioning agents from the earliest design stage. “When we review the drawings early on, any changes can be suggested and adjustments made at the most economical time,” says Macias. He also says he believes drawings should be independently reviewed when they are 50 to 60 percent developed and undergo a final check at 95 to 100 percent completion, before the bid documents are published.

The third-party peer review checks for such elements as code compliance and constructability, says Gernetzke. “When a designer is working on the same drawing every day, it’s very easy to get tunnel vision and overlook something,” he says.

Roof and envelope elements that may be pleasing architecturally can cause waterproofing problems. A design review involves looking at such practical elements as constructability and functionality. Downey argues against any roof design that requires interior gutters, for example. Architecturally, the roof and envelope have beautiful lines, “but interior gutters are the most leak-prone design element,” he says.

Where slopes join together, water is likely to concentrate. “All joints are likely to leak,” says Downey. He says he is a proponent of “overengineering the base flashing because it’s most likely to fail.”

Reviewing Shop Drawings

Another key element in roof commissioning is reviewing shop drawings. Though going through shop drawings can be tedious, the leak, premature-failure and wind-uplift devils often lurk there. In fact, Macias says he also looks at the project manual and respective specifications. “They complement each other,” he says.

Cook says he also checks every element related to plans and specifications. “The contractor has to bid what’s in the documents,” he says. “A third-party review assures all the i’s are dotted and the t’s crossed.”

“Shop drawings need to be reviewed to assure there is proper communication between the designer and the contractor,” says John Willers of Rooftop Systems Engineers and president of RCI, Inc. “This is particularly important for tapered insulation layouts.”

Willers says that a problem that can be caught during a shop drawing review is changes in the tapered insulation layout that may not satisfy the design for positive drainage or R-value. A shop drawing review normally would include review of cut sheets for various materials that would be incorporated into the roof system, such as the proper compressive strength for insulation, securing of insulation or membranes particularly at perimeters and corners, proper flashings at curbs and parapets, and sheet metal profiles, Willers says.

Quality Assurance

Making sure the actual roofing installation goes smoothly begins long before the first laborer climbs to work. To ensure it continues going well, it is essential that everyone be on the same page. “Roof consultants often become the owner’s advocate for quality,” says Downey. To value engineer out the expert’s advice can be costly later. “Owners get the lowest level of quality they’ll accept,” Downey says.

“A pre-roofing conference should be held with the foreman in attendance,” says Willers. “Too often a principal of the firm or project manager attends and the foreman does not receive all the proper information. A preconstruction conference will assure that the foreman is aware of such basic items as working hours, noise limitations, protection of air intakes and who to contact in an emergency.”

Downey says that on his jobs, the foreman must be on the job from start through completion, because he feels it’s crucial to deal directly with the leader of the crew. If a foreman has to be changed, Downey says he insists on a second pre-roofing conference.

The importance of the preconstruction meeting cannot be overstressed. “It’s most important that the contractor understands and intends to install the roof as it is specified,” Downey says. “Our specifications may require a higher level of workmanship and may exceed the manufacturer’s requirements.”

At the preconstruction conference, Cook says he makes sure the roofing contractor gets a top 10 list. “Here are the 10 items our inspectors are looking for,” he says. “And those items are different for each job and each system.”

On the first day of construction, the inspector should be on site. “Even with a good set of construction documents, you must have an inspector on the roof to act as a bridge between all the planning and coordination meetings,” says Cook. “The inspector relays that planning information to the workers putting that roof down or that wall assembly in place.”

Construction Phase

Quality assurance is also essential during the actual construction process. With respect to the independent roofing observer, Macias says he believes that more coverage in terms of field monitoring and observation is better than less.

“Materials delivered to the site should be checked to assure that they are correct and that the contractor has properly covered and protected them,” says Willers. Checking materials will ensure that the correct adhesives or fasteners are used, materials are protected from becoming wet, and proper insulation board sizes are used (4-by-4-foot, not 4-by-8-foot, for example).

It’s also advisable to observe the first day of reroofing to confirm that the roofing crew understands the scope of the project.

Macias says that regular inspections during the construction process can catch such items as inadequate fastening or installation of roof insulation. Examples include improper staggering of insulation layers and joints or excessive gaps between insulation boards. Other mistakes an inspector can catch include improper EVT of hot asphalt applications or improper hot air welds of membrane seams.

“The final inspection would primarily address workmanship,” says Willers. “It would also confirm that primary and secondary roof drainage is positive and that all requirements of a project are complete.” Some items to attend to could include installation of ladders, walkways, counterflashings at curbs, proper filling of pitch pans and sloping of the filler, placement of granules (if a modified-bitumen system is used), and any blistering of reflective coatings.

“A final inspection is important to assure the owner that the construction contract has been fulfilled and that the quality of the roof will be such that the service life of the roof will match the design life or warranty duration,” says Willers.

Post-construction Follow Up

Semi-annual inspections after installation also are valuable. These inspections are intended to detect damage from weather or rooftop traffic and clogged drains or unusual membrane weathering so that any problems can be addressed immediately.

“Most roofing problems can be prevented by regular inspections and routine maintenance,” says Gernetzke.

Beyond regular inspections, some owners are opting for continuous roof commissioning, a relatively new concept that provides more in-depth inspection and analyses of roofing performance. “Continuous roof commissioning looks at the roof holistically,” explains Gernetzke. “It involves risk analysis and risk assessment.”

The process also is more thorough and could include infrared thermography, nuclear moisture surveys and even laboratory testing of roofing materials, as well as planned preventive maintenance programs. Though facility executives may have trouble justifying such extensive testing on the average Class A office structure, mission critical facilities often benefit from such attention to fine details.

A simpler and less costly format is roof retrocommissioning, because even well-built and maintained roofs can show clues to potential problems down the road. “It’s standard in our organization to inspect the roof 12 months after installation to tie up loose ends,” says Cook. The retrocommissioning inspection rechecks the roof for concerns, such as ponding or moisture accumulation. The inspection also notes if any flashings have popped loose, thanks to Mother Nature. Cook suggests that retrocommissioning should continue for the life of the facility at the end of every summer and every winter. “Few facility executives do that,” he says.

“Ideally, you want the same person doing these inspections each year, because they become familiar with the roof’s history,” says Downey. Drainage points need to be inspected twice annually, as do the perimeter and each penetration, says Downey. Finally, an overall feel of the roof should be noted.

Any problems should be photographed and located on the building plans, along with a brief description of what was found. After any repairs or preventive maintenance procedures, Downey says he suggests a follow-up inspection to confirm the work was done and done correctly.

“If we do the tried-and-true procedures for construction and for maintenance, the roof and the envelope work,” he says, “we get the longest possible service life out of the building.”

About RCI, Inc.

For the first 23 years of its existence, RCI, Inc. was known as the Roof Consultants Institute. Its members — consultants, architects and engineers — provided facility executives with independent design, planning, inspection and management services for the roof. But as the years went on, RCI members found themselves increasingly called upon to address other concerns with the building exterior. As a result, the organization expanded its mission in 2006 to cover waterproofing and exterior walls and changed its name to RCI, Inc.

RCI, Inc.’s mission is to ensure the credibility of its membership through professional development, ethical behavior and research. RCI, Inc. suggests using an independent roof consultant, sometimes referred to as a roof commissioning agent, to look out for a building’s best interests from the initial conceptual design phase through at least the final inspection.

To ensure that facility executives are dealing with experienced professionals, RCI, Inc. offers three registration programs: Registered Roofing Consultant (RRC), Registered Waterproofing Consultant (RWC) and Registered Roofing Observer (RRO). These credentials demonstrate that the person has passed a rigorous examination process and has verified levels of education and continuing education credits.

Rick Cook of ADC Engineering and secretary/treasurer of RCI, Inc. suggests looking at roofing consultants who can demonstrate their qualifications, which the RCI programs allow. He compares the roofing consultant or roofing commissioning agent with such initials to a certified mechanic. “You want to make sure that the person you hire has the experience and knowledge to make the money you are spending worthwhile,” Cook says.

For more about RCI, visit www.rci-online.org or call 800-828-1902.




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  posted on 9/1/2008   Article Use Policy

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