Letters

Questions about the solar bar

In the June issue of Professional Roofing, Ashley St. John, Professional Roofing's associate editor, wrote "The world's first solar bar," page 46.

The story is interesting, but two important things, in my opinion, were omitted. There is no mention of getting a permit or whether plans and specifications by a state-approved architect or engineer were required.

Requirements vary from state to state, but the issues are important in every state and are important information for inclusion in any article concerning reroofing.

Carl Hudson
VCE Inc.
Nashville, Tenn.

Robert Molnar, estimator and project manager for Wm. Molnar Roofing Inc., Riverview, Mich., responds: Plans and specifications were required, which were provided by the architectural and structural engineer at Kulick Enterprises Inc., Wyandotte, Mich. The city of Southgate, Mich., required a roofing permit, which was obtained. Southgate was gracious enough to waive the mechanical permit.

I just read your article about the first solar bar. I cannot believe a 6-kilowatt system can save $10,000 per year. You would have to pay $1 per kilowatt-hour (kwh) for that to happen. A pretty standard electricity rate is about 15 cents per kwh, and if that is the power cost, the roof system would take about 30 years to pay back. The total cost after rebates for that system is about $55,000, which is $9 per watt, which is not a good deal.

John Hubiak
Hubiak Construction
Sonoma County, Calif.

Molnar responds: I am not aware of the cost-saving details, but I know they most likely are a combination of federal tax incentives, power savings (via the electrical system), and roof insulation and solar reflectivity not to mention the amount of revenue the project has attracted to the bar. The state of Michigan does not offer tax incentives as do California, Illinois, New Jersey and many others. It operates on a grant system that would probably be tough to get into unless you are pretty sophisticated.

Roof systems fail FM 1-52

I enjoyed Mark S. Graham's, NRCA's associate executive director of technical services, column "Concerns with FM 1-52 testing," June issue, page 26.

As a certified testing company, we are contracted primarily by property managers, consultants and contractors to conduct membrane uplift testing of new and existing roof systems for wind resistance.

The FM Global membrane uplift test is extremely difficult to pass. For example, take a roof system that was installed before 2006. Such roof systems were not, to my knowledge, designed to meet FM Global wind-design requirements and are sure to fail at some point per the required FM 1-52 wind-design pressures. Failure of existing roof systems is anticipated and expected. It is always interesting to see just how much negative pressure an existing roof system can withstand and where the point of failure occurs.

On the other hand, in the Miami-Dade area, for a new roof system, a contractor would have to get a product approval per the Florida Building Code and provide enhanced fastening for perimeters and corners (if the system is mechanically attached) to meet enhanced pressure zones. Once that is completed, if the roof system is insured by FM Global, it would have to meet FM 1-52 requirements. That same roof system then would be re-engineered to higher design pressures and for enhanced pressure zones, taking into account a safety factor. Then, whichever of the two systems is more stringent would be installed.

Upon roof system completion, FM Global requires field testing to confirm a roof system meets all wind-load requirements.

We have tested several existing and newly installed roof systems in recent months according to FM 1-52. Not one has passed.

Let's face it: All engineering is done with good intentions but is in theory only. Field testing before full-scale roofing operations is called in situ testing and is part of the Florida Building Code. Test your darn roof systems before full-scale roofing operations! If a roof system fails, its components can be changed or fastening patterns can be corrected.

I have been telling contractors to test engineering in the field for quite some time. They are primarily concerned with the associated costs. Where will contractors get the money? I don't know. What I do know is that I have seen newly installed roof systems with additional fasteners installed and stripped in throughout a roof system in an attempt to meet uplift requirements.

Anthony Tomassi
Received via e-mail

Graham responds: Thank you for your comments and sharing your experiences in dealing with FM Global guidelines.

You raise a good point—one I have addressed in another article. Roofing professionals should understand compliance with FM Global guidelines, in itself, does not necessarily provide for compliance with the minimum requirements of building codes. (For additional information, see "Understanding wind-resistant design," March 2007 issue, page 43.)

NRCA recommends designers design roof systems that comply with the requirements of the building code that is applicable for the specific location of the building being designed. Furthermore, if a building is FM Global-insured or compliance with FM Global guidelines is being considered as a design requirement, this will entail an additional step in the design process separate from providing for building code compliance.

Also, it is important readers understand compliance with a building code's minimal requirements is a legal requirement enacted by a local ordinance. FM Global guidelines are intended as recommendations by FM Global to its insureds.