A total roof blowoff is a facility manager’s worst nightmare. Whether the destroyer is a Midwestern tornado or a Gulf Coast hurricane, older, out-of-code facilities will be the first victims. However, as was seen last year in Joplin, Mo., some disasters are equal-opportunity destroyers. Today’s code provides guidance for most wind storm scenarios and leaves it up to designers to determine the life safety role of the structure.
Nevertheless, avoidance of a blow-off is not the equivalent of a trouble-free ride. Direct-impact winds 150 miles an hour or stronger will damage anything short of a FEMA 361/ICC500 storm shelter. Resisting damage from the kinds of severe hail that pelted several Midwestern and Southwestern states during the 2011 spring storm season presents a Herculean challenge for most roofing materials.
In short, even if school officials and architects have done everything right, sometimes everything will go wrong.
Designing protection
Before talking about how to prepare for what can go wrong, one must identify some considerations for roof systems:
When it comes to roofing, thicker and stronger is better, but the details of how water is kept out are critical.
•Metals. Metal roofing assemblies need to be tested to local wind-storm design criteria. This means that tests must be run not only on the panels, but also on the decking or the framing purlins (as called for by the design) to which the metal roof panels are attached. Structural standing-seam metal panels rated for higher wind storm criteria typically are 22 gauge or thicker.
Air and water leakage testing is essential to show that a system is not only strong, but also watertight. At a minimum, standing-seam metal systems should be tested by ASTM E 1646 and ASTM E 1680 to 20 psf of pressure.
•Single plies. A low-slope roof single-ply application must be adhered fully to meet higher wind-storm criteria.
Even a hail-rated single ply is not going to withstand the sharp objects that blow around during a tornado or hurricane as effectively as a metal roof or properly surfaced modified bitumen membrane.
•Modified bitumen. High-tensile and tear-performance membranes provide an additional strength and safety factor when extreme weather strikes.
If gravel is embedded in a flood coat (as acceptable by code), this surfacing can provide superior protection compared with most other roof systems.
The strength of modified bitumen roofs often is dictated by the insulation assembly, so just like metal, the entire mod bit roof assembly must be tested for wind storm resistance.
•All commercial roofs. A properly maintained roof, whose structural integrity is intact when storms hit, is going to outperform a similar roof system that has been neglected.
Factory Mutual Global and Underwriters Laboratories Inc. are two of the most well-known entities that have independently established wind uplift and other performance standards for commercial roofing, upon which most building code requirements are based. However, there are other test standards (TAS, ASTM, AAMA) that exceed building code requirements, which may be specified depending on a school’s safety requirements.
Education institutions should consult with a qualified roofing professional to identify roofing standards and code requirements that apply to their facilities.
Setting Expectations
Prior to storm season, a committed roofing partner can help schools establish a disaster response plan to minimize a storm’s impact in the event of roof damage. Having a plan in place, with contractors ready to respond, is the best way to minimize the impact of storm damage on a facility.
The challenge is securing the services of a dependable contractor after a storm when everyone around also is seeking help for their roofs. Contracting for disaster-response services before you need them is the best way to ensure help will be available when you do.
The process:
•Before signing any contract, schools should perform comprehensive inspections to assess the condition of all roofs; that ensures that they will have reliable information on the existing conditions of their buildings. This is critical to determining which type of services to be contracted, and will help schools make knowledgeable decisions after a storm. It is common to work with a disaster-response provider to perform such comprehensive inspections. Make sure that a company has local representation and its primary business is roofing.
•Based upon inspection results and specific needs, a disaster-response plan should prioritize building areas and separate facilities by importance. At a minimum, this plan should:
-Identify a basic scope of work to be performed when a contract is activated.
-Identify a clear understanding between temporary repair and permanent repair.
-Identify a group of first-responder contractors.
-Identify specific customer contact information for each facility, in addition to security and access requirements for each building.
-Identify the local representative’s contact information for the disaster response service provider. If working on a regional level, make sure all regional managers are listed as well.
A contract for disaster-response services should be signed and renewed every year so that provider performance may be evaluated after each storm season. A contract also should include a specific rate schedule for the agreed-upon scope of repair work. Negotiate this rate schedule ahead of time to protect the school organization from inflated pricing after a storm.
The contract should make available multiple first-responder contractors who are preapproved to work with whatever variety of roofing materials a school may be using. Multiple regional responders, rather than a single local contractor, should be available because local contractors likely will be affected by the same storms.
In addition to the roofing partner having a local representative in place larger companies may be able to provide regional support as well, which can be helpful should local representatives be affected by the storm. Ideally, both the local and regional representatives should be familiar with a school’s roofs and understand its priorities before their assistance is required.
Finally, the roofing partner should be capable of providing a range of roofing-related material solutions, as well as general contracting services, for seamless delivery of whatever combination of materials and services is required.
Although schools should expect to pay for whatever time and materials are required to ensure the long-term preventive maintenance and code compliance of roofs, there should be no fee attached to emergency response services until and unless a schools need them.
When and if disaster response services are required, schools can expect a local representative to prepare an immediate assessment of damages. This assessment will result in a comprehensive scope of work prepared for approval, which should encompass all materials and services required to restore the lasting watertight protection of the roofs.
Although it is impossible to generalize a timeline that is reasonable for all contingencies that may arise, a reasonable turnaround for typical emergency-response services might look something like this:
•If time permits, confer with the disaster response services provider when storm warnings are issued to verify the predetermined disaster-response plan. If any building priorities have changed, be sure to communicate this to the provider.
•If structural damage occurs, verification of building safety by the appropriate code authority must precede any contractor work.
•The first-responder contractor should arrive on site to install temporary waterproofing—if not immediately, then as soon as possible following the storm.
•The local representative should present permanent repair scope of work immediately following assessment of damages.
•Permanent repair work should be completed by a predetermined, mutually agreed upon date.
Minimizing Stress and Delays
Results of studies on the roofing damages during the 2004 and 2005 hurricane seasons show that 95 percent of all roofs designed according to building code received no significant damage. That is an important statistic when looking at loss prevention and maintenance of school facility roofs.
In addition to designing roofs to meet or surpass all building code requirements, the most important prerequisite for expediting emergency services while minimizing stress is to keep roofs performing as specified. That’s why a proactive preventive maintenance program should be part of any emergency response contract.
The critical components to look for when contracting for preventive maintenance:
•Does the contract allow for competitive bidding of labor?
•Will it include a comprehensive analysis of existing roofs to establish a baseline and priorities for remedial work?
•Will the school have online access to all relevant documentation, such as work history, warranties, scopes of work, alternative recommendations and photo documentation before, during and after projects?
•Is the leak-alert notification method redundant and adequate to ensure timely response to genuine emergencies?
•Who will be responsible for coordinating and managing any repairs or reconstruction required?
•On what criteria have the contract’s storm-ready contractors been selected, e.g., are they financially sound and technically competent for the expected range of work required?
Finally, schools should work with an organization well-acquainted with the procedures required by the Federal Emergency Management Agency and the proper filing of insurance claims to expedite any available reimbursements for work performed.
Be prepared
The best way to be prepared for a natural disaster is to have a thorough knowledge of the existing condition of roofs, and a plan for what to do when a storm strikes. Emergency preparedness demands three things:
•Code-compliant design.
•A clearly defined response methodology in advance of any emergency.
•Ongoing maintenance of the building envelope.
Consistent attention to these three issues will minimize disruptions related to all but the most extreme weather conditions.
Pierson, PE, is the engineering services manager for The Garland Company, Inc., a Cleveland-based manufacturer of high-performance roofing materials. He can be reached at [email protected].