Documenting Roof History

Aug. 4, 2006

In the July 2006 issue of Roofing News (Issue 52), I provided drafts of inspection forms that would be useful when conducting semi-annual roof inspections. The forms were divided into eight sections, with the first section being a brief identification of the roof. The forms then suggested walking the exterior of the building (Section 2). Section 3 included an interior walk-around, as well as an interview with building occupants to determine if and when the roof leaked. Only in Section 4 did the forms direct you to the roof, with a general impression and opportunity to photograph items of interest.

The following sections started with a perimeter walk-around, then a detailed look at flashings and penetrations. The membrane section was more detailed, with differing forms being developed for each generic roof type, including bituminous built-up roofing (BUR), modified-bituminous roofing (MB), weldable thermoplastics (also known as TPO single-ply roofing), non-weldable elastomerics (also known as EPDM single-ply roofing), and, finally, spray polyurethane foam. This section noted problems that might be unique to those particular systems. The final part of the inspection form provided space for notes that the inspector might add to the survey.

Philosopher and poet George Santayana once said, “Those who cannot learn from history are doomed to repeat it.” Santayana’s history quotation is applicable to roofing maintenance. It’s necessary to not only develop a comprehensive roof history, but to learn from the history what is working and what is not. Since desired roof life is 20-plus years, roof surveys can profitably be computerized and roofs rated by performance.

Rather than guessing whether warranties are worth the money, an analysis can answer this question once and for all. In addition, once a comprehensive inspection and maintenance program is under way, it will be possible to prove what a good investment a maintained roof is.

To download the attachment to this column, click here. You will note that Section 1 provides contact information for all of the parties that were part of the initial design and construction. When using a roofing contractor for repairs, if possible, use the same contractor as in the original installation. This contractor is approved to do warranty repairs and should be familiar with access and other special needs of the roof.

If a roofing consultant or testing laboratory was used, copies of their reports should be part of the file. This history may help you understand problems that are attributable to its construction, the weather, material availability, or work completed by other trades on the roof.

Section 2 is a detailed section of everything from the deck up. Include data such as whether the steel deck is typical 33 ksi steel or special 80 ksi steel (required for certain wind-resistant single-ply systems). The drainage section should provide information on what the intended drainage was, and documented calculations of drain capacity.

If vapor retarders were specified or used, the materials used should be itemized. However, since air leakage is generally more serious that permeability through the retarder, details should be provided on how roof perimeters and roof penetrations were made airtight. If the roof has had new equipment added over the years, the retarder is often not sealed to insure air tightness (this may result in condensation problems).

Details in the thermal insulation section should include calculations of U-factor, or at least the thickness and type of each insulation used in the system. With the energy crisis, many older buildings are under-insulated; this may justify reroofing (vs. repair) if the owner takes a long-term view of energy costs.

The membrane section should be customized for the different generic roof types. The age of the original membrane is very important, as many of these systems have morphed over the years with improved sealants, flashing materials, edge restraint details, and more. In many cases, the existing membrane can be upgraded to perform for many additional years if you can identify the weak links and fix them. Attachment methods for the membrane and insulation may also have changed over the years to meet more stringent building code requirements, especially in high wind areas.

Flashings are, in general, where most roof problems start. The roof file should have as-built drawings of what was installed at a reasonable scale (at least 1/4 inch to 1 foot). Manufacturers’ recommendations may have evolved, so you need to be able to compare what you have to what is now recommended.

Sheet metal gets its own section in the history file, especially for field fabricated details. References to the SMACNA manual, as well as the NRCA and manufacturer details are useful, but these are 'guide-details' and may not be exactly what you have in place. Fastener back-out and metal fatigue are two items that need to be addressed here, as well as corners, terminations, and crossovers.

Section 3 provides warranty information. Most manufacturers provide the building owner with a recommended list of maintenance items that are not covered under the warranty, including debris control, punctures, and anything other than leakage. A copy of the actual warranty should be in this file, as well as current information on how to report a leak.

Section 4 is for a broad generalization on how the building is to be used. High-humidity interiors, cooler and freezer buildings, and roofs that are exposed to corrosives, fats, oils, and solvents all require special design. When building usage changes, the need for ventilation or vapor control may change as well.

Section 5 on previous maintenance and repair should be supplemented by written documentation of what took place and why. Photographs of problems, their location, and subsequent repairs should also be part of the roof file and reviewed by the roof inspector when preparing to conduct a new roof survey.

Asphalt Roofing Manufacturers Association
Roof Coatings Manufacturers Association
Roof Consultants Institute
National Roofing Contractors Association
Spray Polyurethane Foam Alliance
Sheet Metal and Air Conditioning Contractors’ National Association

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