In the not-so-distant past, as a roofing system approached the end of its warranty period or began to show significant signs of advancing age, it was time to talk about installing a new roof. Not so anymore.
Building owners are increasingly looking to roof restorations to extend the lives of their existing roofs. It is an investment that can deliver big returns. The roof can be returned to near-new condition: watertight and able to withstand whatever Mother Nature dishes out.
There are a few other benefits. The cost can be dramatically lower than replacement. The building’s energy efficiency can be significantly enhanced. There is far less disruption to normal building activities. The roof will be backed by a fresh warranty. And it is a much more sustainable choice.
But not every roof is a good candidate for a restoration. A variety of factors must be weighed in selecting the best way to restore a given roof. Every job must begin with the contractor asking two important questions:
- Should the roof be restored?
- If so, how?
Restoration or Replacement — There Is a Difference
Roofs can be restored in two ways. The roof can be coated with one of a variety of fluid-applied systems, including silicone, acrylic, and styrene-ethylene-butylene-styrene (SEBS) thermoplastic elastomer. Or the existing roof can be recovered with new thermoplastic polyolefin (TPO), ethylene propylene diene monomer (EPDM), polyvinyl chloride (PVC), or modified bitumen.
In either case, a restored roof is not the same as a brand-new roof, and it should not be presented to owners as such. It is imperative that contractors understand what roof restoration can — and cannot — accomplish and the different mindsets required when approaching restoration and replacement projects. Then they can communicate that to the owners.
Too often, restoration is thought of as a miracle that will fix any problem on any roof. Be warned: It is not. Restoration will extend the life of a roof that is in good repair, delaying for years — even decades — the day when a new roof is needed. However, it will not make an unsound roof sound again; in these cases, replacement is in order. It also will not magically resolve pervasive leaks, ponding water, and other performance issues. The appropriate repairs must be made before the roof is restored or the problems will only get worse.
Contractors also must view replacement and restoration projects through different lenses. On a tear-off project, the existing roof’s type, material manufacturers, and installation methods are irrelevant. When restoring a roof, though, those things are highly relevant. Compatibility with the existing roof is a vital consideration when choosing the coating system to be used or the adhesive that will be used to attach a new membrane.
Assessing the Existing Roof
Stories of roof restoration “failures” have circulated through the roofing industry for years. These tales have given restoration a bit of a black eye — one that is undeserved. When restorations fail, the cause is virtually never the products used but rather because the roof should not have been restored in the first place. The products were used in an environment they were not meant for.
It is essential, therefore, to complete a thorough assessment of the existing roofing system — from the top layer to the roof deck. This deep dive will provide such details as the roof ’s age; the components used initially and added since, including their types, manufacturers, quality, and typical lifespans; the installation methods used; the quality of the installation; and the roof’s current condition.
The contractor should start by completing a thorough visual inspection of the roof. Trash and debris should be removed to provide a clear view of the underlying and existing roof substrate. Among the things that should be looked for are:
• Ponding water or decking that is rusted, rotted, or cracked. These may indicate that the roof deck has reached the end of its service life and the roof must be replaced.
• Spots that feel soft when walked upon. These are signs of saturated insulation. Further investigation should be done to determine whether the leak is small and can be repaired or whether the problem is more pervasive.
• Splits in the membrane. Those may be signs of unanchored insulation or damage caused by hail or temperature swings. The reason must be determined so that the appropriate action can be taken.
The assessment should also include core cuts and a moisture survey.
Similar to soil samples, core cuts show all layers of a roof, revealing its history and condition. Cylindrical cuts, approximately 1.5–2 inches by 1 foot (3.8 cm by 30.5 cm), are made to remove samples of all roof layers down to the deck. One sample per 40 to 50 squares (approximately 371.6–464.5 m2) should be taken (and more samples taken if the roof appears to be in poor condition).
A moisture survey is essential to ensure that the underlying substrate is dry. Several options are available:
• Infrared Moisture Scan: A handheld or drone-mounted infrared camera is used to scan the roof for moisture. Wet areas will glow “hotter” because the moisture will retain heat longer. The roof should be scanned at dusk when the distinction between “hot” and “cool” areas will be greatest.
• Electronic Leak Detection (ELD): These tests require that a conductive material, such as Detec TruGround Conductive Primer, has been applied to the substrate directly below the membrane. Water is applied to the roof surface, which is then scanned using a high-voltage or low-voltage ELD device. If leaks are present, the water will create electrical connections to the grounded roof deck, enabling the device to pinpoint their locations.
• Nuclear Resonance Imaging: This is an alternative to ELD when a conductive material is not present. A robot sends radio impulses into the roof to detect water. The impulses can penetrate up to 2.5 inches (6.4 cm) and are effective in assessing one layer of roofing.
Weigh the Options
Using the data gathered, contractors should consider a variety of factors to determine whether the roof can be restored. If the roof is found to be unsound for any reason, it must be replaced.
If pervasive leaks are discovered, it is safe to assume that the roof has leaked for quite some time and the insulation and roof deck throughout are compromised. The roof should be replaced.
But if leaks are small and their locations are known, they can be repaired and the roof restored.
The building owner’s insurance company often makes the final decision on repairs. From the insurer’s perspective, replacing the roof removes subjectivity; they know that the new roof will be up to code and covered under warranty. But if the restoration will come with a satisfactory warranty and the work can be completed at a fraction of the cost of replacing the roof, insurers will approve a restoration.
The good news is that today’s more robust coatings and single-ply membranes are backed by strong warranties. No Dollar Limit (NDL) system warranties of up to 20 years are available when coating commercial buildings. When recovering a roof on a commercial building, NDLs of up to 30 years are available with TPO and EPDM and up to 20 years with PVC and modified bitumen.
Finally, contractors should not “force” a roof restoration when replacement is truly required. If immediate action is needed to protect the building and its contents but there will be a significant delay in replacing the roof, contractors should employ temporary solutions that will buy the needed time. Temporary options include heat-shrink systems and traditional tarps and sandbags.
Choosing the Right Restoration Technique
Once the decision to restore has been made, contractors should consider the following in determining whether coating or recovering is the best option:
• Does the entire roof need to be restored? If only a portion of the roof is problematic, installing new singleply membrane on that area while leaving the rest of the roof as-is may solve the issue at a lower cost.
•If the roof is coated, how close to “near-new” will it be? If the existing membrane has deteriorated to the point that coating it will not breathe substantial new life into it, recovering may be a better choice.
A fluid-applied roofing system is considered a maintenance system rather than a new membrane or new roof. Thus, the quality, durability, and performance of the underlying and existing roofing system must be of a quality and performance that can be maintained and extended, rather than needing to be replaced or repaired.
• What do local building codes say? In some hurricane-prone areas, building codes allow roofs to be coated but not recovered. Some communities prohibit a roof from being recovered a second time due to the additional weight the new membrane would add. Coatings are usually permitted, however, as they are approximately 1/10th the weight of a new membrane.
Whichever restoration option is chosen, contractors should consult the coating or membrane manufacturer for guidance in selecting the right products for the job. Factors to consider include the existing roofing system type, building type, local climate conditions, local building codes, budget, and desired warranty. Contractors should then carefully follow the manufacturer’s application or installation instructions to ensure a quality project. Manufacturers stand ready to provide support and training, as needed.
Building owners are increasingly recognizing the benefits of restoring their existing roofs and delaying the cost, hassle, and environmental impact of replacing them. A contractor’s first step in helping their clients reap those rewards is a bit of investigative work to confirm that the roof is a good candidate for restoration and, if so, whether coating or recovering is the appropriate choice.
The information contained in this article is for general educational information only. This information does not constitute legal advice, is not intended to constitute legal advice, nor should it be relied upon as legal advice for your specific factual pattern or situation.
This article was originally published in the January 2023 issue of CoatingsPro. Republished with permission.
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