Roof sampling and testing
Depending on the situation and assembly type, localized water testing can be used. It can be followed by the insertion of probes or roof sampling (cut tests) to confirm the presence of moisture in the assembly. While probes only indicate the presence of moisture within the assembly, roof sampling gives the added advantage of determining what is happening in the components beneath the membrane. For example, are the problems the result of roof failure or due to defects of underlying components?
Cut tests in any assembly should be undertaken by qualified roofing contractors, who can then proceed with the necessary repairs. Many roof membrane manufacturers mandate the use of only trained and approved roofing contractors on their systems. Failure to follow those procedures may result in a violation of warranty requirements.
Limited water testing is another tool to identify the source(s) of water penetration. When undertaking a water test, attention must be paid to minimize damage to the roof assembly or building interior, particularly when working over sensitive areas, such as hospitals (where infection control procedures may have to be considered) or data centers where damage as a result of a water test could have serious financial implications.
In designing roofs, clients often request the inclusion of extended warranties in design documents, as many roofing membrane manufacturers offer 10- to 25-year schemes. Depending on the type, these warranties may cover the membrane only or the entire roofing system.
Although these warranties are included in the price of the roof, they are not free; the owner is paying for them. The cost of extended warranties can vary from a few hundred dollars to thousands, and will depend on a variety of factors including the duration of the extended warranty, roof size, and if the client wishes to purchase wind riders.
These warranties are not a blank cheque for a new roof, as they come with specific clauses that have to be accepted by the owner before they become binding. One of these clauses includes the statement the owner will have to maintain the roof and provide proof of maintenance. Failure to do so may result in the nullification of the manufacturer’s warranty.
Frequency and costs
The frequency of undertaking preventative roof reviews depends on the location of the building and the facility’s ‘importance.’ As a minimum, the National Roofing Contractors Association (NRCA) recommends preventative roof maintenance at least twice a year (fall and spring). Roof membrane manufacturers may have more stringent requirements with respect to the frequency of inspections.
The author advises it is best to conduct additional reviews following significant environmental events, such as flash downpours, extreme wind (including micro-bursts), hail, snow, etc.
While two visual reviews per year are enough for a typical building, the frequency may be increased based on the sensitivity of building use and components within the facility. For example, a water leak in a transformer station may shorten out electrical switching gear, and hospitals may have to take out rooms, as water damage my trigger infection control protocols, while a leak into a data center may damage servers.
Although there is no standard (with respect to frequency), the author recommends a thermographic roof scan at least once every five years, as it may indicate a problem beneath the membrane that may not be visible during a visual review.
Who can undertake a review?
Walking on a roof can be hazardous, and therefore, property managers/facility operators are discouraged from undertaking roof inspections. The author recommends retaining qualified roofing consultants to undertake these reviews as they are properly trained and knowledgeable about the nuances and typical failure modes of the roofing system(s) in question. Alternatively, owners may also seek guidance from the membrane manufacturer if the roof is under an extended warranty.
Roofs are subject to extreme physical and environmental conditions. They are, for the most part, the first line of defense against exterior elements, and, in many instances, the most neglected building element. Roof maintenance does not have to be a very complicated and time-consuming endeavor. With qualified people, it can be cost-effective and go a long way toward extending the life of a roof, as problems can be caught early and properly addressed. However, failure to conduct proper maintenance will have a significant financial impact should an unscheduled roof replacement be required. So, do we keep ignoring the car’s engine oil light?
Ted Katsoris is a practice lead in the Building Science Group of Building Specialty Services at Morrison Hershfield’s Markham, Ontario, Canada, office. He has extensive experience in the fields of building science and building envelope repair/rehabilitation, as well as contract administration. Since joining Morrison Hershfield in 2004, Katsoris has overseen more than 800 projects. He brings more than 30 years of combined contracting and consulting experience to any project he undertakes. He can be reached at firstname.lastname@example.org.