Roofing: Asking the Right Questions

July 05, 2018Roofing

When it comes to determining whether to repair, replace, or restore a low-slope roof *, there are a few necessary factors that must be taken into consideration at the outset of this process. Consulting with a professional, qualified roofing contractor can help you make the proper assessment but knowing the right questions to ask is a critical first step. Below is the second article in our four-part roofing series:

Q. Has the slope in the existing roof system been properly identified?

This is a more complex question than it seems.

The slope — also referred to as pitch — on a low-slope roof is what causes water from rain, snow, ice, or even rooftop air conditioning systems, to drain off of the roof and preferably within 48 hours. Even though some manufacturers of roof systems will warrant their products to perform with standing/ponding water, it is best to have all water removed from the roof as quickly as possible. Some membrane roofs, such as PVC, are known to loose plasticizers more quickly when allowed to remain submerged under water for indefinite periods of time resulting in a far more brittle membrane which is much more susceptible to damage from hailstone impacts.

To create slope, which is usually required by building codes to provide positive drainage, in a roof system, it is typically either in the design of the structure and completed during the initial construction process or it can be achieved via a tapered insulation system. However, once the roof system has been installed, it may be difficult to determine from the rooftop whether the slope is due to either of these methods unless core samples are taken.

Coring** a roof is a relatively simple process using a roof coring tool. This tool consists of a two-inch pipe with large serrated teeth on the bottom and has small T-shaped handles that attach to the top and is inserted through the roof system with a firm downward, twisting motion until the roof deck is reached. Once the coring tool is removed from the roof system and the core removed from within the coring tool, all components of the roof system will be exposed. Taking cores in multiple locations will verify the thickness of any and all insulation/substrates, the existence of prior roof systems that have not been removed, the thickness of the top surfacing membrane as well as the number of plies in a built up roof (BUR). Measuring the thickness of the insulation from multiple locations will greatly assist in determining whether or not there is slope in the building structure or if a tapered system is in place.

Another benefit of coring the roof is that it can also verify whether or not the roof system has been wetted by moisture intrusion. Roof components such as wood fiber insulation, gypsum, and others can and will deteriorate due to exposure to moisture and especially long-term exposure. If there is moisture, the next question is:

Q.Is the moisture isolated to areas small enough that they can be removed and replaced economically as part of a roof repair or is the moisture so widespread that complete removal and replacement of the roof system is required?

Roofing manufacturers will not offer warranties and will void existing warranties on roof systems installed over wet substrates.

While this may seem like a lot of information to digest, this is only a very high level view of this topic. If you would like more information, please feel free to submit your questions to Billy Owens, VP of Roofing:

By obtaining a complete answer to the initial question of whether or not the “existing roof system has been properly identified?” you will be one step closer to an accurate and comprehensive cost estimate based on an apples-to-apples comparison which is the best and right solution for you and your client.

Be sure to join us for Part Three of this series when we address “When to repair a low-slope roof system versus complete replacement?”


*Low-slope Roof: a roof in which the uppermost part is installed at a slope of 2/12 or less. (ASTM standard E1918-87)

**Roof Coring: this should only be done with approval of the building owner and by a qualified roof technician. If the existing roof is covered by a warranty, only a certified roof applicator/installer of the existing roof system should perform the coring as well as the repair of the roof after the coring is complete to prevent any possible voidance of the roof system by the roofing manufacturer. Roof cores can be completed in a number of other ways and of far larger sizes than the coring tool. Typically, larger cores are taken when there are questions as to whether or not hailstones have fractured either the top surfacing layer or subsequent layers such as in a BUR system.