Hail resistance
In areas prone to hail, it is important to select a commercial roof material that can survive its impact. TPO has been studied extensively and offers good puncture resistance. Fully adhered TPO is a good option to protect against punctures. A fleece-back TPO—adhered in conjunction with a high-density polyisocyanurate (polyiso) cover board—provides enhanced resistance from punctures in areas prone to hail and has advanced protection against heat aging and UV weathering.
Coatings have also been shown to help protect a metal roof from damaging hail. This is due to its elastomeric properties, which protect the roof from the dings and dents hail can cause.
Speed
If the timeline is tight, TPO can be particularly versatile as it can be installed quickly by rolling out a 3-m (10-ft) wide sheet and welding all the seams. TPO also has many prefabricated accessories available to reduce the time spent field-fabricating details. However, if many penetrations are on a commercial roof, welding still needs to be done.
Coatings are self-terminating and have no seams. Therefore, if a roof has more penetrations, a coating can be put down quickly and be easier to install.
Investment/equipment
To install TPO on a commercial roof, a heat welder is necessary. This is a $10,000 to $15,000 investment. For small coating jobs, a roller will work, but a serious coatings contractor may want to invest in a sprayer, which typically costs $8000 to $12,000. One should account for expensive installation equipment or extra time when special equipment is not used. Each can increase the overall cost of the job.
Reflectance
Reflective roofs can help save energy costs by reducing the transfer of heat going into a building. It can also improve aesthetics and extend the life of the roof. Both TPO and coatings are similar in their reflective values, as they become a layer of UV and waterproofing on the roof. The difference is apparent when the roof needs insulation. If it does, it is best to put TPO over the insulation. For a solar installation, TPO is more advantageous, as it has a longer guarantee. One can get the most life out of both the roof and solar system in this case. Using a coating with a solar installation is possible if the system is mounted—allowing the roof to be recoated at any time.
Aesthetics
On a visible roof requiring some aesthetic work, an easy solution is using a cover board, TPO, and installing polypropylene honeycomb core sheets over it. If it is visible and aesthetics are a priority, coatings are a good option. If the roof has an existing coating and is visible, it should be recoated.
Fundamentally, more new roofs are going to be TPO—which is the better solution for longer-term warranty. A 35-year warranty can be reached with thermoplastic polyolefin, while coatings typically qualify for a 10- to 20-year warranty.
Lee Martucci is a senior product manager responsible for coatings and asphaltic products for GAF in Parsippany, NJ. He has more than 25 years of experience in marketing and product management where he has been focused on the development, launch, and management of building material products for both the business-to-business and business-to-consumer markets. Martucci holds a bachelor of science in business and economics from Lehigh University and earned the New Product Development Professional (NPDP) certification from the Product Development and Management Association (PDMA).
