| Frequently Asked Questions about Coal Tar Built-Up Roofing |
A: Pricing for a complete system, including insulation, can vary a great deal depending upon many different factors. For a typical project that is about 50,000 square feet that includes a layer of Kop-R polyisocyanurate insulation, a fiberboard overlay and a 20 year warranty, expect to pay from $4.50 per square foot to $7.50 per square foot.
Q: What are some of the advantages of coal tar?
A: It's a pretty long list, but a distinctive advantage of this system lies in its water resistant characteristics. Because of its tight molecular structure, coal tar is impervious to standing water. Koppers takes no exception to standing or "ponded" water on its warranties. Most single-ply and asphalt roofing systems will exclude this condition from coverage. In addition, this feature makes our system very price competitive when compared to other systems that require tapered insulation to provide for drainage.
Coal tar roofs are very resistant to corrosive environments (i.e., animal fats, oils, greases, acid rain, alkali, mold, bacteria, etc.). This allows our products to perform in some of the harshest conditions a roof might ever become exposed to.
Compare life cycle costs of roofing systems. In several independent studies, coal tar roofs have the longest average service life, except for metal. So look at a 30 year life cycle. A coal tar roof may require maintenance at the end of 20 years, then go another 10 years. A single-ply roof may last 15 years, then require tear-off and replacement for another 15 years. Based upon this scenario, our system is one of the best values on the market.
Maintainability is a feature of built-up roofing that allows you to prolong the life of your roof. Semi-annual inspections by your Koppers Professional Roofing Contractor or roofing consultant can minimize problems by catching them early. When the time finally comes to replace your BUR, you have an opportunity to work it into your budget.
Q: Are there any health, safety, and environmental issues I should be aware of?
A: Absolutely. Just about every product on the market has some type of impact relative to health, safety, and the environment. For this reason, Koppers has published a booklet called "Guidelines: Health, Safety and Environment for Coal Tar Built-Up Roofing". In this publication we discuss labor and environmental standards, OSHA standards, epidemiology and roofer studies, and more. We also provide guidelines for the use of both asphalts and coal tars in the installation of built-up roofing systems. There are also products on the market designed to significantly reduce smoke and fumes associated with hot applied roofing materials. Contact your Koppers representative for more information.
Q: What is the difference between coal tar and asphalt?
A: They are developed from completely different sources. Asphalt is a product made from crude oil. Coal tar comes from coal, as its name implies. This means that even though these two products look and may even smell similar, they are very different. Asphalt has a higher softening point than coal tar. This characteristic makes it well suited for higher slopes, where it will solidify and should stay in place. Coal tar has a lower softening point, which allows it to actually flow on warm days. Coal tar can actually heal itself of minor cracks and punctures. This cold flow property is also why coal tar cannot be used on slopes above 1/2" for organic felts, and 1/4" for tar coated glass felts.
Q: What are some of the limitations of coal tar BUR's?
A: Slope is the most significant limitation of coal tar roofing systems when compared to asphalt BUR's. When using organic coal tar saturated felts (Tarred Felt), the maximum slope allowed is 1/2" per foot. When using coal tar coated glass felts (Tar Glas), the maximum slope allowed is 1/4" per foot.
Coal tar has a relatively low softening point, so it must always include a gravel surface. Gravel provides many benefits, including protecting the roof from the sun's rays, protection from foot traffic, weight as additional protection for wind uplift, reduced surface temperature, and protection from burning brands. But most importantly, gravel allows us to include an additional minimum average of 70 lb/square of coal tar in the installation of the roof.
Q: Which BUR products are sold through Koppers?
A: Koppers provides a complete line of products relative to the roof membrane. Bitumen, felts, base sheet, flashing, cements, primers, and even aluminum roof coatings can all be delivered to a project on a single flatbed truck. Insulations such as Polyisocyanurate and Perlite come from different plants. They would ship on their own independent trucks.
Q: Does Koppers provide the accessories like walkpads?
A: No, items like walkpads, gravel, fasteners, etc., are not provided by Koppers. We do offer a complete line of metal edge systems called Kop-Klad that include counterflashings, copings, gravel stop/fascia, etc. We also provide heavy duty gravel guards to protect the roof drains from gravel, bitumen, and other debris.
Q: Do you sell direct to roofing contractors?
A: Koppers is a manufacturing concern. In Commercial Roofing, 98% of our sales are to Koppers registered distributors throughout the U.S. The distributors stock our material and provide for timely delivery to your project. Contact your Koppers representative to find a distributor near you.
Q: Must all flashings have both a termination bar and a counterflashing?
A: Yes, we take our warranty obligations very seriously, and our decades of experience shows that the termination bar provides significant holding power to keep the flashing plies from slipping off that vertical surface. One exception is when a wood nailing surface exists behind the top of the flashing. Then the termination bar can be safely replaced with nails 8" o.c. Nails must have minimum 1" diameter cap.
Q: I don't like the smell, is there anything I can do?
A: Yes, there are several after market products out there that are designed to significantly reduce fumes and odors. One is the Reeves Afterburner. It works by burning off the smoke as it passes through a stack on top of the bitumen kettle. Another product cleans the smoke and fumes through a series of filters. Both offer a reasonable improvement in air quality. Cost will vary, ask your Koppers representative for more information.
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