SO MANY CHOICES
- By Thomas Dolan
- August 1st, 2005
In the good old days, roughly 50 years ago, there were basically two types of built-up roof (BUR) — asphalt or coal-tar-pitched base, with three to four-ply applications. If you used tar, you had a gravel surface that acted both as a stabilizer and solar shield. The asphalt choice came with either a smooth or gravel option. These roofs were built to last the lifetime of the building. The question is, if the old-fashion BUR didn't break, why fix it? The answer is technology.
Many manufacturers felt they could build a better rooftop, and in many ways, they have. But this, in turn, has created problems that didn't exist before. It's a bit like if you have one good watch you know the time. If you have nine or 10, you're not too sure.
Suppose you have a roofing problem, and the contractor tells you your entire roofing system is so old and decayed that your best bet is to tear it out and put in a new one. How are you to know, unless you majored in read'n, write'n and roof-metic, if he's looking to enhance his bottom line or to save you money? "We are finding that in a lot of situations, schools are re-placing roofs that don't need to be replaced," says Chris Salazar, vice president, Sales/Marketing, Karnak Corporation, Clark, N.J., a coating manufacturer. Just as technology has increased the number of different types of roofs available, it has also increased the number of coatings. Salazar's point is that it's much cheaper to repair an existing roof with an appropriate coating than to put in a brand new roofing system -except, of course, in those situations in which the roof is so decrepit the only thing to do is gut it and start over.
Here are some steps Salazar suggests you can go through to determine if your roof needs to be torn out or if it can be repaired. First, he suggests doing a roof evaluation by walking over it and checking for any soft or soggy parts. This can be supple-mented with an infrared scan to spot wet insulation. If the soft roof and/or wet insulation is found and it is limited in scope, repair only that area. "Make sure to remove all moisture traps, for moisture keeps the roof from performing well and is the cause of mold," Salazar warns.
The next step, Salazar continues, is to check the surface for cracks. There may be crevices that are "alligatored," or resemble the skin of that creature. These surfaces may or may not indicate a cracked roof. If the roof is cracked, this necessitates a major repair. But these formations just might be in the surface. In this case, Salazar says, "apply a fiber asphalt emulsion — basically a film of asphalt which helps smooth out the surface. If the alligatoring is very pronounced, then apply two layers of asphalt emulsion with a polyester matt embedded between the two. This allows you to achieve a smooth surface."
The next stage is to check all of the flashings around the perimeter of the roof to make sure they are solid with no delaminations. Check to make sure the flashings are still flexible and pliable. "Most leaks occur at the flashings," says Salazar, "So you can extend your roof by keeping an eye on them." If the flashings need repair, this is usually done with asphalt flashing cement. There is the standard version or the newer SBS rubber, which has the additional benefits of pliability because of its elongation properties, ability to stand up to any weather condition and resistance to ultraviolet light. "Take a special look at any curves caused by air conditioning or pipes," Salazar says. "Make sure they are all properly flashed, with no leaks in the area." Once all of the repairs have been performed, apply a reflective coating to the entire roof surface.
This has several advantages. The reflective sur-face reduces the expansion and contraction of the surface, thus lowering stress. These coatings help save energy by reducing the external temperature and lowering the temperature inside the building. And, once a roof has been coated with this reflective material, leaks and ruptures become much easier to spot.
One option for reflective coating is aluminum. This can be either water or solvent based, can be applied in a single laborsaving process and has the widest range of options for obtaining a Class-A fire rating. Acrylics have certain limi-tations. They must be applied if the temperature is 40 degrees or higher, and some manufacturers have substrate limitations that this coating can be applied to. For instance, polymer is used for specific stress conditions, and its grease resistance makes it suitable over kitchen areas.
"Check around with different coating manufacturers to make sure you are getting what you need, and you're getting the best price," advises Salazar. He makes a similar recommendation in terms of determining whether you need a new system or preserving your current system with coatings. "Go back and forth between the two, and ask questions. That's the best way to make sure you get what you need and want. "
When you think of a roof, you naturally think of a hard material. What the Mount Airy, N.C.-based NCFI offers ends up hard but starts out as a polyurethane spray. It represents one type of roof repair with some options. "A great deal of work and money can be saved by simply applying a second membrane over an existing roof system," says Marketing Manager Steve Loftis. He explains that when an existing roof has completed its service life, instead of removing it, many times the poly-urethane can simply be sprayed over it.
Advantages, Loftis says, include stopping any existing leads by providing waterproofing. Also, where an existing roof may have developed sags or low spots, this type of spray can improve drainage. For the spray can be built up in a rise of one to two in. to provide a slope. And polyurethane is a high insulating material and an ultra-violet light barrier. This type of roof is also used in new construction. It has to be applied with the right weather conditions — dry — though this is true with most systems. Loftis says polyurethane spray is priced competitive, with other types of roofing.
Another type of roofing is single-ply PVC, offered by Duro-Last Roofing, Inc. of Saginaw, Mich. Unlike the traditional BUR roofs that were actually manufactured on the top of the building, the PVC is made in-house. "The seams are actually melded together so that once it's instaIled, it's a single monolithic piece," says Marketing Director Mark Sitter. "You don't need power systems heated to 450ºF, you don't have to cordon off an area, the installation is not disruptive to classes and there are no obnoxious odors."
Another benefit, says Don Deal, national sales manager, is that the system is modular. It can be applied in sections — one part now, another a year or two later according to need or budget. "The roof is extremely reflective, so it reduces the need for air conditioning." This roof also can constitute a new system or, in many cases, simply overlay the current system. This roof is long -lasting and doesn't need maintenance, Deal says, who adds, "This roof may or may not cost more than other roofs, but it's important, for any roof, that you don't just look at initial costs. Look at the entire life-cycle costs."
"Our forte is the flat or nearly flat roof," Sitter says. "We do not require a slope. With our system, there can be ponded areas. This might not be a good building practice, but it won't hurt our system."
One reason why this roofing is used on flat or relatively flat surfaces is that it has a more utilitarian look. It's often used to cover flat spaces while pitched or gabled systems are used in other sections where there is a desire for more aesthetic material.
Firestone Building Products, based in Indianapolis, produces a variety of roofing products, says Mark Munley, division manager of Corporate Marketing. One is called a
Polylso insulation board, which comes in various thicknesses — up to four in. — and is often used with other roofs. The company makes two modified asphalt roofs, APP and
SBS versions, which Munley says are similar to the traditional built-up roofs except they are made at the plant, as opposed to on top of the building.
He adds that Firestone also makes a thermoplastic roof, which has a white reflective membrane, plus metal roofs and EPDM or rubber roofs which Munley says, "are easy to repair, like a bike tire." There are a number of other kinds of roofs, which, whether used singly or in conjunction with others, work pretty well. Most manufacturers also do a pretty good job of telling you just what their products can do. But to find the roofing that works best for your school, you're going to have to shop and compare.
By Thomas G. Dolan (pen name)