At E.S. Construction, we provide a wide range of solutions for new and existing roofing systems. With so many options to choose from, it can often be challenging to find the right type of system for your specific industry or business. Our goal is to educate all of our clients and help them choose the best roofing system for their particular needs. We’ll show you the benefits and downfalls of the types of roofing systems available and help you select the ideal application for your specific project.
About half of low slope (or flat) roofs in the U.S. are created using a single-ply roofing technique. This is due in part to the relatively minimal equipment cost and experience required by the contractor, as well as the relatively low material cost. On most sheet systems the cost of the sheet is only 25% of the total bid.
The most common application to solve issues is over tar or tar-and-gravel roof systems. It is also not unusual for contractors to install new single-ply systems over other single-ply roofs as they deteriorate.
Sometimes single-ply systems are installed over metal roofs, but the experts at E.S. Construction do not recommend this particular application. For singly-ply over metal to work properly, boards must be screwed or glued down to fill the flute, insulation boards have to be installed over that, and then the single-ply sheet is installed. This creates thousands of new holes with only a thin layer of material keeping water out. Thus, the chances of leaks occurring with this particular system are extremely high.
In layman’s terms EPDM is called a “rubber” roof because it is usually made of black vulcanized rubber, like the old car or bicycle inner tubes. These systems are designed to work in one of three ways.
The first is to lay insulation boards on top of the roof deck with the sheet placed directly on top of the insulation board. They are held down by what is called ballasted material (usually river rock) weighing up to 8-12 pounds per square foot depending on code requirements.
The second application involves mechanically fastening the insulation board to the rubber sheet with screws and plates at least every two feet (depending on wind uplift ratings) in addition to the screws that are holding down the sheet itself.
The third system is called fully adhered or glued in place. In this application, the insulation board is usually mechanically fastened and the EPDM sheets are adhered with slow-rise foam or other adhesives.
While there are significant cost advantages to EPDM, there is also a downside.
EPDM systems can shrink as much as 5-7% per year. This causes pulling on the edges of the building which in turn causes termination bars, parapet walls and side walls to be pulled out. Seams are pulled apart and vent pipes pulled over, among other problems.
Our team often sees screws back out of the roof deck and poke their heads up through the sheet itself, creating holes through which water can seep. Weather cracking can also be caused by huge temperature fluctuations, making the sheet brittle after several years. We’ve also seen wind damage occur to EPDM roofs, especially prevalent on ballasted roofs.
Lastly, the seams of EPDM are sealed with a water-soluble glue that can cause seam failure over time.
Thermoplastic Olefin (TPO) is a relative newcomer to the single-ply market. TPO was designed to replace EPDM at the low end of the market because PVC’s are typically higher in cost than an EPDM roof. The overall performance for TPO is generally in between EPDM and PVC. TPO’s are popular because of pricing, but have yet to prove their durability over long extended periods of time like some other systems.
Hypalon systems are proven to be the best of the sheet systems on the market today, because it cures on the roof and does not become weak and brittle like other single-plys. It can be held down using ballast, mechanically fastened, fully adhered or held in place with negative air pressure. Hypalon sheets are also heat-welded at the seams. They are chemically resistant and are ideal in cases where chemicals may be deposited.
However, as with all single ply systems, once a hole is created, water is free to migrate anywhere.
Spray Polyurethane Foam (SPF) is applied using a special spray gun that mixes two chemicals as they exit the barrel, causing a chemical reaction that produces foam. Foam is usually applied in thicknesses from one inch to several inches. Polyurethane foam is a plastic which is waterproof after it is applied. However, it needs protection in the form of a top-coat or layer of rock to resist UV rays in sunlight and keep it from deteriorating.
SPF can be made as soft as a pillow or so hard that you can drive a nail into it. Foam used for roofing allows expansion and contraction of the roof but withstands high foot traffic, impact, wind and weather. Foam is flexible and can go over different substrates with ease.
As a roofing material, SPF is difficult to beat if good quality coatings are used and properly applied. On the other hand, if substandard equipment is used and the ratio between the chemicals is incorrect, it can cause bubbles in the foam. The same problem can occur from applying roofing over a wet substrate. Roofing contractors should apply SPF to a depth of no less than 1 inch, recommended by Society of the Plastics Industry (SPI). Certain contractors will attempt to skimp and only apply a half-inch or less, only to have the roof blister & fail prematurely.
Among the advantages to SPF is that it creates a continuous seamless membrane, with every square inch fully adhered to the roof deck. Thus, if a puncture is created in the coating layer it will not create a leak. Even when a hole made clear through to the roof deck, a leak may not occur because foam is fully adhered. SPF roofs are also referred to as a renewable roof systems – even if the roof has gone too long without attention, bad areas can be cut out and reformed, and settled areas can be filled in with more foam.
The big saving In SPF roofs, however, comes from energy efficiency. Each inch of foam roof has an R-value of around 7, and the roof surface is white which helps reflect sunlight and make the roof cooler. Most SPF systems pay back the cost of the roof in energy savings alone within a few years.
And years down the road, the cost to re-roof over SPF will be substantially less expensive than roofing over other systems.
Metal roofs wear out over time because of a number of things happening to them. The neoprene washers wear out, the holes around the screws become oblong due to the expansion and contraction of the metal, or the mastic that is put between the sheets gets hard and cracks. Skylights and seals around penetrations are also a common cause of metal roofing failures.
The system that E.S. Construction uses to correct the above problems is called the MR-system. Our crew power washes the roof, tightens and adds screws where needed. Patches are made to bad sections of rusted out portions or breaks in the tin. We then apply an inhibitor primer to the rusted areas of the roof.
In cases of extreme rusting, this primer is applied to the entire roof. We then apply fabric and coating to the vertical and horizontal seams, as well as the penetrations and skylights. Screws treated with a fastener-grade caulking are inserted and tightened. Finally, the entire roof is sprayed with a white coating, making the entire roof seamless and waterproof.
Cons of this system:
Some contractors use cheap coatings which will not last on the roof. Others get brittle with age, turn chalky, or get hard. Due to product or application errors, the coating can’t stand the amount of stretch required and cracks appear on the seams which cause system failure.
Pros of this system:
Coatings over existing metal roofs prevents any additional holes in the roof. This system is lightweight and turns the roof white, thus reducing internal temperatures by 10-15 degrees. A new metal roof doesn’t come with a “leak free” warranty. With our MR-system, you can get a 10-year leak free warranty on material and workmanship. The MR-system also doesn’t interrupt the work of the building being roofed. And you’ll be saving up to 1/3 to 1/2 of the costs than other alternative roof systems (single ply, new metal roof, foam).
Roofing Choices You Should Always Avoid
Metal over metal or metal over BUR is when a new metal roof is placed over or replaces an old metal roof or BUR. Today, material and labor in constructing buildings is not of the same standard as buildings put up 20-30 years ago. The screws are put in by electric drills, which may not be set property and screws may be over tightened.
All of this put together makes for less than quality work. And while the roof may come with a 20-year warranty on the building, read the fine print. This type of application does not result in a leak-free roof. Other companies will come out for about a year and put caulk on seams and perform other tasks to show good faith. But ultimately, this proves to be a major hassle and costly expense for most businesses.
Tar roofs have been popular from the very beginning of the commercial and industrial roofing industry. These kinds of roofs were being put on buildings before man ever walked on the moon and the process has not changed much since then. Furthermore, the tar used today does not live as long as the tar used decades ago due to EPA regulations.
Another issue with tar roofs is that the conditions necessary to perform the work needed is difficult and strenuous. On a 90 degree day in the summer working on a black surface around hot tar, it is very possible that the roof temperature is 150-170 degrees.
These systems which used to last 20 years are now only lasting 10 years. And once they wear out, you have to replace them – which is very costly. And unlike a variety of other options on the market, tar has no energy efficiency.
This is the roof system that quite literally “sets the roof on fire.” An attempt to modernize the tar industry, companies combine tar and rubber emulsion and blend them together to make a hybrid roof system. They accomplish this by heating the sheet to the point of melting with blow torches and essentially gluing the sheet to the roof.
Three major problems occur with this process. First, wherever you have fire on a roof, the fire can get out of control. The seams tend to be a weak spot of this system causing roof failure. And lastly, when the sheet fails to heat to the proper temperature, it doesn’t sheet adhere to the roof which causes bubbles.
Questions regarding a specific system? Get in contact with E.S. Construction by sending us a message or calling us at 866-647-4644.