After more than 18 years in business, we’ve encountered a wide variety of roofs on commercial buildings. Whether it is a metal roof, tar & asphalt, or a pitched or flat roof, some are in good condition while others have serious problems.
What we’ve found is that no roofing system is ideal for all cases. At Tillotson Enterprises, we take the time to sit down and discuss all of the options with you and arrive at the best solution for your building together.
The following is a brief discussion of the pros and cons of the various systems offered by Tillotson Enterprises and our competitors.
Single Ply Roofing Systems
About half of the low slope (or flat) roofs in the Midwest use a single-ply roofing technique. This is due in part to the relatively minimal equipment cost and experience required by the contractor to install, 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 for a single-ply roof is over tar or tar and gravel roof systems as they wear out. Single-plys are also installed over other single-ply roofs as they deteriorate.
Sometimes, single-ply systems are installed over metal roofs, but this is not a recommended application. To make this work, board must be screwed or glued down to fill the flute of the metal, insulation board is installed over that, and finally the single-ply sheet is installed on top. Thousands of new holes have just been made by doing this, and now there is only a thin layer of material keeping water out.
There are a variety of chemistries for single-ply materials.
EPDM – In layman’s terms EPDM is called a “rubber” roof because it is usually made of black vulcanized rubber much 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 board on top of the roof deck. The sheet is then placed directly on top of the insulation board and held down by what is called ballasted material (usually river rock) which can weigh from 8-12 pounds per square foot depending on code specifications.
The second application involves mechanically fastening the insulation board to the rubber sheet with screws and plates that are spaced at least every two feet (depending on wind uplift ratings). This is in addition to the screws that are already holding down the sheet itself.
The third system is called fully adhered or glued in place. In this application, the insulation board is mechanically fastened and the EPDM sheet is then adhered with slow rise foam or some other form of adhesive.
While there are cost advantages to EPDM roofing, there are also significant disadvantages.
First, these systems can shrink as much as 6% 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 can be pulled apart and vent pipes can be pulled over, among other problems. Second, we often see screws back out of the roof deck due to expansion and contraction of the roof. They eventually poke their heads up through the sheet itself, making holes that water can seep through all over the interior of the building. Third is the problem of weather cracking, which is caused by temperature fluctuations that can make the sheet brittle after several years. Fourth is wind damage, which is often not noticed on ballasted and glued roofs. Over time, the wind can cause the sheet to become unfastened from the substrate. Lastly, the seams of EPDM are sealed with water-soluble glue that can cause seam failure over time.
PVC – These sheet systems are typically white or tan in color and are usually fabric reinforced to make them stronger than EPDM roofing. However, in our experience, the chemical makeup of these systems can cause them to become brittle with age. These systems are usually mechanically fastened, and although they do not shrink, they have many of the same problems as an EPDM roof: screws can back out making holes, and wind damage is not uncommon.
On a positive note, the PVC sheet is usually white, which reflects rather than absorbs the sun’s energy. The seams are also heat welded, rather than being glued, which results in a significantly stronger seam.
TPO – 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 an EPDM roof and a PVC roof.
Hypalon – Hypalon is a system that cures on the roof and does not become weak and brittle like other single-plys, which makes it one of the best sheet systems on the market. It can be held down using a ballast, mechanically fastened, fully adhered, or held in place with air pressure. Mechanically fastened is by far the most popular method. This sheet is also heat welded at the seams. Hypalon sheets are very chemically resistant and are the roof of choice in cases where chemicals may be deposited from vents or pipes. However, as with all single ply systems, once it has a hole in it, water is free to migrate.
Spray Polyurethane Foam
Spray Polyurethane Foam (SPF) is applied using a specific spray gun that mixes two chemicals as the trigger is pulled, causing a chemical reaction that produces the end product. Foam is usually applied in thicknesses from a minimum of one inch to several inches, depending on the amount of insulation value that is desired. Polyurethane foam is a plastic and is waterproof after it is applied, however, it needs protection in the form of a coating system or layer of rock to help it resist the UV rays in sunlight and keep it from deteriorating.
SPF can be made as soft as a pillow or so hard that you could not drive a nail into it. Foam used for roofing is soft enough to be able to move with the expansion and contraction of the roof but hard enough to withstand foot traffic, impact, wind and weather. Foam is flexible and can go over a variety of substrates with ease.
As a roofing material, SPF is difficult to beat if the applicator is using a high quality coating and properly applying the product. If, on the other hand, substandard equipment is used and the ratio between the chemicals is incorrect, it can cause bubbles or blisters in the foam that can potentially create problems down the road. The same problem can occur when applying foam roofing over a wet substrate. Tillotson Enterprises applies SPF at a thickness of no less than 1.5 inches, half an inch above the minimum one inch recommended by the Spray Polyurethane Foam Alliance (SPFA). The SPFA is the governing body of the foam industry. Some contractors will apply a half-inch or less which will lead to problems and added cost to properly repair.
Among the advantages to SPF is that it creates a continuous and seamless membrane, with every square inch fully adhered to the roof deck. This means that if a puncture is created in the coating layer it will not create a leak because water cannot travel through the foam. In fact, if a hole is made all the way through to the roof deck, a leak still may not occur because the foam is fully adhered at every point. Yet if the same hole were formed in a single-ply roof, the water would spread throughout the roof deck, finding any number of holes caused by the screws holding down the sheet system.
SPF roofs are also referred to as a renewable roof system because even if the roof has gone too long without attention. Any bad areas can be cut out and re-foamed, and settled areas can be filled in with more foam.
The big saving from SPF roofs, however, comes from energy efficiency. Each inch of foam roof has an R-value of around 7, and the protective coating system 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 in just a few years.
In addition, years down the road, the cost of renewing the coating system over SPF will be substantially less expensive than roofing over other systems.
Metal Coating Systems
Metal roofs wear out over time because of a number of things that happen to them which leads to water in the building. The neoprene washers on the screws or nails wear out, and the screw holes become oblong due to the expansion and contraction of the metal. The mastic that is put between the sheets along the seams will eventually get hard and crack. Skylights and seals around penetrations such as vent pipes are also a common cause of failures.
The system that Tillotson Enterprises use to solve the problems previously stated is called the Metal Restoration (MR) System. The roof is first power washed to clean the substrate. Screws are tightened and in some cases added to ensure that the substrate is secure to the building. Patches are added to bad sections of rusted out metal or breaks in the metal. A rust inhibiting primer is applied to any of the metal that is showing rust or signs of rust. In some cases, this primer is applied to the entire roof. Fabric and coating is then applied to the vertical and horizontal seams and also around the penetrations and skylights. This adds strength to the seams so that when the metal expands and contracts it does not tear the coating. Every screw is then treated with a fastener-grade coating. Finally, the entire roof is sprayed with a white coating. This white final coat makes the entire roof seamless and the complete system makes the roof waterproof.
Cons - Some contractors use cheap coatings which will not last. Some coatings get brittle with age, turn chalky, or get hard and crack over time. Some applicators try to cut corners by not using fabric for reinforcement on the seams. Due to product or application errors, the coating can't stand the amount of elasticity required, and cracks appear on the seams which cause system failure.
Pros - This system does not add any additional holes in the roof. It is anywhere from 1/3 to 1/2 less costly than other alternative roof systems (single ply, new metal roof, foam). This system is light weight and makes the finished roof white which in turn makes the interior of the building 10-15 degrees cooler. The MR system stops leaks! This may sound funny but we have roofed some new metal roofs which were under construction, and before they were even completed the roof was already leaking. The MR system solved their problems. A new metal roof doesn't come with a "leak free" warranty. We have found that if one reads the fine print of the warranty, most of the time the customer is not getting what they think they are getting. The roof may come with a 20-year warranty on the building but read the fine print. This is not for a leak free roof. They will come out for about a year and put caulk on seams, etc. to show effort to stop leaks until you finally get tired of calling or they say their obligation is up. With the MR system you can get a 10-15 year "leak free" warranty on material and workmanship. The installation of an MR system also will not interrupt the purpose of the building being roofed. The roof system can be written off in one year in taxes as "maintenance and repair", and does not become depreciated out like a new metal roof, single ply, or a foam roof needs to be.
Metal over Metal - This is where a new metal roof is placed over the old metal roof called (retrofit) or the old metal roof is torn off and a new one put in its place. This is fairly self-explanatory. There is, however, some misconceptions about this process. When we started roofing over 20 years ago, the type of roofs that we applied the MR system on were about 20-30 years old. In the last several years the age of the metal roofs that I have been doing has decreased to 10 years to not even finished. Yes, you read correctly, not even finished. Today material and labor in constructing buildings is not of the same standard as buildings that were put up 20-30 years ago. The only way that I can explain this is that the average age of construction crew workers today is in their mid-20s and early 30s and so the experience is not there. Also, the majority of today's workers are in it for a paycheck and don't have the pride of workmanship that was seen years ago. Another problem is that all the screws today are put in by electric drills which may not be set property causing screws to be over-tightened. All put together, this makes for less than quality work. Don't get me wrong, there are still good roofs put on by good crews, but I don't think you can assume a leak free roof every time. The roof may come with a 20-year warranty on the building but read the fine print. This is not for a leak free roof. They will come out for about a year and put caulk on seams, etc. to show effort to stop leaks until you finally get tired of calling or they say their obligation is up.
Tar (BUR) - These have been popular from the beginning of the commercial and industrial roof systems age. Again in my opinion these types of roofs are dated technology. These kinds of roofs were being put on before man ever walked on the moon and basically the process has not changed. Actually, this process is not even as good today as 30-40 years ago. The tar used today does not have as long of a life span as the tar used years ago. This is due to EPA regulations. Another problem is today's worker will not labor under the conditions necessary to perform the work needed to accomplish this type of job. On a 90 degree day in the summer working on a black surface around hot tar, it is very possible that the roof temperature can reach 150-170 degrees. These systems, which used to last 20 years, are now only lasting 10 years. Once they wear out you tear them off and replace them with a new one. Again, they are black, not white and are not energy efficient. Rock is put in the tar on these systems for two reasons. First is to protect the roof from the weather. This works to some degree, but it also makes finding a leak much more difficult. The second reason is to reheal itself from when the tar gets hard in cold weather and then warms up and re-melts and flows back together again. Due to regulations, tar does not have the ability to get hard and re-melt over and over like it used to.
Torch down – This roof system is often associated with stories of roof contractors burning down buildings. This system is an attempt to modernize the tar industry. Tar and rubber emulsion are combined and then blended together to make a hybrid roof system. This is accomplished by taking the sheet provided by the factory and heating it to the point of melting with blow torches which glues the sheet to the roof. Three major problems occur with this process. The first of these is obvious, wherever you have fire on a roof the fire can get out of control and potentially spread faster than anticipated. Next is that the seams tend to be a week spot of this system causing roof failure. Finally, the sheet does not always become hot enough and it does not properly adhere to the roof, which causes bubbles.
We hope this document has helped you in making your roofing decision. At Tillotson Enterprises, we offer only the roofing systems outlined on the Tillotson Roofing Systems page of this website. The two most popular roof solutions are the MRSystem and the foam roofing system. We like these because the MR system is less expensive than all other options, and the finished product, for the money, is an excellent buy. Most times an MR System could be installed improperly and still perform as well as other roofing options. The foam roofing system really offers more than we could ever put into words. When installed correctly, a foam roof is by far a superior roofing solution.
Tillotson Enterprises focuses on employing a quality workforce that shows attention to all of the details that go into creating a quality roofing application. Our employees have gone through training and certifications that allows our company to ensure that you, the customer, will be more than satisfied with the work. In a roofing season, we spend less than one percent of our time on warranty work. The people that we employ to sell our roof systems are the same people that are there to perform the application and ensure that it is being done properly. We look forward to working with you, and being the solution to your roofing problems.
