All three of these roofing types consist sheet of material that is normally installed over an insulated board. They can be mechanically attached, ballasted with gravel, or fully adhered which is our preference. Differing thickness’s and attachment methods can make the difference in the life of the roof. We only install 60mil membranes or higher, unless the expected lifetime of the roof is under twelve years, and then it’s okay to use 45mil. Typical base boards are PolyISO (R-6 per inch) or Densdeck which is fire rated and puncture resistant.
EPDM (aka Rubber) comes in very large sheets, but the most common is 10’x100′. It’s usually black, but white sheets are available at a premium price. Their has been many failures with EPDM roofing, mainly because of bad seams and incorrect attachment methods. With a good installation, small problems are easy to repair. The great thing about a rubber roof is that as long as you use a 60mil or thicker membrane, servicing the seams after 15-20 years will extend the life of the roof another 50-80 years.
TPO is a thermoplastic roof that is now the #1 commercial roofing type in the US. It’s cost effective like EPDM, but the seams can be hot-air welded like PVC. Seams that are welded together are actually stronger than the field of the sheet, and effectively create one giant sheet over your building. TPO is normally white, but comes in tan or gray. TPO has less of a carbon footprint during the manufacturing process, and is recyclable after it’s service life. This is why it’s known as a truly “Green” roofing option. It’s most common size is 10′ wide sheets, but is available up to 12′ wide x 100′.
PVC is a white roofing system that has been proven to be most effective, depending on the manufacturer and the installation. It can be welded to itself like TPO, but isn’t as nice to the environment during the manufacturing process. Its most common use is on restaurants and manufacturing facilities because of it’s resistance to fats and chemicals. It is great for most applications, but the material cost’s are 20-40 higher than TPO. It is the longest lasting track record, some installations are over 30 years old without any issues. This is the best option if you have ponding water, and want the most service life for your dollar.
We are factory authorized installers for GACO. Silicone is a wonderful system when used in the right case. Silicone is impervious to ponding water, which is a major problem with acrylic coatings. Silicone can be installer over EPDM and other single ply membranes, modified bitumen, and SPF roofs. The biggest part of installing a coating is preparing the surface for it, it’s not just painting a roof white. Most folks who inquire about a roof coating have waited too long and the roof needs torn off. If your roof has approximately five years of life left, you should be looking in to a coating soon!
BUR is the technical term for hot asphalt roofing. It is made up of layers of felt with asphalt between and over the top. It should be topped with gravel or an aluminization topcoat. This is a very good roof system when done properly.
Modified bitumen is a rolled product that can be it’s own system or installed over the top of a built up roof to make it last without additional coatings. It’s got a surface that resists UV rays, some are granulated where others are smooth. It can be installed using hot asphalt to adhere it, torch down, or cold-process adhesive. Modified bitumen is very resistant to puncture. It’s service life is 10-30 years depending on installation and maintenance. It can be coated to extend it’s life.
SPF is a wonderful product, but is very hard to apply. We have seen more bad installs than good by a long shot. This picture to the right is less than nine years old and has many water puddles trapped underneath the surface. It can be a decent system, but the installer must be very good at spraying the coating evenly and proper preparation is crucial. Even then, the acrylic coating will need a coating after five to ten years depending on the thickness. GACO coating can be installed over foam and offer up to 20 years of protection, which is a service we offer if the SPF is in suitable condition. SPF’s main draw is that it has great insulation properties, but the same level of insulation can be achieved with single ply membranes over insulation boards.
Most buildings have a slight slope to them, but others are dead level flat or worse. The manufacturer suggests having 1/4″ per foot slope to keep water draining. Although it’s sometimes unavoidable to have standing water, tapered insulation greatly reduces it or eliminates it all together. Ponding water can cause structural deflections, which are only going to get worse on a wood structure. To the right, we added 1/4″ tapered insulation to this church roof and it still had some standing water due to deflection. I would have really liked to seen it holding water before we tore it off, it would have been an official “pond.”