Choosing the Right Flat Roofing System for your Building

There are several roofing systems on the market to choose from and almost unlimited ways in which each one can be installed. So, how do you choose? You need to be able to make an informed decision, and not just rely on the opinion of the contractor providing the estimate.

The first thing to contemplate is the slope of your roof. The National Roofing Contractors Association recommends ?” per foot taper for all roofing systems. Roofing systems without a slope tend to hold water. Any roofing system that holds water will not last as long as one that drains well and does not pond water. Ponding water is defined by the National Roofing Contractors Association as water that is on the roof forty-eight hours after the last rainfall. If your buildings roof is flat, when it is time to replace the roofing system it is a good idea to install tapered insulation to improve drainage.

The second consideration is the weight of the roofing system. Not all buildings can handle a lot of weight. Besides the weight of the actual roof, you must also consider snow load, dead load and live loads on the roof. It is a good idea to have a structural engineer inspect your building to determine whether the building can withhold the weight of the roofing system you want to have installed. In most cases the cost will be only a few hundred dollars, which is considerably less than what it could cost if the roof collapsed. A fully adhered membrane roof weighs approximately one to two pounds per square foot; a built-up tar roof about seven to nine pounds per square foot and a ballasted membrane roof will weigh around eleven to sixteen pounds per square foot. Note that these weights will vary for each roof and should be looked into each time you have a roof system installed.

The amount of traffic on your roof will also need to be considered. The tar roofing systems on the market are some of the best for handling roof traffic. If you choose a rubber or thermoplastic roof, a reinforced membrane is a good choice because most manufacturers offer a puncture resistance warranty that will cover leaks even if you put a hole in the roof. No matter which system you decide to have installed, walkway pads are recommended for areas that will have traffic.

Another item to take into account is the wind load on your roofing system. If you are in a high wind area you will need to install a roofing system that can handle the higher-pressure wind puts on a roof. You should check with your insurance carrier, to find out what requirements they may have as to the types of roofing systems they will allow you to install and remain insured. It’s also a good idea to check with the manufacture about wind loads, and the roofing system you may want to install.

You will also need to become familiar with state and local fire codes. The use and occupancy of your buildings will determine whether you need to meet Class B or Class A fire codes. Certain situations such as senior housing or apartments require meeting the Class A fire code. Your insurance carrier should be able to assist you in finding out what fire codes you must comply with for your building.

Additionally you will want to consider the color of the roofing system. If you are able to see the roofing system, the color may matter to you. Other than aesthetic value, color also has an effect on the heating and cooling of your building. A white or lighter colored roof may keep your building cooler in the summer thus reducing the cost of cooling your buildings. A dark colored roof absorbs the heat from the sun, increasing the costs of cooling your building in the summer but reducing the costs of heating your building during the cooling months. Also to get the full affect of the light colored roof you will need to clean your roof every couple of years because of settlement build up. Consider the climate in which your building is located, in Minnesota we spend more time heating our buildings than cooling them.

Finally, look at the cost of the roofing system. Every year dozens of roofing systems are replaced within the first five years because the wrong system was installed. Bottom line is that the correct roofing system, properly installed should give you a roof that will last thirty years or better.