A flat roof is the best system for a large sized commercial building. Installing a sloped roof on such a property doesn’t work, because it will be much more difficult and expensive. You will also need architectural engineering to handle the additional weight, as well as any rooftop HVAC equipment and drainage.
One of flat roofing’s best features is that it can also be as a deck, a green roof with rooftop vegetation, a large patio or even a penthouse. Green building backers prefer them, because of the rooftop rooftop vegetation option, which can improve air quality and reduces the heat island effect in large cities. If you are planning on installing a green roof, you’ll want to use 80 mil or thicker PVC or TPO membranes, because hot-welded seams will ensure the roof won’t leak underneath the soil and plants.
Another advantage is flat roofing works best in instances where large heating & cooling equipment needs to be installed. With a flat roof. the equipment go up on the rooftop, instead of having to be installed on the ground.
Lastly, flat roofs are excellent for large-scale solar panel installations, as they are not shaded, allowing them to get maximum sun exposure throughout the day.
Here are Some Advantages of a Commercial Flat Roofing System:
PVC is the longest lasting material. Because of its heat-welded seams, it stays flexible during its lifetime and will withstand thermal movement. A PVC roof can last well longer than 30 years. Manufactures usually offer a 25 year warranty for commercial installations and some offer LIFETIME warranty for residential.
EPDM will last about only 10-15 years. Even though manufacturers offer warranties that are up to 40 years for commercial flat roofing, you need to be aware that these warranties don’t cover failing seams or ponding water. Remember, both of these are the main causes of failure for a rubber membraned roof.
The average lifespan of a TPO roofing system varies a lot because of issues with membrane’s formulation. Currently, they range from 7 to 20 years. Manufacturer warranties are up to 20 years for commercial TPO installations.
Remember that warranties offered on different types of single ply membranes vary highly depending on thickness, size, method of installation, and environmental conditions. You should carefully read and compare warranties for different materials you are considering.
Tar & Gravel, along with Modified Bitumen roofs last between 10 and 20 years, but are costly to remove and tear off at the end of their service lives. How long they last depends a lot on the installer, because there aren’t many roofing contractors still around who actually know how to work with this material. If you have this type of roof and it needs to be repaired, your best bet is to call on a professional who has experience with it; someone who specializes in single membrane roofs won’t be a very good choice.
The most common signs you will see when your roof starts to deteriorate are:
– Thinning and blistering
– Slice marks
– Contractions or pulling
– Grease and dirt build-up that can’t be removed
TPO and PVC are both highly reflective, with up to 90% of heat sent back into the atmosphere. This means that either of these systems will save you hundreds of dollars on your utility bills. Both are Energy Star Rated for their cool properties.
One thing to note, however, is that white colored roofing systems collect a lot of dust and dirt over their lifespan. Over time, this will lower their energy efficiency. But, they still remain very reflective. Consistent, regular maintenance will help prolong the optimal energy efficiency of a white membrane roof.
Recently however, many darker color membranes have been developed and formulated to have light-reflective properties and offer utility bill savings. You should check the manufacturer’s specs on a particular product to review its energy efficiency ratings.
Modified Bitumen and EPDM have the lowest energy efficiency rating. In fact, because they are dark in color, they can heat up as high as 170 degrees in the summer months, which would make your cooling system work over-time and run up larger energy bills.
Both TPO and PVC are completely, 100% recyclable. At the end of their lifespan, the old membranes can be recycled back into making new ones.
Its also possible to install PVC over an older roof, which would eliminate tearing it off, cutting costs and saving landfill space in your community.
On the other end of the spectrum, EPDM, Tar & Gravel, Modified Bitumen are not very environmentally friendly. They can’t be recycled, because they are made from petroleum based materials. Because of this, their torn off materials have to be disposed of at a landfill.
Repair & Maintenance
PVC membranes are easy to maintain and repair. Their heat-welded seams can be re-welded throughout their lifespan, making any repair, maintenance or modifications needed to install new equipment quick and easy.
A heat welded membrane, like TPO or PVC, typically consists of welding a patch on the membrane over the hole or puncture thats been found as the source of a leak, or if its a void in the seam, simply re-welding it.
If there are no leaks, you should still re-seam (applying a 6 inch cover tape over all the seams) an EPDM rubber every 7-10 years, which is the period of time that the adhesive naturally starts deteriorate. The repairs are done using EPDM peel & stick flashing + EPDM primer (which is the recommended way) or by using older black glue. Penetrations or punctures are repaired using uncured flashing that is stretched to form around the angled surfaces.
The Importance of insulation
If you’re planning to install a new commercial flat roof or replace an older one, its critical to install high-quality insulation, with the appropriate R-value. If you don’t, you’ll waste a lot of money on heating and cooling costs. You will also have temperature fluctuations inside your property.
We recommend you consult with your commercial roofing contractor to figure out what type of insulation will work best for your building, and how much of it you will need.
Its not a wise idea to try to save money on insulation. It will only result in a lower service life of your roof, poor energy efficiency, as well as uncomfortable temperatures inside your property. Most likely, you will end up spending more money to fix insulation problems, which could have been avoided from the start.
Durability and Maintenance Issues
Leaks and Moisture
The biggest issue for most of these roofing systems is the presence of seams and flashing, because those are the main areas where leaks happen.
PVC and TPO are the only two membranes that have hot-welded seams that don’t come apart, and thusly, don’t let any moisture penetrate.
Tar and Gravel, Modified Bitumen and Rolled Asphalt offer extremely inferior protection against leaking and ponding water.
EPDM rubber typically fails at or near roof penetrations, along with flashing and seams, allowing water to penetrate.
One of the biggest problems with spray-on roofing systems is the insulation can be destroyed by birds, therefore also resulting in leaks.
Resistance to Punctures
Built-up roofs are usually 0.5 + inches in thickness, and the materials they’re constructed of are pretty hard and difficult to puncture.
Single plies and spray foam roofs are generally pretty easy to puncture by direct contact with a sharp object.
Some PVC materials come with a fiberglass reinforcing cover, which makes it difficult to puncture.
Remember that increasing the width of a single ply membrane DOES NOT improve its ability to protect against leaking, However, it will extend its overall lifespan, and make it much more puncture resistant.
At Armadillo Roofing & Exteriors, (512) 333-7663, we provide commercial flat roof repair and commercial flat roof installation services to Waco, Texas and all its surrounding communities. We have been providing commercial roofing services to the area for over 15 years. When you need experienced, professional repairs on your commercial flat roof, give us a call.