Understanding Flat Roofs
Flat roofs have some basic issues and challenges. For example, drainage can be a big problem if the slope is not right. A drainage problem can lead to water leaks and mold developing. Watertight seals are the answer to this problem. Plastic or rubber can also be used. Another option would be to use some pitched roofing along with the flat areas, because nobody wants water pooling on, in, or around their property. You need to use proven, successful methods and quality materials to ensure that your flat roof is installed properly and maintained well.
The maintenance of flat roofing on a commercial building is another issue often cited by building owners and property managers when deciding on a roofing system. Some don’t choose to install a flat roof on their building due to being misinformed. While there are legit concerns, we believe the key is to use the correct materials, installation methods and procedures for installing the roof.
Flat roofs work great in the dry, warm and windy Texas elements. Flat roofing systems use less surface area opposed to pitched roofing systems, which can have double the total square area of a flat roof. They also do a good job of reflecting heat on sunny, warm days, which helps to insulate and cool the inside of buildings too. In warmer areas, every cooling opportunity is helpful in keeping energy costs low.
Commercial flat roofs have definite requirements. Unlike sloped, pitched roofs, which rely on gravity to shed water and material from them, flat roofs use drains and rely on water resistant membranes to protect the building. The term ‘flat’ is a little misleading — no roof is totally flat or water would pool on it. “Low slope” is a better term for what’s commonly called a flat roof. Flat roofs have at least a 1/4 inch of slope per foot (or more) so that moisture can flow downhill to the drainage system and then off the roof and down to the ground.
Types of Commercial Flat Roofing Systems
In the past, most commercial flat roofs wouldn’t last as long or be quite as durable as sloped roofing systems, because sloped/pitched roofs shed rain and organic material better. Over the last few decades, however, new advanced materials have been developed for flat roofs. They’re more durable, energy efficient and will compete with sloped roofs for the length of their lifespans.
Here are the three main types of materials used on flat roofs:
3. Spray-on or paint-on
Single-Ply Commercial Roofing
EPDM (Ethylene Propylene Diene Monomer), PVC (Polyvinyl Chloride), and TPO (Thermoplastic Olefin) are the main types of single-ply membranes used.
Today, these three are the most common materials used for both commercial and residential construction on flat roofs. Its important to know that they aren’t the same in quality and longevity. They all have different formulations, durability specifications and cost.
Single-ply is simply one layer of membrane as the waterproofing and weather deflecting surface. All membranes range in width from 6 to 18 ft. The most commonly used width is 10 feet. The average thickness of the membrane goes from 45 to 90 mil. Its usually recommended to install a membrane that’s, at a minimum, 50 mil in thickness.
Commercial Flat Roof Repair Contractors
TPO against PVC
There’s a big discussion in the industry around using TPO versus PVC membranes, and arguments about which is the more effective material.
PVC is now considered to be the more durable of the two. Its specially formulated to remain intact in a varied variety of severe weather elements (rain, snow, wind, sun, hot and cold temperature fluctuations). Also, what makes PVC so solid is the fact that the top and bottom ply of the membrane have almost equal thickness.
TPO, on the other hand, has limited durability, as there isn’t any consistent specs with the manufacturers, who are testing to make it more durable, and also less costly than PVC. But, as with anything, when you try to get the price lowered by compromising the quality of the materials you’ll end up with an inferior product.
One thing that affects TPO’s durability is the top ply (weathering surface) of the membrane (which provides the strength) is actually thinner than the bottom ply. In most iterations of the product the ratio is 40/60.
Lastly, most TPO systems have poorer resistance to heat and solar overload than PVC.
Built-up Roofs (BUR)
Built-up roofing materials are constructed by using built-up layers of either tar-infused paper and liquid tar with gravel, asphalt, rolled asphalt, or modified bitumen. As the roofing system is installed, more layers are added to increase its strength and lifespan, which is why its named “built-up”. One thing to remember is that any kind of built-up material requires a more positive roof slope of at least 1/12 inches.
As mentioned, the materials BUR is made of are:
All of these methods are starting to become outdated by today’s modern construction standards. They’re not installed much on large commercial properties anymore, but there are some residential properties still using it, because of the lower installation cost compared to other systems.
Spray-on Foam and Paint-on Flat Roofing Systems
The two main types of spray and paint applications are:
Spray Foam Insulation – Sprayed directly onto the roof deck and then coated with acrylic or urethane coating, and sometimes a layer of crushed stones or sand in addition to the coating.
Paint-on Roof Coatings – Made for existing roofs and used to extend their life by 10 years or more. They are usually applied on top of single ply, modified or low slope metal roofs.
At Armadillo Roofing & Exteriors, we provide commercial flat roof repair, commercial flat roof installation and residential flat roof installation services to Round Rock, Texas and all the surrounding area communities. We’ve been in business since 2003 and have plenty of experience in all commercial roofing applications. When you need advice on repair or installation of your commercial flat roof, don’t hesitate to give us a call at (512) 333-7663.