Is the roof on your commercial property getting near the end of its lifespan? With so many different types of commercial roofing materials available to you on the market, choosing the one that is right for you and your business can be an overwhelming task. There are several different factors that go into determining the right roof type to install on your commercial building, but where do you even start?
Here at RoofCrafters, our commercial roof inspection team has been assisting property owners for over 28 years with commercial roofing services. Our team is here to help commercial property owners like you make great investment decisions, whether it’s with a new commercial roof installation, or a commercial leak roof repair, we’re here to help.
When deciding what type of commercial roofing we specify for our clients, the first step is performing a commercial roof inspection. Since we won’t be inspecting your commercial roof today, the least we can do is share our 28 years of experience with you.
That being said, by the end of this article, you’ll better understand:
The different types of commercial construction roofs on the market
The 4 factors used to determine the best type of roof for your business
The top 5 commercial roofing types
The advantages and disadvantages of each of those roofs
Grab your notepad, and let’s get started!
Types of Commercial Roof Construction
There are 3 main types of roofing construction for commercial buildings.
Flat roof commercial construction
Low slope commercial construction
Steep slope commercial construction
Flat roof commercial construction is very common because it allows the engineer and architect more options for mounting rooftop equipment. With the newer roof systems today, this type of construction requires your local commercial roofing contractor to slope the roof with insulation so that there is no ponding water. The tapered insulation will provide the building a better R-value and create positive water drainage but it will also impact the overall cost of the project.
Low slope commercial roofing is when the architect has designed the commercial building so that the roof already has a positive slope to drain the water from the rooftop. The downside is that this is not always good for all the materials, for example, a low slope roof that has metal installed is typically not the best option and will result in leakage and maintenance issues that another system would not have on a low slope roof.
A steep slope roof on a commercial property is identical to or very similar to residential construction. The most common construction types on steep slope commercial roofs are gable roofs or hip roofs. These are constructed with metal or wood trusses or can be custom framed with wood 2x framing material.
4 Factors Used to determine the type of commercial roof to install
The length of warranty or lifespan that you desire is one of the factors that will help determine the type of materials to use.
Next is the durability needed, how much equipment is on the roof? So, are mechanical contractors accessing the roof to service rooftop equipment? HVAC units, rooftop vents, or satellite systems. Does your commercial roof get little foot traffic or does it have a lot of this type of foot traffic?
This will help us determine the type and thickness of the commercial roof material that will be best for your building.
Energy efficiency has been a very hot topic in commercial roof services over the past several years. Most government roof projects require a minimum energy efficiency rating on the insulation and overall commercial roof system rating.
This is something to consider when replacing a commercial roof system, does the roof system need a better R-value. The R-value is the thermal resistance of the roofing type and the insulation. The higher the R-value the less the heat from the sun's rays will penetrate the roofing into your building.
And lastly, cost, which most of us, me included, typically put first. I intentionally put the cost of your commercial roofing installation last because in order to come up with the cost we first need to have answers to the other 3 factors that will all impact the cost of the project.
Now that you know the 4 factors we use to determine the type of roof system we recommend, let's dive into the Top 5 types of commercial roofing advantages and disadvantages.
Top 5 commercial roof types
Single-ply roofing (TPO, PVC & EPDM roofing)
Modified Bitumen (rubber roofing)
Built-up roof (hot tar roofing)
Metal Roofing (standing seam & screw down)
Asphalt shingles (upgraded shingles)
Single-ply roofing (TPO, PVC & EPDM roofing)
Single-ply roofing is one of the most popular roofing materials used on commercial and residential flat roofs. They come in different thicknesses or you might hear your local roofing contractor ask “do you want a 45 mil or 60 mil roof?”
The higher the number the thicker the product. The thicker the product the longer the manufacturer warranties the flat roof material.
Single-ply TPO and PVC roof is made up of 3 layers. A base layer, the scrim layer(reinforced woven fiber layer), and thickness over the scrim layer, which is the top layer. This top layer protects the scrim layer from the sun’s harmful UV rays.
An EPDM roof typically comes in a 45 or 60-mil thick membrane. The difference is the laps and flashings on this commercial roofing material are glued or seam taped together instead of hot air welded like the TPO or PVC single-ply materials.
The advantage of single-ply roofing is they come in white which makes them heat-reflective and energy-star rated. They’re also lightweight, fire-resistant, provide a high wind rating, and are resistant to chemicals and pollutants which can be important in commercial and industrial roof applications. Single-ply roofs are also easily repairable and to keep maintained.
The disadvantages of single-ply roofs are they are not the most aesthetically pleasing roofing to look at. High foot traffic could pose a threat if the contractors are not mindful when performing work on the roof, dropping hand tools or screws and walking on them could puncture these roof systems.
Modified Bitumen (rubber roofing)
I like to say a Modified bitumen roof is the second generation of commercial flat roofing. Built-up or hot tar is the OG of the flat roofing world and we will discuss that next. Mod-bit became popular because unlike the hot tar roof that requires setting up a hot tar kettle. That job alone, heating asphalt onsite to over 500 degrees is a full-time and dangerous job. The roofing industry has slowly been moving away from hot tar roofing. Modified bitumen roofs can be installed with hot tar but the most popular installation methods are without the hot tar.
Here are 4 main installation methods.
Hot tar applied
Cold tar applied
The last 3 installation methods made modified bitumen roofs much more efficient for commercial roofing applications.
The advantages of Mod-bit roofs are they have multiple layers and having multiple layers can make them more durable. This increased durability can make the mod-bit a better choice for commercial roofs with high foot traffic.
The disadvantage of Mod-bit with these multiple layers is the cost of the materials and labor to install multiple layers is more expensive. Also performing repairs and maintenance on mod-bit roof systems can be more difficult, also increasing the cost.
Built-Up Roof (hot tar roofing)
Layering the materials is how it got called a built-up roof. The roof is built-up by layering plies of fiberglass rolls of roofing and hot tar between each layer. And this is only the short explanation of how it gets installed.
The basics of a hot tar roof so to speak. It’s asphalt heated up to 500 degrees and then we mop that directly on the roof deck or insulation. Yep, just like you would mop a kitchen floor. And in-between mopping we roll out layers of roofing while it's still hot. Many built-up roofs are done with 4, 5, or 6 layers of roofing.
The top layer is the most important layer when it comes to maintenance. It will be what determines if it can be repaired and maintained successfully. Oftentimes the top layer is a flood coat of hot asphalt (tar) with rocks put in the tar while it is still 450 to 500 degrees. A hot tar roof with a rock finish makes for a challenging repair for a very experienced roofer. But it can be done if there is useful life left in the flat roof system.
Now, if it has a granule surface cap sheet as a finish layer or an asphalt flood coat, it is much more manageable to maintain and repair. Either way, the existing materials that will need to be maintained need to have some useful life left to make any repairs that will last any length of time.
The advantage of a built up roof system is they last 20-30 years. They are very durable, so heavy foot traffic will not damage this roof system.
The disadvantage is the cost, having to install multiple layers means we roof the building multiple times to get one roof system. Heating up asphalt and pumping it up on the roof is also a very dangerous job.
Standing seam is a concealed fastener metal roof system and screw-down is a metal roof with an exposed fastener through the metal roofing. Both metal roof systems have their own advantages and disadvantages.
The advantages of the standing seam are their longevity, properly installed they will easily last for 50+ years, they provide a very high wind rating, they don't blow off in wind storms, they look great, and add value to a building. The disadvantages are they cost more because the attachment method takes longer to install and requires a much higher skill level to install all the flashings for this system.
The advantages of the screw-down roof are they are economical and provide curb appeal. The disadvantage is they require maintenance within the 5-year mark. With all the expansion and contraction(thermal movement) that happen with all metal roofs, the exposed screws can come loose.
There are 3 metal roof materials that are commonly installed in businesses in the US over the past 30+ years:
These 3 metal roofs are the most economical and cost-effective. They offer a wide range of aesthetic looks, longevity, and price ranges.
All of these materials are available in a standing seam metal, screw-down, and even a shingle-style profile.
Aluminum metal roofing
Aluminum is one of our most natural energy-efficient metal roof materials available. Aluminum metal comes in different thicknesses and typically for roofing we use a 032, 040, or 050 thickness. The higher the number the thicker the aluminum roofing will be. The 032 and 040 thicknesses are most popular on commercial roofs. Aluminum comes in a mill finish or a painted finish. Mill finish will provide you with a raw metal look and it will oxidize into a naturally beautiful raw metal finish. Aluminum comes in a wide variety of painted finished colors. Most of the paint finishes come with a 40-year paint warranty with some manufacturers even providing a 45-year paint finish warranty.
Steel metal roof
Steel roofing is the most popular metal roofing material used for roofing on commercial buildings. Steel metal is galvanized steel that is hot dipped or coated in a zinc coating. Steel is less costly and can be as effective and efficient as any of the other metal materials that are available.
The steel most commonly used for roofing comes in 24 gauge, 26 gauge, and 29 gauge. Don't get fooled, unlike aluminum, the lower the number the thicker the steel roofing will be.
4 of the most common steel roofing profile that is installed on commercial properties:
Standing seam metal panels (12”-18” wide panels, concealed fasteners)
Interlocking steel shingles (slate or shake look, concealed fasteners)
5-V crimp metal roofing (2 foot wide panels, exposed fasteners)
R-panels or multi-rib panels (3 foot wide panels, exposed fasteners)
Because steel is not a non-corrosive metal, these metal roofing materials require a painted finish. Paint finish warranties range from 20 years to 45 years depending on the thickness, type of panel, and the manufacturer of the metal.
Steel metal roofing is very cost-effective and offers a wider range of prices depending on which profile you choose, the thickness of the metal, and the paint warranty.
Galvalume metal roof
Galvalume metal is also a metal that has a steel core and is coated with aluminum to prevent corrosion.
Galvalume is much like steel roofing and comes in the same thicknesses, 24 gauge, 26 gauge, or 29 gauge. It is also available in all 4 of the different panel profiles.
The main difference with galvalume is that it comes as a mill finish metal product, so it is not available in a painted finish. This makes it slightly less expensive and easier to work with as the painted materials can get scratched during installation if not handled carefully. It is also a great option to use around the ocean or if you live anywhere near to saltwater.
Asphalt shingles (upgraded shingles)
Yes, even though shingles are most commonly used on residential homes, probably on your home and definitely on mine. Well, asphalt shingles are commonly used on commercial buildings too.
Typically the shingles installed on commercial buildings are not the basic builder grade shingle that is used on new construction homes either. The reason is that builder-grade shingles provide the least wind protection and they require replacing as early as 10-12 years.
Upgraded shingles or designer shingles are more popular on commercial buildings. The reason is they give you greater wind protection, provide better curb appeal and upgraded shingles can last 25-35 years. The disadvantage of shingles is they don't last as long as the metal roofing and when it is time to replace the roof, it can be a messy project.
What is the right type of roof for your commercial building?
If your commercial building needs a roof replacement or you are considering what type of roof to use on a new construction project here are some things to consider:
Exposed to grease, chemicals
Exposed to high winds
Visibility of the roof
The use of the building and the climate you are in should help in determining the right roof for your commercial building.
We want to help you feel comfortable knowing that you made the best decision on your next commercial roofing investment.