Flat Roof Types Explained

Flat roofs have long been a staple in commercial properties. And thanks to advancements in roofing technology, flat roofing has been finding more and more residential applications. Below is a quick rundown of some of the most common types of flat roofs.


BUR (Built-up Roofing)

  • What It Is: Also known as tar-and-gravel roofs, BUR systems are made of alternating layers of hot tar and plies of waterproof material and ballasted with a top layer of gravel. Some modern versions of BURs use fiberglass membranes instead of tar paper.
  • Advantages: Cheapest flat roofing option; fire-resistant; highly resistant to heavy foot traffic; aesthetically pleasing.
  • Disadvantages: Heavy (may require additional structural support); installation produces odorous smoke and requires that a building be vacated while installation is in progress; leaks can be hard to find; gravel can clog scuppers and gutters.

Single-Ply Roofing

Single-Ply Roofing.


  • What It Is: A roof system with a single synthetic polymer-based waterproofing layer. The sheets can be adhered or fixed with fasteners, with joints between sheets sealed with adhesive, heat or mechanical means. By virtue of their construction, single-ply roofs are cost-effective, easy to install and lightweight.
  • TPO (Thermoplastic polyolefin)

    • Advantages: Highly resistant to scratches and tears; highly resistant to UV, ozone and chemical damage; leaks are easy to locate and fix; made of recycled materials
    • Disadvantages: Only available in black; additional energy-saving features can make it more expensive; prone to punctures; must be ballasted to receive a satisfactory fire rating.
  • EPDM (Ethylene propylene diene monomer; “true rubber”)
    • Advantages: Highly resistant to scratches and tears; highly resistant to UV, ozone and chemical damage; leaks are easy to locate and fix; made of recycled materials
    • Disadvantages: Only available in black; additional energy-saving features can make it more expensive; prone to punctures; must be ballasted to receive a satisfactory fire rating.
  • PVC (Polyvinyl chloride)
    • Advantages: Wide range of colors and thicknesses; fire-resistant; highly resistant to UV, ozone and chemical damage
    • Disadvantages: Not suitable for refurbishment applications; temperature-sensitive; prone to shattering and puncture in cold weather; can be difficult to repair; contains plasticizers and chlorine.


Modified Bitumen


  • What It Is: A special type of single-ply roof impregnated with a mineral-based wear surface. Modified bitumen roof systems can be hot applied (hot-mopped), cold applied (adhered), heat welded (torched seams) or self-adhered (peel-and-stick).
  • Advantages: Highly resistant to scratches and tears; easy to install and repair; performs well in cold weather; light-colored surfacing options are energy-efficient
  • Disadvantages: Fire hazard during installation; some installation methods cannot be used on occupied buildings.

Final Thoughts

Flat roofs in general are cost-effective over their lifetime and usually warranted for 10 to 20 years. And it isn’t uncommon for these roofs to last an extra 15 years if they were installed properly from the get-go and given regular maintenance.

Considering the all-important role of the roofer in installing and maintaining a flat roof, always make sure you’re working with a company you can trust. Find a local roofing contractor who is not only licensed, bonded and insured, but also has plenty of experience with the type of flat roof you want. At the end of the day, whether you go with a built-up, single-ply or modified bitumen roof, the most important thing is that you get the most out of your investment.

Author Bio

Jesse Curry is one of the key people behind Roofing by Curry, a roofing company based in Sarasota, Florida. On the job, he puts his creativity, drive and leadership skills to good use in providing quality service to all of their clients. Jesse is constantly on the lookout for ways to expand the company’s reach and sees challenges as opportunities for them to grow. Not one to ignore his passion for roofing, he regularly shares industry news, tips and company updates on the Roofing by Curry blog.



Erin Emanuel


  1. It’s important to keep an eye on flat roofs too. Water can pool easily if the roof isn’t draining properly and a leak can quickly become a big problem. If done right, however, flat roofs can be an attractive and easy option.

  2. We’re looking at moving into a new office and I thought I’d do a little research on the building, but I had no idea there were so many different kinds of flat roof types. Based on your descriptions I think ours might be a Single-Ply PVC type. I guess I’ll have to wait until we actually move into the building so I can get a better look.

  3. Nice read. Never knew there were these many options for roof. We’re planning to renovate our office building. Have fixed an appointment with Empire Roofing Corporation ( Mississauga ) for tomorrow. This would definitely come handy.

  4. I had no idea that there were so many differences in how roofs could be put together. Thanks for taking the time to explain them all – I need to get some work done, and now I have a decent idea what to ask about when I go looking for a contractor. Thanks again or sharing!

  5. I didn’t know that BUR and tar-and-gravel were the same thing, so thanks for the clarification. I like how that option is resistant to heavy foot traffic. My friend is interested in this field, so I’ll have to talk with him about what I’ve learned.

  6. Open gutters are the most common ones installed on residential roofs. These types of gutters need to be cleaned regularly in order to keep them free of dirt, leaves and other debris, in order for them to function properly. Depending on the type of roof you have , there are many different types of gutters to choose from. The most common type of gutters are steel gutters, aluminium gutters, wood gutters, and vinyl and plastic gutters, just to name a few. You should consult your local professional roofing service for advise on which ones would be the right choice for your home.

  7. Great article, I think when most people think flat roof they think tar and gravel. This article will really educate the public on the different types of falt roofing systems. I really like how you list the pros and cons for each system too.

  8. This is some really good information about flat roof. I liked that you pointed out that flat roofs are a really cheap option. That is a good thing to be aware of if you want to get a new roof.

  9. A really good friend of mine lives in a really unique apartment complex with a flat and accessible roof, and she and I are wanting to learn more about how a flat roof works and what some of its benefits are. Before reading this, I had no idea that a roof like this is really resistant to scratches. It seems to me like these roofs can be really durable and really fun! I’ll be sure to share what I’ve learned with my friend. Thanks!

  10. Very good point you made here and in the very short article it covers all the point of the perticular product.These things are very rare and very informative blog if someone is looking for roop replacement they should read this blog so they can clear I their mind and make the correct choice of the roof.

    must read Guys!

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