What's the Best Roof Covering for a Flat Roof in Arizona?

Several homes in Arizona sport a flat roof (also called a low slope roof) because there’s less surface area to absorb heat, helping your home stay cool.

But what’s the best roof covering for your flat roof?

You have several choices. But we bet you’re busy. So we’ve narrowed it down to your 2 best choices:

We’ll explain the pros and cons of these roof coverings.


Over 90% of Arizona roofs use spray polyurethane foam to cover over an existing flat roof.


  • Energy-efficient—Foam insulates your home, lowering your energy bills as a result.
  • Waterproof—There are no seams, so water can’t leak through.
  • Long lifespan— It’s resistant against ultraviolet rays, so it can help your roof last for 30+ years.
  • Easy to maintain—The roof does not need yearly maintenance. But it does need re-coating every 5 to 10 years since the protective covering wears thin.
  • Quick and easy to install— It’s lightweight, meaning the roofer can install it over your old roof (in most cases). Since they don’t have to remove your current roof, installation is much faster.


  • Expert foam roofer needed— The foam is formed by mixing 2 liquid compounds. You’ll need someone who has the right equipment and knows how to mix and apply the foam to get the job done right.
  • Expensive upfront cost—This is the most expensive Arizona flat roof covering. While the upfront cost is high, you’ll save more in the long run due to energy efficiency savings, low maintenance cost, and long lifespan.

Modified bitumen (asphalt)

Modified bitumen (asphalt) is a single ply (layer) membrane that is rolled over the flat roof’s surface.

It has a rubber backing with asphalt granules on top. The installer uses a torch to melt the rubber onto the flat roof’s fiberglass base, allowing the tough granule side to be face up.


  • Lower upfront cost—Negligibly less expensive than foam roofing’s upfront cost
  • Consistent product quality—Modified bitumen roofing goes under strict quality control standards, making sure there’s uniform thickness and consistent physical properties throughout the membrane
  • Can be easy to install— Some manufacturers have made a self-adhered base sheet so you can just stick the modified roofing on top without needing a torch.


  • Installation may cost extra and take longer— If the roofer has to tear off an old roof, you’ll have to pay extra. This also takes more time.
  • Possible fire hazard—It’s not recommended to use a torch when applying the modified roof to an occupied home.
  • Not scuff resistant—Roof covering can scuff and tear.


Like most things in life, you get what you pay for. Foam is the most expensive for a reason: it lasts a long time and saves you more money in the long run.

But if you have a limited budget, then modified bitumen is a good choice.

Need a roofing estimate for your flat roof? Contact Lyons Roofing for a FREE estimate! We serve the Phoenix and Tucson areas.