Flat Roofs in Arizona

If you’re new to Arizona, you may have noticed not every home has a traditional pitched roof. Don’t be alarmed! Unlike other places in the country, we don’t have heavy snow piling up on our roofs, so flat roofs are common. There are four main types of flat roofs: Built-up, modified bitumen, spray polyurethane foam, and rubber membrane roof. Read on for some basic information our clients have found useful regarding flat roofs in Arizona.

Built-Up Roof (BUR)

A built-up roof is a more traditional hot tar and gravel roof. It's constructed with layers of waterproof material and hot tar. This type of roof has come a long way from its inception and now are frequently created with fiberglass membranes instead of tar paper.

Modified Bitumen Roof

This variety of flat roof is considered a "cousin" of the built-up roof. It consists of asphalt rolls around 3 feet wide of five layers, including insulation, modified base sheets or plies, modified bitumen membranes, adhesive, and surfacing. Some modified bitumen and BUR roofs can have acrylic or silicone coatings applied to extend the life of the roof.

Spray Polyurethane Foam (SPF) Roofs

As the name implies, the roof begins with a layer of polyurethane foam, which is then coated with some type of waterproofing elastomeric topcoat. The topcoat is typically UV reflective, which can help keep heat out during the summer. Every 1” of SPF has approximately an r-6.5 insulation value, which indicates how much the material can resist heat flow. Typical homes will have 1” of foam applied.

Rubber Membrane Roof

Rubber membrane roofs are typically made from synthetic rubber, thermoplastic, or modified bitumen. Thermoplastic polyolefin (TPO) is one of the best types of rubber roofs in Arizona due to its heat-reflective and energy-efficient nature. While more common on commercial roofs, TPO roofs are growing in popularity in the residential sector as well.

Each 1” of poly-iso foam has approximately r-6.8 but can diminish with age.  Typical homes will have 1-1.5” of poly-iso foam, while some commercial buildings may have up to 6” of poly-iso foam.

Pros to Flat Roofs

Flat roofs offer many advantages to both homeowners and business owners alike. Some of the biggest pros are the cost of flat roofs and the easier maintenance and installation.

Maintenance

Flat roofs are easier to maintain than their pitched counterparts. It's a simpler process to check sidings or fill in holes on a flat roof where you're not worried about falling off a pitched roof. Properly maintained SPF roofs can last 30+ years!

Quicker Installations

Due to the streamlined nature of a flat roofing system, installing a new roof is a quicker process than on a pitched roof. You won't have as much downtime waiting for your new roof to be installed. Most flat roof jobs can be completed within a day, so there's no need to clear a large portion of your schedule just for roofing work. 

Expand Your Outdoor Space

Many homeowners and businesses alike turn their flat roof into extra useable space, depending on how easy it is to access. If you're a homeowner, you can think of turning this area into an additional patio or rooftop garden. For businesses, flat roofs can be a great place to hide extra equipment if structural integrity permits.

Cons to Flat Roofs

Although flat roofs come with many advantages, there are also some cons to be aware of when considering this type of roof.

Limited Insulation

Since there's no attic beneath a flat roof, there's not very much room for insulation. Because of this, flat roofs can be more susceptive to major swings in the outside temperature. If you choose a foam roof, however, you can select a UV coating that will help reflect some of the heat and control the temperature during our hot Arizona summers.

Aesthetics

While flat roofs can fit in relatively well with our southwestern architecture, not everyone finds them aesthetically pleasing. This can be a significant detractor for someone weighing the pros and cons between a flat roof and a pitched roof, especially if a flat roof doesn't fit in as well in their neighborhood.

Replacements

Although flat roofs are easier to replace and maintain, their lifespan isn't as long as a pitched roof. A typical flat roof lifespan is between 10-15 years before they must be replaced, or 5-7 years before they must be recoated. A pitched roof can get between 25-50 depending on the roofing materials and maintenance.

At the end of the day, whichever type of roof you go with, make sure you keep up with its maintenance. We recommend you do a roof inspection every 2 years and do any of the work quoted by a roofing professional to maximize the life of your roof and your overall investment.

We hope you found this helpful. If you still have questions, send us a message, or give us a call (520) 300-2597.

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