Costs to Install Flat Roofs

Types of Single Ply Flat Roofs and Their Costs

Not all flat roofs are created equal.

Flat roofs are among the most affordable roofs over time and they can be installed on commercial buildings and residential properties alike. But there isn’t just one single type of flat roof, and choosing the right type is vital to getting a roof that fits well and does the job.

But which type of single-ply flat roof is right for you home, and how much is it going to cost to have it installed?

Types of Single-Ply Flat Roof Materials

There are 4 main types of single-ply flat roofing. They are:

Modified Bitumen




Why Use Single-Ply Roofing?


Durable. Single-ply roofing can handle all different kinds of weather and storms without fail. The sheets are usually completely impermeable to water, and if installed properly, sealed against leaks at seams and joints. They are also much less likely to crack or warp in extreme heat or cold, unlike traditional roofing materials. All in all, flat roof coatings are resistant to the elements which make flat roofs among the longest lasting roofs you can have .

Chemical Resistant. This makes single-ply roofing an excellent choice for places with exposure to acid rain.

Very reflective. Sunlight and UV rays bounce right off instead of being absorbed, keeping the building much cooler and avoiding damage from UV rays over the long-term.

Easy and quick to install. Single-ply roofing is generally installed using one of several methods, some of which use heat do adhere it to the roof, and some which do not. Ballasted (weighing the roofing down) and adhered (using heavy-duty, industrial-grade adhesive on the back of the roofing ply) are the most common these days, and the easiest. Heat methods often involve the use of blowtorches and can be a bit more complicated and time-consuming.

Average Cost of Flat Roofs

flat roof cost Arizona

Low end is $6,815 | Mid Range is $8,769 | High End is $11,211

SPF Single-ply Flat Roof Cost

Materials: $2.25 to $2.75 per square foot

Installation:$6.00 to $8.00 per square foot

SPF is a spray polyurethane foam that offers one of the most energy-efficient ways to seal a single-ply roof. This type of polyurethane is closed cell foam that’s very stiff when the components have fully cured. They are pumped through two tubes that mix the components together and the chemical reaction causes the two liquids to react. A thin foam layer is created over your rooftop that seals everything that the foam is sprayed onto.

Not only is this foam incredibly durable and resistant to heat, but it also keeps heat out from the foam density. The thermal resistance (R-value) is very good for beating the heat of AZ heat beating down. Since the density of the foam is more effective over other flat roof materials, it’s perfect for insulation that protects against water and moisture. It won’t be uncommon that the lifespan of SPF roof coating can last upwards of 50 years.

As with most spray systems that involve SPF coating, experience does count for everything. If not properly trained, technicians will harm the quality of the finished coating. It’s important to know that the work being done will ensure this work lasts as long as it promises. Because of the tricky nature that can affect the curing of polyurethane foam, this process needs to be done in the driest months of the year. Thankfully, here in Phoenix, Arizona we have plenty of dry days through the year, so finding the right time window is flexible for your roof. Of course, there must be some preparation that is done beforehand to remove dirt and material that will prevent the SPF layer from adhering correctly. This cleaning process will also facilitate the long-lasting lifespan of this coating. Allowing the polyurethane foam to seal gaps and spots where moisture and water could enter is worth the extra work.

This makes the efficiency of an SPF roof to have the highest level of durability your roof deserves. If you live here in the Valley of the Sun, we are more than happy to provide you with a free estimate to restore or renew your current deck or roof surface.

Modified Bitumen Single-ply Flat Roof Cost

Materials: $1.20 — $2.50 per square foot

Installation: $5.00 — $7.00 per square foot

Modified Bitumen is considered a specialty type of flat roofing. It is manufactured from asphalt and contains rubber modifiers, and this combination of elements means it’s a pretty environmentally-friendly choice. While it doesn’t hold up very well to foot traffic, it is easy to repair.

Modified Bitumen is installed in 4 different ways – both hot and cold. The first way is held on by hot tar, the second being applied with a solvent- based adhesive that doesn’t need any kind of heat, and the third – and most common – is rolling it onto the roof and heating it with a torch to help it stick firmly the surface below.

The newest bitumen roofing can also be installed without heat – instead using a sticky adhesive backside that is exposed by peeling back the outer layer.

Modified bitumen roofing is uncommon on homes but can be found on many commercial buildings and businesses. You can tell if your home has a modified bitumen roof by looking for seams in the roofing very three feet, or for the granulated look that the top layer has, similar to asphalt but smoother and often with a coating to repel water.

EPDM (Rubber) Single-Ply Flat Roof Cost

Materials: $1.40 per square foot

Installation: $5.00 — $7.00 per square foot

EPDM (Ethylene Propylene Diene Terpolymer) is the most commonly installed single-ply flat roof material – for both commercial and residential application – due to its ease of installation, light weight, and affordability. It’s also entirely UV resistant, so it will last virtually forever – even here in the Phoenix area. You easily get at least 20-30 years out of properly-installed and maintained EDPM rubber roofs, and some will last even longer.

Quality work and diligence is imperative for installing rubber roofs, as the seams can be tricky and tough to get right. A glue-based solvent is used to hold the seams together, and eliminating all air pockets in the seals can be difficult, leading to leaks and other problems. As a result, they often require some ongoing maintenance. Thankfully, they are still quite easy and inexpensive to repair.

Rubber roofs are quick and easy to recognize, based on the two basic ways they are installed: ballasted and adhered.

Adhered rubber roofs are the easier type of rubber roof to spot. They’re usually black are stretched tautly a fiberboard or insulation board to create a tight, sealed surface.

Ballasted rubber roofs, on the other hand, are weight down with the use of a ballast (often large stones) that sits on top of the roofing. These stones are usually not held on with tar and can be easily moved around when you need to access or repair the rubber roofing.

Because it’s dark in color – and heat does not reflect — don’t expect save on your energy bills using an EDPM rubber roof. Rubber surfaces will be hotter than any other single-ply roof.

PVC Single-ply Flat Roof

Average Cost of a PVC Roof

Materials: $1.90 per square foot

Installation: $6.00 — $8.00 per square foot

When it comes to durability, PVC is at the top of the pack. This very common household plastic is used as roofing to stand up to heat, cold, wind and rain. It’s usually applied in a single layer in white or grey. Seams with PVC are non-existent as they are hot-welded when installed, making PVC practically leak-proof (TPO also shares this same characteristic).

PVC is installed in sheets that are attached either by being adhered, mechanically attached or ballasted. It’s a great choice for commercial buildings and homes throughout Arizona, as it reflects a lot of heat and can keep the roof and the home so much cooler. And because it’s so durable, you can expect manufacture warranties to extend upwards of 25 years – some even come with lifetime warranties. Like other single-ply roofing materials, it’s great for waterproofing and isn’t degraded by sunlight.

How do you know if you have a PVC roof? Easy; is it a single white or grey color? Is it stretched tightly over the roof? Then it’s likely PVC. If not, it’s…..

TPO Single-Ply Flat Roof Cost

Materials: $1.90 per square foot

Installation: $6.00 — $8.00 per square foot

TPO is a plastic, like PVC, and looks a lot like it; white or grey and stretched in tight sheets over the surface of the roof. comprised of polypropylene and ethylene propylene polymers It’s known for its strength and can be three times stronger than EPDM roofs. In some cases, TPO sheets also include polyester for even more added durability.

This durability has been the driving factor behind its continued increase in popularly as the roofing material of choice for commercial buildings. TPO roofs are also an ideal choice for roofs here in Arizona because they do such a good job at reflecting heat. And like most other single-ply roofing materials, TPO is extremely resistant to UV rays, and will not degrade from the constant sun exposure we get here in the Southwest.

Are There Any Downsides to Single-Ply Roofing?

As with all roofing types, these materials do have some shortcomings. The plies are sometimes rather thin, and they can be easily punctured by sharp, flying objects. And because the roof is flat, they can sometimes retain a lot of water that puddles up and has nowhere to drain; proper drainage along seams is crucial to a good, durable roof.