Re-roofing at Tree Services in Elyria, Ohio

Three Re-roofing Options for Flat Roofs

Greg PalyaSpray Polyurethane Foam Roofing

So, you have a flat roof and it’s leaking. What repair options do you have?

You could:

  • Remove and install the same roofing system you already have
  • Add coating over an existing roof
  • Install spray polyurethane foam over your existing roof

picture of a finished spray foam roof


But first, we recommend getting a roofing contractor onto the roof.


Because once the current conditions of the roof are determined, then you’ll know the best repair option.

For one, maybe the roof isn’t in bad shape. Therefore, you can do a simple repair over a small area and you’re done.

Or, maybe your flat roof has a small leak, but over 50% of the insulation is wet. In this case, tearing the roof off might be in your best interest.

And if you’re somewhere in the middle, perhaps re-roofing is the most cost-effective roof repair option for you.

At West Roofing Systems, we’ve been inspecting all kinds of commercial roofs since 1979. We specialize in spray foam roofing, as well as roof restoration with coating, but we’ll always give you the most cost-effective option based upon the current conditions of your roof.

Let’s get into the three options you’ll have for re-roofing a flat roof.


Re-roofing option #1 – Install the same roofing system

City of Lorain - EPDM Installation

If you have a single-ply, metal, built-up, or any kind of commercial roofing system, you can always remove what you have and install the same system.

Maybe you’re a fan of single-ply roofing systems, so you’re going to stick with that.

Perhaps there have been improvements in single-ply’s since your last installation?

No matter which roof system you currently have, you’ll always be able to remove it and install a new one.

NOTE: In some cases, completely removing a roof system on your flat roof is NOT a cost-effective way to get your roof watertight. Read more cost-effective options below.


Re-roofing option #2 – restore your roof with an elastomeric coating

Silicone roof coating system installed over a school


Let’s say you did have that single-ply roof with a few leaks.

After an inspection, it’s determined that 15% of the roof’s insulation is saturated.

A cost-effective option that some building owners don’t know about is a roof coating restoration.

This is done by installing high-quality, waterproof silicone over an existing roof.

How is this done?

To restore a roof (let’s say it’s an EPDM rubber roof), a roofing contractor would identify where all the wet insulation is and remove only those areas.

They will replace the wet insulation with new, dry insulation and EPDM.

Now they will prepare the existing roof by power washing the roof clean. They will also perform adhesion tests to make sure the coating will adhere correctly.

Next, they will treat the seams (since these areas are prone to leaking).

Then, they will apply a certain thickness of the coating to the entire roof.

NOTE: A roof restoration saves money versus a complete replacement/tear-off because the contractor is only removing the wet areas of the roof.

Re-roofing option #3 – Install a spray foam roofing system

If your flat roof is leaking, it could be due to several things, such as:

  • There isn’t a proper slope to transport water to drains
  • There are holes in the membrane
  • Flashings around penetrations aren’t watertight

If any of these things are happening to your flat roof, an option to consider is a spray foam roof.


Because spray foam can eliminate all three of the issues above.

How so?


Spray foam can influence proper slope

With spray foam being fluid-applied, a contractor can add as much slope as needed in certain areas of the roof.

Some areas might be raised 1 inch, some only ½ of an inch.

Some areas that have ponding/standing water might be 10ft. by 10ft., other areas might be 2ft by 2ft.

Regardless, because spray foam is spray-applied, a certified installer can customize the slope of an entire roofing system so that water is always headed towards the drains.


Spray foam fills in holes in the membrane

Did you know that spray foam expands 30x its size within a few seconds?

Because spray foam creates a monolithic (one layer) roofing system, it can fill all the existing holes that a roof membrane has.


Spray foam can make flashings watertight again

Over time, flashings begin to break down, lose adhesion, or become cracked, which gives water an entry point into the insulation.

With foam being spray-applied, a contractor can spray over the top of the existing flashings and make it a part of the one-layer roofing system.



What are you supposed to do with your flat roof now?

The first step is to contact a roofing contractor. They will set up an appointment with you to walk the roof and perform a roof inspection.

Once they complete the inspection, they will give you possible solutions based on what they found on the roof.

You can then begin to weigh the pros and cons of each option and decide.

Would you like West Roofing Systems to see your roof? We service everywhere East of the Mississippi, but you can see our services areas here.

Would you like to learn more about spray foam or silicone roof coating systems?

If so, please download our guide below!


download the silicone roof coating cheat sheet


The spray foam roofing cheat sheet - download now

About the Author

Greg Palya

Greg Palya is the Digital Content Manager of West Roofing Systems, Inc. He has a B.S. in Marketing from the University of Akron and an MBA in Marketing from Walsh University. When he's not trying to teach others about spray foam roofing and silicone roof coatings, you can find him on the basketball court or golf course.