Flat roof replacement

Flat Roof Replacement (Tips, Tricks & Pricing)

While flat roofs may seem untraditional, they’re prominent in arid regions where the drier weather means that you don’t have to worry as much about stagnating water causing roof damage. If your roof is getting older or you notice signs of a leak, it might be time to consider a flat roof replacement. Let’s look at your options and their costs.

Related: 7 Signs You Need Roof Repairs or Replacement

The 5 Best Materials for Flat Roof Replacements

When it’s time to replace your roof, the first thing you’ll need to do is determine which material you want to use for the project. Let’s look at the best and most common flat roof replacement options:

PVC Roofing

Here’s what makes PVC roofing one of the best options for flat roof replacement:

  • Longevity—PVC roofs are durable and have a minimum breaking strength of about 350 pounds per inch, which is much higher than the ASTM standard of 200.
  • Resistant to the elements—PVC roofing has excellent wind uplift resistance and a strong fire-resistance rating.
  • Waterproof—PVC doesn’t leak easily. PVC roofing membranes are almost 100% impermeable to water.
  • Energy-efficient—PVC roofing membranes reflect the intense sunlight throughout each day, saving most homeowners money on cooling costs.
  • Color options—While white is the go-to in hot climates, you can get a PVC flat roof in just about any shade imaginable.

Now, let’s look at some of the cons of PVC roofing:

  • Toxicity—Toxic chemicals get released during the manufacturing of PVC, but this isn’t something you should be too worried about when choosing a flat roof replacement material.
  • Complexity—Restoring old roofs with PVC is labor-intensive. Any leftover debris can puncture through the new PVC, causing leaks in the future.

The average installed cost per square foot of PVC roofing: $6-12

Built-Up Roofing

Here’s why built-up roofing (BUR) is an excellent material for flat roof replacements:

  • Safety—The foot traction of BUR is far superior to other roofing material options, and it is also quite resistant to fire.
  • Longevity—BURs are made out of layers, and the more layers you have, the longer the roof’s lifespan. Each layer extends its life by approximately five years.
  • Strong seal—Built-up roofing gets finished with a strong seal that you can trust to keep your roof safe.
  • Strength—Because BURs use a thick layer of gravel and stone, fallen tree branches and other debris won’t be an issue for your roof membrane.

Next, here are some cons of built-up roofing:

  • Weight—BURs are heavy, and the underlying structure must be able to support it.
  • Installation time—It takes a long time to install each layer, adding significantly to labor costs.
  • Leak repair—If you end up with a leak, finding the source is more difficult compared to other flat roof replacement materials.

The average installed cost per square foot of PVC roofing: $3-6

TPO Roofing

Benefits of TPO roofing include:

  • Cost—TPO roofing comes with many of the benefits of PVC, but at a lower cost.
  • Energy savings—Similar to PVC, TPO roof coatings reflect heat to help keep the surface temperature lower than other flat roof replacement options.
  • Maintenance—Because the surface is laminated, it’s hard for fungi and algae to stick.
  • Weight—It’s a lightweight material, weighing about a 1/2lb per square foot.

Cons of TPO roofing include:

  • It’s new—Because it’s a newer flat roof material, it’s hard to know how each manufacturer’s product will hold up over time.
  • Maintenance—Other than being slippery in the elements, making repairs to a TPO roof typically requires professional expertise and tools.
  • Fire & heat resistance—Extreme temperatures can cause cracks and leaks in TPO roofs, and it’s not as fire-resistant as PVC.

Average installed cost per square foot of TPO roofing: $10-16

Buildings with flat roofs

EPDM / Rubber Roofing 

Rubber roofing is a durable synthetic material. Its advantages include:

  • Longevity—A quality rubber roof will last for longer than other materials (up to 50 years!).
  • Easy to install—Rubber roofs come in single-layer rolls that are easy to work with and install, and the membrane flexes easily.
  • Resistance to the elements—Because of its elasticity, rubber naturally expands and contracts in the summer and winter, allowing it to withstand rough elements without wear.
  • Affordability—Rubber roofs are one of the most cost-effective flat roof replacement options.
  • Easy to repair—Finding and repairing leaks are relatively straightforward compared to some other options, like BUR.

The downsides of rubber roofing are:

  • Shrinkage—The seams of rubber roofs can break apart during installation, and the rolls are prone to shrinking away from each other. If installed improperly, leaks can begin quickly.
  • Heat—Most rubber roofs are black, which absorbs heat in the summer.
  • Aesthetics—While affordable and durable, many people shy away from rubber roofs because they don’t look as nice as PVC and TPO roofing.

The average installed cost per square foot of rubber roofing: $10-14

Modified Bitumen Roofing

Modified bitumen roofing has been around since the late 1960s, and here’s why we still use it today:

  • Aesthetics—You can get modified bitumen roofing installed in more color variations than you could ever want.
  • Easy to install—Modified bitumen commonly comes in self-adhesive rolls, making it easier and safer to install than many other options.
  • Strong seal—These flat roofs are almost 100% leak-proof and waterproof, thanks to their superior sealing abilities.

However, cons of modified bitumen roofing include:

  • Fragility—The material is more fragile than others, making it less resistant to hail, falling branches, and other debris.
  • Longevity—Modified bitumen roofs don’t hold up as long as other materials, especially in areas with lots of seasonal rainfall. Typically, they only last about 10-20 years.

The average installed cost per square foot of rubber roofing: $4-6

How Much Do Flat Roof Replacements Cost?

Laying the foundation for a new flat roof

Depending on the flat roof replacement material you choose, you can expect to pay anywhere from $5-12 per square foot. On average, $5-9 per square foot for both labor and materials is a good place to start. For residential homes, the average flat roof replacement cost is just over $6,000. For commercial buildings, you can expect the total costs to be anywhere from $40,000 to $90,000, depending on the building’s size and your chosen material.

Is it time for a flat roof replacement? Get in touch with our roofing experts today!

Related: Roof Consulting, Repair, and Replacement FAQs

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