Built-Up Roofs: Buyer’s Guide

Get the complete lowdown on built-up roofs. From fabrication to benefits, costs, and comparisons, our guide helps you choose the right roofing option.
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Reviewed by JC Sanjuan — General and roofing contractor with over a decade of experience in residential and commercial construction. He specializes in project management, quality workmanship, client satisfaction, and solving roofing challenges.

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If you’re in the market for a new roof, especially a flat one, consider built-up roofs as an option. Picking a roof isn’t just about looks; it’s a big choice that affects how long your home lasts and how much it’s worth. And when it comes to flat roofs, built-up roofing is a tried-and-true method that’s been around for decades.

So why should you even think about built-up roofs? Well, they offer a mix of affordability, durability, and versatility that’s hard to beat. In this guide, we will dig into what built-up roofs are, how they’re made, their benefits, and even how they stack up against other roofing types. Stick around, and you’ll become a bit of a roofing expert yourself!

What Are Built-Up Roofs? 

So, what’s the deal with built-up roofs? In simple terms, a built-up roof consists of alternating layers of asphalt or bitumen and reinforcing fabrics. This “sandwich” of layers is then topped off with a layer of gravel or a special coating to protect against weather and UV rays. The end result? A robust, sealed surface that keeps the elements out.

This type of roofing has been around for a long time and is especially popular for commercial buildings and multi-family residential complexes. It’s a go-to choice when durability and longevity are high on your priority list.

How Are They Made? 

You might wonder, “How do they put these layers together?”

What is a Built-Up Roof and why should I use it?
Source: Karnak

Great question! The construction of a built-up roof starts with a solid, clean base—usually a roof deck made of metal, concrete, or sturdy wood. Next comes the vapor barrier to keep moisture at bay. After that, the fun begins.

Multiple layers of bitumen and fabric are applied, each one heat-sealed to the one below it. It’s a layering game, almost like making lasagna. The topmost layer is usually a protective surfacing material like gravel or a weather-resistant coating. This “cake” of layers creates a strong barrier against water, wind, and even fire to some extent. Yep, built-up roofs are designed to be tough!

Benefits of Built-Up Roofs 

Alright, so why should you even consider a built-up roof? First off, these roofs are like tanks—they can take a beating. The multiple layers make them incredibly durable, withstanding both heavy foot traffic and extreme weather conditions. Got a hot summer or a freezing winter? No problem. Built-up roofs are also energy-efficient, helping to keep your indoor temperature stable, and that means lower utility bills for you.

Additionally, built-up roofs offer fantastic water resistance. Those multiple layers serve as an excellent barrier against leaks, even in the worst downpours. And let’s not forget about fire resistance; the gravel or coating on top can serve as a fire retardant. So, all in all, you get a roof that’s strong, durable, and built to last. 

Comparison to Other Flat Roof Options 

So, how do built-up roofs measure up against other flat roofing choices? You might be considering options like TPO, EPDM, or modified bitumen. Each has its perks, but built-up roofs have a blend of benefits that make them a strong contender. 

Let’s take a quick look:

  • Single-Ply Membrane: These are lighter and easier to install but may not offer the same level of durability as a built-up roof.
  • Modified Bitumen: Similar in many ways to built-up roofs but generally comes in at a lower cost. However, they’re not as robust in terms of longevity.
  • Rubber Roofs (EPDM): Known for being extremely weather-resistant, but they can be punctured more easily than built-up roofs.
  • Metal Roofs: Highly durable but can be more expensive and are often not as insulating.

Unlike TPO and EPDM, which are single-layer systems, the multiple layers in a built-up roof offer extra durability and leak resistance. Compared to modified bitumen, built-up roofs generally have a longer lifespan and can be more cost-effective in the long run.

But it’s not all sunshine and roses. Built-up roofs take longer to install and can be heavier, requiring a stronger roof deck. So, while they pack in many benefits, make sure your building can handle the weight and that you’ve got the time for a more extended installation.

Pros and Cons 

By now, you’ve probably got a good sense of what built-up roofs bring to the table. But let’s be honest; every rose has its thorns. Here are the pros and cons to help you make an informed decision.

Pros:

  • Durability: We’ve said it before, but it bears repeating—these roofs are built to last.
  • Leak Resistance: Multiple layers mean fewer opportunities for water to find its way in.
  • Energy Efficiency: The thick construction provides excellent insulation.
  • Fire Resistance: The gravel or special coating can act as a fire retardant.

Cons:

  • Weight: These roofs are heavy, so make sure your building can handle the load.
  • Installation Time: All those layers take time to install, so plan accordingly.
  • Cost: Initial setup can be pricier than single-layer options, but remember, you’re investing in durability.

So there you have it. Built-up roofs offer a ton of benefits but come with a few caveats. Weigh these pros and cons carefully to decide if a built-up roof is the right fit for you.

Built-Up Roofs – Installation Process 

So you’re sold on a built-up roof, but what’s the installation process like? First, the existing roof might need to be torn off or prepared—no shortcuts here. Then, the roof deck is inspected to make sure it can hold the weight. 

Next, the vapor barrier is laid down, followed by the alternating layers of bitumen and reinforcing fabric. These layers are fused with heat or adhesive, making a seamless barrier.

It’s essential to have a professional, like myself, with experience in built-up roofing handle this job. Why? Because every layer must be carefully aligned and sealed to ensure top-notch performance. Once the layers are down, a protective top layer is added. This could be gravel or a specialized coating. And just like that, your built-up roof is ready to face the elements.

Costs of Built-Up Roofs

Alright, let’s talk numbers. Built-up roofs aren’t the cheapest option out there, but you get what you pay for. On average, you can expect to pay between $4 to $6 per square foot for materials and installation in the U.S. 

It might seem steep, but remember, this is a long-term investment.

If you’re based in or near Orlando, FL, where I work, the costs align with the national average. However, factors like the complexity of your roof, the type of top layer you choose, and labor rates can all impact the final price.

Considering the durability and other benefits, many people find the cost of a built-up roof to be well worth it. Just remember that the upfront cost is higher, but the roof’s longevity often makes it cost-effective in the long run.

Conclusion

Ultimately, your choice will depend on various factors, including budget, durability requirements, and aesthetic preferences. A built-up roof is a solid, reliable option, but it’s always good to weigh it against your other choices.

That wraps up our comprehensive guide on built-up roofs. Don’t hesitate to reach out if you’re in the Orlando area and looking for a roofing expert.


Frequently Asked Questions 

You might still have a few questions swirling around in your mind. No worries, let’s address some of the most commonly asked questions about built-up roofs.

  1. How long does a built-up roof last?
    Typically, a well-installed and maintained built-up roof can last anywhere from 15 to 30 years.
  2. Can I install a built-up roof myself?
    While it might be tempting to tackle this as a DIY project, the multiple layers and specialized materials call for professional installation.
  3. How do I maintain a built-up roof?
    Regular inspections and cleaning are essential. Remove debris and check for signs of wear or damage at least twice a year.
  4. Are there eco-friendly options?
    Yes, many built-up roofs now come with energy-efficient top coatings that can help you save on energy bills.
  5. What if my building can’t handle the weight?
    In that case, consult with a roofing professional about alternative options that could be a better fit for your building.

References

  1. National Roofing Contractors Association. The NRCA Roofing Manual: Membrane Roof Systems. NRCA, 2023. https://www.nrca.net/
  2. “Built-Up Roofing Systems: Advantages and Disadvantages,” Roofing Contractor Magazine.
    https://www.roofingcontractor.com
  3. “Built-Up Roofing,” National Roofing Contractors Association.
    https://www.nrca.net
  4. “How to Maintain a Built-Up Roof,” Facility Management Journal.
    https://www.fmj.com
  5. “Built-up Roofing Costs,” HomeAdvisor.
    https://www.homeadvisor.com
  6. “A Comparative Study of Commercial Roofing Systems,” Journal of Architectural Engineering.
    https://ascelibrary.org
  7. “Understanding Different Types of Flat Roof Material Options,” The Balance Small Business.
    https://www.thebalancesmb.com
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