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Posted On: March 26, 2024

4 Common Flat Roof Materials (For Apartments, Condos, & More)

Flat roofs are a popular choice for both residential and commercial buildings due to their modern aesthetic and practicality. However, choosing the right flat roof material is crucial for ensuring durability, longevity, and cost-effectiveness. In this expert guide, we’ll delve into:

  • Various flat roof materials
  • Their characteristics
  • Pros and cons
  • Installation costs
  • Signs of damage
  • Maintenance tips

What is a Flat Roof?

A flat roof, as the name suggests, has a very low slope or no slope at all, allowing for a horizontal or nearly horizontal surface. Unlike pitched roofs, which have a steep angle, flat roofs offer unique design opportunities and can accommodate rooftop gardens, solar panels, or HVAC systems.

4 Different Flat Roof Materials

BUR roofing

Struggling to decide which flat roof materials are right for your property? Here are some of the most popular styles!

1) Built-Up Roofing (BUR):

Built-up roofing, also known as tar and gravel roofing, consists of multiple layers of bitumen alternated with layers of reinforcing fabric and topped with a layer of gravel or other aggregate. Here are its pros and cons:

✅ Pros:

  • Excellent waterproofing properties.
  • Long lifespan, typically 20-30 years.
  • Resistant to UV rays and weathering.
  • Provides good insulation.

❌ Cons:

  • Heavy, requiring adequate structural support.
  • Installation is labor-intensive and may emit odors during application.
  • Susceptible to cracking and blistering.
  • Requires periodic maintenance to replenish gravel and seal cracks.

2) Modified Bitumen:

Modified bitumen is a variation of BUR, incorporating polymer-modified bitumen membranes. These membranes are typically applied in multiple layers using heat or adhesives.

✅ Pros:

  • Flexible and durable, adapting well to temperature fluctuations.
  • Resistant to UV radiation and weathering.
  • Easy to repair with heat welding or patching.
  • Available in various colors and surface textures.

❌ Cons:

  • Installation requires specialized equipment and skilled labor.
  • Vulnerable to punctures from sharp objects.
  • Limited lifespan compared to other materials, typically 10-20 years.
  • Can be affected by poor installation practices, leading to leaks.

3) EPDM (Ethylene Propylene Diene Monomer):

EPDM is a synthetic rubber roofing membrane commonly used for flat roofs. It is manufactured in large sheets and adhered to the roof surface using adhesives, tape, or mechanical fasteners.

✅ Pros:

  • Lightweight and easy to install, reducing labor costs.
  • Highly resistant to UV rays, ozone, and weathering.
  • Flexible, allowing for expansion and contraction without cracking.
  • Low maintenance requirements.

❌ Cons:

  • Vulnerable to punctures from sharp objects.
  • Limited aesthetic options, typically available in black.
  • Prone to shrinkage over time, especially in hot climates.
  • May require periodic recoating to maintain waterproofing properties.

4) PVC (Polyvinyl Chloride):

PVC roofing membranes are made of thermoplastic material reinforced with polyester or fiberglass. They are heat-welded at seams to create a seamless, watertight barrier.

✅ Pros:

  • Excellent durability and resistance to chemicals, grease, and punctures.
  • Reflective surface reduces heat absorption, improving energy efficiency.
  • Low maintenance and easy to clean.
  • Long lifespan, often exceeding 30 years.

❌ Cons:

  • Higher initial cost compared to other materials.
  • Susceptible to punctures from sharp objects if not properly installed.
  • Not environmentally friendly, as PVC production involves toxic chemicals.
  • Limited color options and prone to discoloration over time.

Cost to Install a Flat Roof

adhering roofing

The cost of installing a flat roof depends on various factors, including the chosen material, roof size, complexity of the installation, and location. Here’s a general cost comparison:

  • Built-Up Roofing (BUR): $5-$10 per square foot.
  • Modified Bitumen: $3-$7 per square foot.
  • EPDM: $3-$8 per square foot.
  • PVC: $6-$12 per square foot.

It’s important to obtain quotes from multiple contractors and consider the long-term value and durability of each material before making a decision.

Signs of Flat Roof Damage

Regular inspection is essential for detecting potential issues before they escalate into costly repairs. Here are common signs of flat roof damage:

  • Ponding Water: Standing water on the roof indicates poor drainage, which can lead to leaks and structural damage.
  • Blisters or Bubbles: Raised areas on the roof surface may indicate trapped moisture, which can compromise the integrity of the roofing membrane.
  • Cracks or Splits: Damage to the roofing material can allow water infiltration and should be repaired promptly.
  • Membrane Tears: Tears or punctures in the membrane can compromise waterproofing and require patching or replacement.
  • Leaks or Water Stains: Interior water stains or mold growth are clear indicators of roof leaks and should be investigated immediately.

How to Maintain Your Flat Roof

Proper maintenance is key to prolonging the lifespan of your flat roof and minimizing repair costs. Here are some essential maintenance tips:

Regular Inspections

Conduct visual inspections of your roof at least twice a year, as well as after severe weather events.

Clear Debris

Remove leaves, branches, and other debris from the roof surface and gutters to prevent water pooling and clogging.

Trim Overhanging Branches

Trim trees near your roof to prevent branches from damaging the roofing membrane or blocking drainage.

Repair Damage Promptly

Address any signs of damage promptly to prevent water infiltration and structural issues.

Clean Gutters and Drains

Keep gutters and downspouts clear of debris to ensure proper drainage and prevent water backup.

Schedule Professional Inspections

Hire a qualified roofing contractor for annual inspections and maintenance to identify potential issues early.

Learn More About Flat Roofing Materials

Choosing the right flat roof material is essential for ensuring durability, longevity, and cost-effectiveness. Whether you opt for traditional built-up roofing, modern membranes like EPDM or PVC, or modified bitumen, each material has its own set of advantages and considerations. By understanding the characteristics, pros and cons, installation costs, signs of damage, and maintenance requirements of flat roof materials, you can make an informed decision that meets your building’s needs and budget. Regular inspection and maintenance are key to preserving the integrity of your flat roof and minimizing the risk of costly repairs in the long run.

Contact Northface Construction today to learn more about the best flat roof systems for your property.


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