5 Common Flat Roof Types (Pros & Cons)

A flat roof are a popular choice for commercial and residential buildings alike, offering a modern aesthetic and practical benefits such as additional usable space for gardens, patios, and HVAC systems. For property developers, understanding the various types of flat roofing materials is crucial to making an informed decision that balances:

• Cost
• Durability
• Functionality

In this guide, we’ll explore five prominent types of flat roofs: Built-Up Roofing (BUR), Modified Bitumen, EPDM Roofing, TPO, and PVC.

1. Built-Up Roofing (BUR)

Built-Up Roofing, commonly referred to as BUR, is one of the oldest and most reliable methods for flat roofs. It consists of alternating layers of bitumen (asphalt or tar) and reinforcing fabrics. The top layer is often finished with gravel or a reflective coating to protect against UV radiation and improve fire resistance.

Benefits of BUR

• Durability: BUR systems are known for their long lifespan, often lasting between 20 to 30 years if maintained properly.
• Waterproofing: The multiple layers provide excellent waterproofing, reducing the risk of leaks.
• Fire Resistance: The top layer of gravel or reflective coating enhances the fire-resistance properties of the roof.
• Cost-Effective: While initial installation can be labor-intensive, the long lifespan often makes it a cost-effective option in the long run.

Drawbacks of BUR

• Weight: The multiple layers make BUR relatively heavy, requiring a strong structural foundation.
• Installation Time: The installation process can be lengthy and requires skilled labor.
• Odor: The use of hot tar or asphalt can produce unpleasant odors during installation.

Ideal Applications

BUR is ideal for larger commercial buildings where the structure can support the weight and where long-term durability is a priority.

2. Modified Bitumen

Modified Bitumen roofing evolved from the BUR system and incorporates polymer-modified bitumen with reinforcing fabrics. This creates a single-ply roofing membrane that offers enhanced performance characteristics.

Benefits of Modified Bitumen

• Flexibility: The addition of polymers provides greater flexibility, even in colder temperatures.
• Ease of Installation: Available in rolls, it can be installed using a variety of methods, including torch-applied, cold-applied, and self-adhered systems.
• Durability: Offers good resistance to physical damage and weathering.
• Maintenance: Easier to maintain and repair compared to BUR systems.

Drawbacks of Modified Bitumen

• Cost: Generally more expensive than traditional BUR systems.
• UV Sensitivity: Can degrade over time without proper UV protection.

Ideal Applications

Modified Bitumen is suitable for both residential and commercial buildings and is particularly beneficial in areas with extreme temperature variations.

3. EPDM Roofing

EPDM (Ethylene Propylene Diene Monomer) is a type of synthetic rubber roofing membrane that is widely used in low-slope buildings. It is known for its durability and versatility.

Benefits of EPDM

• Durability: EPDM roofs can last up to 50 years with proper maintenance.
• Weather Resistance: Excellent resistance to UV radiation, ozone, and extreme weather conditions.
• Flexibility: Remains flexible in cold temperatures, reducing the risk of cracking.
• Ease of Installation: Available in large sheets, reducing the number of seams and potential leak points.

Drawbacks of EPDM

• Aesthetics: Typically available in black, which can absorb heat and increase cooling costs.
• Chemical Sensitivity: Can be damaged by certain chemicals and solvents.
• Seam Vulnerability: While the number of seams is minimized, they can still be a weak point if not properly sealed.

Ideal Applications

EPDM is ideal for commercial and residential buildings that require a durable, long-lasting roofing solution, particularly in regions with harsh weather conditions.

4. TPO (Thermoplastic Olefin)

TPO is a single-ply roofing membrane made from a blend of polypropylene and ethylene-propylene rubber. It combines the durability of rubber with the performance advantages of hot-air weldable seams.

Benefits of TPO

• Energy Efficiency: Reflective surface helps reduce cooling costs by reflecting UV radiation.
• Durability: Good resistance to punctures, tears, and chemical exposure.
• Ease of Installation: Can be installed using various methods, including mechanically attached, fully adhered, or ballasted systems.
• Seam Strength: Hot-air welded seams provide strong, reliable joins.

Drawbacks of TPO

• Longevity: While generally durable, the lifespan can vary based on the quality of the material and installation.
• Installation Expertise: Requires skilled labor for proper installation to ensure seam integrity.
• Chemical Compatibility: Limited resistance to certain chemicals compared to EPDM.

Ideal Applications

TPO is an excellent choice for commercial buildings focused on energy efficiency and cost-effective installation.

5. PVC (Polyvinyl Chloride)

PVC is a type of plastic roofing membrane known for its strength and durability. It is commonly used in both commercial and residential applications due to its excellent performance characteristics.

Benefits of PVC

• Durability: Can last over 20 years with proper maintenance and is highly resistant to punctures and tears.
• Chemical Resistance: Excellent resistance to chemicals, grease, and industrial pollutants.
• Energy Efficiency: Reflective surface helps reduce energy costs by reflecting sunlight.
• Fire Resistance: Naturally fire-resistant, reducing the risk of fire spread.

Drawbacks of PVC

• Cost: One of the more expensive flat roofing options.
• Flexibility: Less flexible than EPDM, making it more prone to cracking in extremely cold temperatures.
• Environmental Impact: Made from plastic, raising concerns about environmental sustainability.

Ideal Applications

PVC is best suited for commercial and industrial buildings where chemical resistance and durability are critical, and the budget allows for a higher initial investment.

Let Us Design A Flat Roof System for You

Selecting the right flat roofing material for your property development project requires a thorough understanding of each option’s benefits and drawbacks. Whether you prioritize cost, durability, energy efficiency, or ease of installation, there is a flat roofing solution to meet your needs.Ready to choose the perfect flat roof for your next project? Contact our experts today for personalized advice and a free consultation. Let’s build something great together!