flat roof materials

How to Choose Flat Roof Materials for Commercial Use

Choosing the right flat roof materials for your commercial building is not just a matter of practicality; it’s a critical decision that impacts the durability, energy efficiency, and maintenance costs of your roof. Imagine facing leakage issues or high cooling costs due to a poor choice of material—it’s a nightmare you can avoid with a bit of foresight and proper guidance. This post aims to be your comprehensive guide, helping you navigate the complexities involved in selecting the best material for your commercial flat roof.

Understanding Flat Roofs

Definition and Characteristics

A flat roof is designed with a slight pitch, usually less than 10 degrees, to allow water drainage. Unlike pitched roofs, flat roofs offer a sleek, modern look and additional usable space.

Common Uses in Commercial Settings

Flat roofs are a popular choice for various commercial buildings, such as warehouses, retail stores, and office complexes. Their advantages often align well with the functional requirements of these structures, offering both aesthetic appeal and practical benefits.

Benefits of Flat Roofs

  • Usable Space: Ideal for HVAC systems, solar panels, and roof gardens.
  • Ease of Maintenance: Safer and easier to inspect and maintain compared to pitched roofs.
  • Cost-Effectiveness: Often less expensive in terms of materials and installation costs.

Key Factors to Consider

When choosing the best material for your commercial flat roof, several critical factors should guide your decision:

Climate and Weather Conditions

Different flat roof materials perform better under various climatic conditions. For example, a membrane roof may offer excellent performance in regions with heavy rainfall, while a flat roof design with built-up roofing (BUR) can withstand harsh winters and extreme temperatures.

Durability and Longevity

Understanding the lifespan and durability of your chosen material is crucial. Opt for materials known to resist environmental damage, wear, and tear.

Energy Efficiency

Roof materials play a significant role in regulating indoor temperature. Reflective surfaces and good insulation properties can significantly impact your building’s heating and cooling costs.

Maintenance Requirements

Some materials require frequent inspections and maintenance, while others are relatively low-maintenance. Consider long-term maintenance costs when making your decision.

Budget Constraints

Balancing quality and affordability is essential. While some materials have a higher initial cost, they can offer long-term savings through durability and reduced maintenance needs.

Local Building Codes and Regulations

Always check local building codes to ensure your chosen material complies with legal requirements. Consulting with a building inspector or expert can also help avoid costly mistakes.

Overview of Popular Flat Roof Materials

Below, we delve into some of the most popular flat roof materials, discussing their pros and cons to help you make an informed decision.

Built-Up Roofing (BUR)

Composition: Several layers of asphalt or tar alternated with layers of felt or fiberglass.


  • Multiple layers provide durability.
  • Excellent UV and weather resistance.


  • Heavier than other materials.
  • Labor-intensive to install.

Modified Bitumen

Types: APP (Atactic Polypropylene) and SBS (Styrene Butadiene Styrene).


  • Offers good tensile strength.
  • Easier to install compared to BUR.


  • Susceptible to UV damage without a protective coating.

Thermoplastic Olefin (TPO)

Characteristics: Single-ply reflective membrane made from ethylene-propylene rubber.


  • Cost-effective.
  • Reflective surface aids in energy efficiency.


  • Vulnerable to punctures and tears.

Ethylene Propylene Diene Monomer (EPDM)

Material Properties: Rubber roof material often referred to as “rubber roofing.”


  • Long lifespan.
  • Excellent UV and weather resistance.


  • Black surface can absorb heat unless treated.

Polyvinyl Chloride (PVC)

Composition: Single-ply roofing membrane that offers a durable, long-lasting solution.


  • Strong and resistant to chemicals and fire.
  • Energy-efficient reflective surface.


  • Higher initial cost.
  • Potential environmental concerns.

Spray Polyurethane Foam (SPF)

Application Process: Applied as a liquid that expands into a foam, creating a seamless layer.


  • Seamless and self-flashing.
  • Excellent insulation properties.


  • Requires specialized installation.
  • Regular inspections are necessary.

Comparative Analysis

To make a sound decision, it’s crucial to compare these materials based on a range of performance metrics, costs, and suitability.

Performance Metrics

Material Durability Energy Efficiency Maintenance
BUR High Moderate High
Modified Bitumen High Moderate Moderate
TPO Moderate High Moderate
EPDM High Low (untreated) Low
PVC High High Moderate
SPF High High High

Cost Analysis

Material Initial Cost Lifespan Long-term ROI
BUR Moderate 20-30 years High
Modified Bitumen Moderate 20-30 years High
TTO Low 15-20 years Moderate
EPDM Moderate 25-30 years High
PVC High 20-30 years High
SPF High 20-25 years High

Suitability to Various Commercial Applications

Choosing the right material depends on the specific requirements of your building:

  • Warehouses: Modified Bitumen or TPO for better energy efficiency and strength.
  • Retail Stores: BUR or PVC for durability and appearance.
  • Office Buildings: EPDM for longevity and low maintenance.

Expert Tips for Making the Final Choice

Consult with Roofing Professionals

Roof construction is complex, and a professional can provide invaluable insights to ensure you choose the best flat roof material for your building.

Consider Future Expansion and Renovation Plans

Choose flexible materials that can adapt to future changes without compromising integrity.

Evaluate Warranty and Insurance Options

Select materials with robust warranties and check how they impact your insurance premiums. Ensuring your flat roof installation is insurance-friendly can save unexpected costs later.


Choosing the right flat roof materials involves thorough evaluation of your specific needs, climate, budget, and long-term plans. From built-up roofing to rubber roof material like EPDM, each option offers distinct advantages and potential drawbacks. By weighing these factors carefully, you can make an informed decision that ensures durability, cost-effectiveness, and energy efficiency.

Call to Action

What challenges have you faced in choosing flat roof materials for your commercial buildings? Share your experiences and questions in the comments below! For more expert tips and advice on roof construction and flat roof replacement, subscribe to our blog.

Additional Resources

Links to Further Reading

Contact Information for Professional Consultations

Have more questions? Reach out to our team of experts for personalized consultations on your flat roof construction and installation needs. 

  • Email: info@jrswigart.com
  • Phone: (509) 547-4851

By integrating this depth of information and practical advice, this blog post aims to be the ultimate resource for any commercial property owner or manager facing the important decision of selecting flat roof materials.


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