Types of Commercial Roofing: Systems, Benefits, and Selection Guide

Commercial roofing encompasses a range of systems tailored to different building sizes, climates, and budgets. This article explains major commercial roof types, their performance characteristics, maintenance needs, and selection factors to help facility managers and building owners make informed decisions. Understanding the differences between membrane, metal, built-up, and green systems is key to long-term roof performance.

Roof Type	Typical Use	Key Benefit
Built-Up Roofing (BUR)	Low‑slope, large footprints	Durability and multi-layer redundancy
Modified Bitumen	Low‑slope, retrofit	Flexible, good for flashing details
EPDM	Flat roofs, low cost	Simple installation, proven track record
TPO	New construction, reflective needs	Energy efficiency, weldable seams
PVC	Industrial, chemical exposure	Chemical resistance, durability
Metal	Steeper slopes, long spans	Longevity and recyclability
Spray Polyurethane Foam (SPF)	Complex shapes, insulation focus	Seamless insulation and waterproofing
Green Roofs	Urban, stormwater management	Environmental benefits and insulation

Built-Up Roofing (BUR)

Built-Up Roofing, often called BUR or “tar and gravel,” consists of alternating layers of bitumen and reinforcing felts finished with a surfacing layer such as gravel. BURs are typically installed on low-slope commercial buildings and have a long industry history. BUR provides redundancy through multiple plies, improving puncture and UV resistance when properly maintained.

Typical service lives range from 20 to 30 years depending on materials, ply count, and maintenance. BUR performs well in heavy foot-traffic areas but can be heavier than alternative systems and requires trained crews for proper installation.

Modified Bitumen Roofing

Modified Bitumen membranes integrate polymer modifiers (SBS or APP) into asphalt to increase flexibility and temperature tolerance. They are supplied in rolls and can be installed using torches, hot asphalt, cold adhesives, or self-adhering sheets. Modified bitumen is a versatile choice for retrofit projects where enhanced flashings and seams are beneficial.

This system is suited to roofs needing improved elasticity over BUR while retaining familiar asphalt-based materials. Regular inspection of seams and flashings is essential to avoid moisture intrusion.

EPDM (Ethylene Propylene Diene Monomer)

EPDM is a synthetic rubber membrane typically supplied in large sheets and used on low-slope commercial roofs. It is known for ease of installation, low material cost, and proven performance in cooler climates. EPDM offers strong weathering resistance and can be ballasted, fully adhered, or mechanically fastened.

Seam adhesion quality and edge terminations determine long-term performance. EPDM is less reflective than TPO or PVC, so energy savings from solar reflectivity are limited unless coatings are applied.

TPO (Thermoplastic Olefin)

TPO membranes are single-ply thermoplastics known for white, reflective surfaces that improve roof albedo and cooling. TPO is welded at seams, creating strong, heat-fused connections. TPO is popular for energy-efficient new construction due to its reflective properties and seam weldability.

Performance varies by manufacturer and formulation; quality control during installation is crucial. TPO generally resists UV and ozone but has had variability in long-term performance across early-generation formulations.

PVC (Polyvinyl Chloride)

PVC single-ply roofing is durable, chemically resistant, and weldable at seams. It excels in environments with grease, oils, or chemical exposure, making it a common choice for restaurants and certain industrial buildings. PVC provides strong seam integrity and good long-term dimensional stability.

PVC membrane costs are typically higher than EPDM and some TPOs, but long service life and low maintenance often justify the premium for demanding applications.

Metal Roofing Systems

Commercial metal roofing includes standing-seam panels, corrugated sheets, and insulated metal panels. Metal roofs suit both low and steep slopes and are chosen for longevity, recyclability, and wind resistance. Metal roofing can last 40 years or more with proper fastening and finishes.

Considerations include thermal movement, noise during rain, and potential for galvanic corrosion where dissimilar metals contact. Metal panels may be installed over insulation or as part of insulated panel systems for high R-value requirements.

Spray Polyurethane Foam (SPF)

SPF is a spray-applied, seamless insulation and roofing layer that bonds to most substrates, providing continuous insulation and waterproofing in one step. SPF conforms to complex roof geometries and reduces penetrations. SPF delivers excellent insulation performance (high R-value) and a watertight continuous membrane when correctly installed and protected.

SPF requires protective coatings to shield foam from UV degradation. Skilled applicators are essential to avoid density or adhesion issues that shorten service life.

Green Roofs And Intensive Vegetative Systems

Green roofs incorporate vegetation layers over a roofing membrane and drainage system to provide stormwater management, urban heat island mitigation, and improved insulation. Systems range from lightweight extensive roofs to deeper intensive rooftop gardens. Green roofs extend membrane life by protecting it from UV and temperature extremes while adding ecological and social benefits.

Design complexity is higher due to load-bearing, irrigation, and long-term maintenance needs. Waterproofing and root barriers are critical to prevent leaks and membrane damage.

Cool Roof Coatings And Reflective Systems

Cool roof coatings are reflective layers applied to existing roofs to improve solar reflectance and reduce roof surface temperatures. Coatings are available for bituminous, metal, single-ply, and SPF systems. Applying a cool roof coating can lower building cooling loads and extend membrane life by reducing thermal cycling.

Coatings vary in durability and compatibility; selection should match substrate type and expected foot traffic. Recoating intervals typically range from 5 to 15 years depending on product and exposure.

Choosing The Right Commercial Roofing System

Selecting a system requires balancing budget, roof slope, climate, building use, expected lifespan, and maintenance capacity. Key selection factors include thermal performance (R-value), wind uplift resistance, membrane seam performance, and roof deck compatibility.

• Climate: Hot climates benefit from reflective membranes; cold climates may prioritize insulation and robust flashing details.
• Building Use: Kitchens and chemical exposure favor PVC; high foot traffic areas may need protective surfacing or walkway pads.
• Budget vs. Life Cycle Cost: Consider initial cost and expected service life including maintenance and replacement costs.

Installation, Inspection, And Maintenance Best Practices

Proper installation by certified contractors fundamentally affects performance more than product selection in many cases. **Quality control during flashing, seam welding, and edge terminations is essential.**

Implement a maintenance plan with semiannual inspections and after-severe-weather checks. Typical tasks include clearing drainage, repairing flashings, addressing ponding water, and recoating or patching as needed.

Cost And Life Expectancy Comparison

System	Typical Lifespan	Relative Installed Cost
BUR	20–30 Years	Moderate
Modified Bitumen	15–25 Years	Moderate
EPDM	20–30 Years	Low–Moderate
TPO	15–25 Years	Moderate
PVC	20–30+ Years	Moderate–High
Metal	30–60+ Years	High
SPF	20–30 Years	Moderate–High
Green Roof	20–50 Years (system dependent)	High

Regulatory, Sustainability, And Incentive Considerations

Local building codes, energy codes, and utility programs may influence roofing choices. Many jurisdictions and utility providers offer incentives for high-reflectance roofs, cool roof retrofits, or green infrastructure. Verifying code compliance and incentive eligibility before design finalization can reduce costs and accelerate approvals.

Specifiers should also consult standards from industry bodies such as the National Roofing Contractors Association (NRCA) and ENERGY STAR guidelines for cool roofs to align performance expectations.

When To Consult A Roofing Professional

Complex roof geometries, historic buildings, or projects requiring warranties and energy modeling should involve design professionals early. Expert input ensures proper substrate preparation, insulation strategy, and long-term maintenance planning. Engaging a certified roofing contractor and requesting references, warranty terms, and detailed scope reduces project risk.

For high-value roofs, consider performance roofing warranties and third-party inspections during construction to confirm compliance with specifications.

Key Takeaways For Building Owners

Selecting the right commercial roofing type depends on functional needs, climate, budget, and life-cycle goals. **Prioritize proper installation, a proactive maintenance plan, and alignment with local codes and sustainability incentives to maximize return on investment.**

For technical guidance, resources include the NRCA (https://www.nrca.net/) and the EPA’s guidance on cool roofs and green infrastructure; consult product manufacturers for system-specific performance data.