When building owners begin planning a commercial roof replacement, the first question is almost always the same: how much will it cost? The answer, as any experienced roofing contractor will tell you, is that it depends. Commercial roofing costs are not determined by a single variable but by the interaction of multiple factors that are unique to each project. Two buildings of the same size sitting side by side can have dramatically different replacement costs based on the systems involved, their existing conditions, and the work required.
At Windward Roofing & Construction, we have estimated and completed thousands of commercial roof replacements since 1984. Over those four decades, we have developed a clear understanding of the factors that drive project costs and how building owners can make informed decisions about their roofing investments. This guide breaks down the nine key variables that determine what you will pay for your commercial roof replacement.
Factor 1: Roof Size and Square Footage
The most obvious cost driver is the total area of the roof. Commercial roofs are measured in square feet, and virtually every component of the estimate, from membrane to insulation to labor, is priced on a per-square-foot basis. A 50,000-square-foot warehouse roof will cost significantly more in total than a 5,000-square-foot retail building, simply because there is ten times more material and labor involved.
However, per-square-foot costs typically decrease as roof size increases. This economy of scale exists because certain fixed costs, including equipment mobilization, project management, permit fees, and crane rental, are spread over a larger area. Material suppliers also offer volume pricing on large orders. As a result, a building owner with a very large roof often benefits from a lower per-square-foot cost compared to a small building owner using the same roofing system.
For budgeting purposes, commercial roof replacement costs in the Midwest generally fall between $5.50 and $18.00 per square foot fully installed, depending on the system type and the other factors discussed below.
Factor 2: Roofing Material and System Type
The roofing system you choose is the second most significant cost variable. Each commercial roofing system has a different material cost, labor requirement, and expected lifespan, which together determine the initial investment and the long-term cost of ownership.
EPDM (Ethylene Propylene Diene Monomer) is typically the least expensive single-ply option, with installed costs ranging from approximately $5.50 to $8.50 per square foot. Its lower material cost and straightforward installation make it an attractive choice for budget-conscious building owners, particularly on large roof areas.
TPO (Thermoplastic Polyolefin) costs slightly more than EPDM, generally $6.00 to $10.00 per square foot installed. The premium reflects TPO's energy-efficient reflective surface and its heat-welded seam technology, which provides superior waterproofing performance.
Modified bitumen systems range from approximately $7.00 to $11.00 per square foot. The multi-layer construction and labor-intensive application methods account for the higher cost, but modified bitumen provides excellent puncture resistance and proven performance in harsh climates.
Built-up roofing (BUR) falls between $8.00 and $14.00 per square foot. The multiple layers of asphalt and reinforcing fabric create a robust, redundant waterproofing system, but the material and labor costs are higher than single-ply alternatives.
Metal roofing is typically the most expensive option for commercial applications, ranging from $10.00 to $18.00 per square foot or more depending on the metal type and profile. Standing seam systems cost more than exposed-fastener panels, and premium metals like copper or zinc push costs even higher. However, metal's exceptional longevity of 40 to 60 years or more can deliver excellent value when measured on a per-year-of-service basis.
Factor 3: Roof Access and Logistics
How easily contractors and materials can access your roof has a meaningful impact on project cost. Buildings that present logistical challenges require more time, equipment, and planning, all of which add to the estimate.
Building height affects material handling costs. A single-story warehouse where materials can be loaded directly from a flatbed truck onto the roof is far less expensive to service than a five-story office building where every piece of insulation and roll of membrane must be craned or hoisted to the roof level.
Site access matters as well. Urban buildings with narrow lots, no adjacent staging areas, and street parking restrictions create challenges that rural or suburban buildings with open lots and easy truck access do not face. In downtown Chicago, for example, contractors may need to coordinate with the city for lane closures, schedule deliveries during off-peak hours, and use smaller vehicles to navigate tight spaces.
Occupied buildings add complexity because work must be coordinated around building operations, tenant schedules, and noise restrictions. Phased construction, after-hours work, and additional safety precautions for occupied buildings all increase labor costs compared to working on a vacant structure.
Factor 4: Existing Roof Layers and Tear-Off Requirements
What is already on your roof significantly affects the cost of putting a new one on. The condition and composition of the existing roofing system determine whether a simple recover is possible or whether a full tear-off is required.
Full tear-off involves removing the existing roofing membrane, insulation, and sometimes the vapor barrier down to the structural deck. This is the most expensive approach but provides the opportunity to inspect and repair the deck, install new insulation to current energy code requirements, and start fresh with a complete new system. Tear-off costs include labor for removal, disposal fees for hauling the old material to a landfill, and potential hazardous material abatement if asbestos-containing materials are present in older roofing systems.
Recover or overlay involves installing the new roofing system directly over the existing one, typically with a layer of new insulation between them. This approach saves the cost of tear-off and disposal and can reduce the project timeline significantly. However, a recover is only appropriate when the existing roof has only one layer, the existing insulation is dry, the structural deck can support the additional weight, and local building codes permit the additional layer. Most building codes limit roofs to a maximum of two total layers.
When a recover is feasible, it can reduce total project costs by 20 to 30 percent compared to a full tear-off and replacement.
Factor 5: Insulation Type and R-Value Requirements
Roof insulation represents a significant portion of the total project cost, and current energy codes may require substantially more insulation than what exists on an older building. Understanding insulation costs is essential for accurate budgeting.
Energy code requirements. Current energy codes, including the International Energy Conservation Code (IECC) adopted by most Illinois municipalities, specify minimum roof insulation R-values based on climate zone. For most of Illinois, which falls in Climate Zone 5, the current minimum continuous insulation requirement for commercial roofs is R-30. Many older buildings have R-15 to R-20 of existing insulation, meaning a code-compliant replacement must include additional insulation.
Insulation types and costs. Polyisocyanurate (polyiso) is the most common commercial roof insulation, offering an R-value of approximately 5.7 per inch. Expanded polystyrene (EPS) provides about R-4.2 per inch at a lower per-board-foot cost. Extruded polystyrene (XPS) offers approximately R-5.0 per inch and superior moisture resistance. The type and thickness of insulation needed for your project will significantly affect the total cost.
Tapered insulation systems. If your roof has drainage deficiencies, tapered insulation can be used to create proper slope for water flow toward drains and scuppers. Tapered systems cost more than flat insulation because they require custom engineering and more material, but they solve ponding water problems that can dramatically shorten a roof's service life.
Factor 6: Drainage Design and Modifications
Proper drainage is essential for any commercial roof, and modifications to the drainage system can add meaningful cost to a replacement project.
Existing drainage adequacy. If the existing roof drains effectively and the internal drains, scuppers, or gutters are in good condition, drainage costs during replacement may be limited to simple reconnection and sealing. However, if the existing system has ponding water problems, inadequate drain capacity, or deteriorated drainage components, modifications become necessary.
Additional drains or scuppers. Adding new roof drains or scuppers to address ponding water or improve drainage capacity requires plumbing work, structural penetrations, and interior piping that add several thousand dollars per drain to the project cost. Despite the expense, additional drainage often solves chronic problems that have plagued a building for years.
Gutter and downspout replacement. On buildings with perimeter gutters, the condition of the gutter system should be evaluated during the roof replacement. Deteriorated gutters and downspouts are best replaced at the same time as the roof to avoid having to mobilize a contractor again shortly after the roof project is complete.
Factor 7: Permits and Code Compliance
Building permits and code compliance requirements add both direct and indirect costs to commercial roofing projects.
Permit fees. Commercial building permits for roofing projects typically range from a few hundred dollars for small projects to several thousand dollars for large ones. Fees vary by municipality and are usually calculated based on project value or square footage.
Code-triggered upgrades. In many jurisdictions, a roof replacement triggers requirements to bring the roof into compliance with current energy codes, fire codes, and wind uplift standards. These requirements can mandate increased insulation, specific fire-rated assemblies, enhanced fastening patterns, or upgraded edge securement systems. While these upgrades add cost to the project, they also improve the building's performance and safety.
Inspections. Permit inspections during and after construction require coordination with the local building department and may affect the project schedule. Your contractor should factor inspection timing into the project plan and handle all coordination with municipal inspectors.
Factor 8: Geographic Location and Labor Market
Where your building is located affects roofing costs in several ways.
Labor rates. Commercial roofing labor costs vary by region. Projects in the Chicago metropolitan area generally carry higher labor rates than those in smaller cities or rural areas. Union labor, which is common on larger commercial projects in the Chicago area, tends to cost more per hour than non-union labor but often delivers higher productivity and consistency. The prevailing wage requirements on publicly funded projects further increase labor costs.
Material transportation. Roofing materials are heavy and expensive to ship. Buildings located far from major distribution centers or manufacturers may face higher material delivery costs. Most of Illinois is well-served by roofing material distributors, but remote locations can see a cost premium for delivery.
Climate-related requirements. As discussed earlier, Illinois climate conditions drive specific design requirements including enhanced wind uplift resistance, adequate snow load capacity, and increased insulation R-values. These climate-driven specifications add cost compared to buildings in milder climates.
Factor 9: Contractor Selection and Warranty Level
The contractor you choose and the warranty level you select have a direct impact on project cost and long-term value.
Contractor quality and pricing. Commercial roofing contractors span a wide range in terms of experience, capability, and pricing. Established, manufacturer-certified contractors with strong safety records and comprehensive insurance typically charge more than newer or less-qualified firms. However, the additional cost reflects the quality of workmanship, the strength of their warranty, and the reduced risk of problems during and after construction.
Warranty tiers. Most commercial roofing projects offer multiple warranty options at different price points. A basic material-only warranty is included at no additional cost. A standard system warranty covering materials and labor for 15 to 20 years adds a modest premium. A No Dollar Limit (NDL) warranty covering all costs for 20 to 30 years represents the highest level of protection and the greatest additional expense, typically $0.15 to $0.50 per square foot above the standard warranty cost.
The value perspective. When evaluating contractor pricing, consider the total cost of ownership rather than just the initial price. A contractor who installs a quality system with a strong warranty and provides responsive support for decades delivers far more value than a low-cost alternative that leads to premature failure, denied warranty claims, or a contractor who is no longer in business when you need them.
Getting an Accurate Estimate for Your Building
The only way to get an accurate cost estimate for your specific commercial roof replacement is to have qualified contractors assess your building in person. No website, calculator, or rule of thumb can account for the unique combination of factors that determine your project's cost.
When soliciting estimates, provide each contractor with the same project parameters and request itemized proposals that break down costs by component. This allows you to make meaningful comparisons and understand exactly what you are getting for your investment.
At Windward Roofing & Construction, we provide detailed, transparent estimates that clearly explain every cost component. Our estimators personally visit your site, assess the existing conditions, and present options that align with your budget and performance requirements. We serve building owners and general contractors across the Chicago metropolitan area and throughout Illinois, with the capacity to handle projects from new construction to complex multi-building replacements.
Ready to understand the true cost of your commercial roof replacement? Contact Windward Roofing for a free, no-obligation assessment and estimate. Our team will evaluate your building and provide a comprehensive proposal that accounts for all nine factors discussed in this guide.
Frequently Asked Questions
Commercial roof replacement costs typically range from $5.50 to $18.00 per square foot fully installed, depending on the system type and project variables. TPO systems generally cost $6.00 to $10.00 per square foot, EPDM runs $5.50 to $8.50, modified bitumen costs $7.00 to $11.00, built-up roofing ranges from $8.00 to $14.00, and metal roofing costs $10.00 to $18.00 or more. These ranges include membrane or surface material, insulation, flashings, labor, tear-off, and disposal.
Yes, larger commercial roofs typically cost less per square foot than smaller ones. This is because fixed costs like equipment mobilization, permit fees, and project management are spread over a larger area, and material suppliers often offer volume discounts for large orders. A 100,000-square-foot warehouse roof will generally have a lower per-square-foot cost than a 5,000-square-foot retail building roof using the same system.
A recover, where the new roofing system is installed over the existing one, can save 20 to 30 percent compared to a full tear-off and replacement. However, a recover is only appropriate when the existing roof has one layer, the insulation is dry, the deck is structurally sound, and local building codes permit it. Most building codes limit roofs to two layers. A recover over wet insulation or a compromised deck will lead to premature failure of the new system.