ARX Roofing & Exteriors
    By ARX Roofing & Exteriors

    TPO, PVC, EPDM, Modified Bitumen, or Built-Up? Commercial Flat Roof Systems Compared

    The five common commercial flat roof systems are TPO, PVC, EPDM, modified bitumen, and built-up roofing. All five can keep a low-slope building dry. The right one depends on the building's use, what is on the roof, how the existing roof is built, and who will maintain it, so the choice should follow an inspection rather than a brand preference. Prices and lifespans vary by manufacturer, thickness, and installation quality, so ask for them in writing for your specific building.

    The five systems at a glance

    SystemWhat it isHow seams are madeOften considered when
    TPOSingle-ply thermoplastic membrane, usually whiteHeat-weldedA reflective, welded single-ply is wanted
    PVCSingle-ply thermoplastic membraneHeat-weldedGrease, oils, or chemical exhaust reach the roof, such as restaurants
    EPDMSingle-ply synthetic rubber membrane, usually blackTape or adhesiveA simple, repair-friendly rubber membrane is wanted
    Modified bitumenAsphalt-based sheets with polymer modifiers, in layersTorch, adhesive, or self-adheredAdded toughness and redundancy are wanted
    Built-up (BUR)Alternating layers of bitumen and reinforcing fabric, often with a gravel surfaceLayered in placeA multi-layer, traditional assembly is wanted

    This table describes general characteristics. A manufacturer's specification for your roof governs, not this table.

    What actually drives the choice

  1. What is on the roof. Heavy foot traffic from HVAC service, rooftop equipment, and exhaust affects how durable the surface needs to be.
  2. What the existing roof is. The existing system, its insulation, and its condition decide whether a recover is possible or a tear-off is required. See our guide on repair, restore, or replace for the code limits on recovers.
  3. Drainage and ponding. A flat roof that holds water shortens the life of almost any membrane. Fixing slope and drains can matter more than the membrane brand. See our guide to flat roof drainage and ponding water.
  4. Seams and flashings. Most leaks on flat roofs start at seams, flashings, and penetrations, not in the middle of the field. Ask who is responsible for those details and how they are inspected.
  5. Warranty terms. Manufacturer warranties differ in coverage, exclusions, and what they require of the installer and the owner. Read the actual warranty document before you sign.

    6. Questions to ask before you approve a bid

    1. Which system is proposed, and which manufacturer's specification is it installed to?

    2. Is this a tear-off or a recover, and what are the findings that support it?

    3. How will drainage and ponding be handled?

    4. How are seams, flashings, and penetrations detailed?

    5. What warranty applies, who issues it, and what does it exclude?

    6. How will tenants, access, and working hours be handled?

    7. Is the contractor licensed in North Carolina? ARX holds General Contractor license #108723, Building classification. Verify any contractor at nclbgc.org.

    Where to start

    Send ARX the building address, what you are seeing, and the roof system if you know it. ARX inspects the roof and follows with a written scope and price for repair, restoration, or replacement. See commercial roofing in Charlotte, or for apartments, condos, and townhomes, multifamily roofing. The Instant Estimate tool on this site is for homes only.

    Frequently Asked Questions

    Is TPO or PVC better? Neither is better in every case. Both are heat-welded single-ply membranes. PVC is often considered where grease or chemical exhaust reaches the roof. The deciding factors are what is on the roof and the manufacturer's specification.

    Can a new flat roof go over the old one? Sometimes. The building code limits recovers where the existing roof is wet or already has multiple layers. An inspection that checks for moisture settles it.

    Why do flat roofs leak at the seams and edges? Seams, flashings, and penetrations are where different materials meet and move. They are the most common leak points, which is why inspections focus there.

    Does ARX work on all of these systems? ARX repairs, restores, and replaces roofs on all types of commercial buildings, including flat and low-slope roofs. Call (704) 313-8834 or send a request online.

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