Commercial roofing · Ohio & Michigan
TPO roofing for low-slope commercial roofs
What TPO single-ply membrane is, how it is attached, and the decisions a property manager faces at replacement time in Ohio and Michigan.
2 min read · Updated
Key takeaways
- TPO is a white, heat-welded single-ply membrane widely used on low-slope commercial roofs.
- How it is attached and how much insulation goes under it drive most of the price.
- Get the thickness, attachment, insulation and warranty in writing so bids are comparable.
TPO (thermoplastic polyolefin) is a single-ply roofing membrane used on many low-slope commercial roofs. It comes in rolls, usually white, and the seams are joined with hot air (heat-welded) rather than glued.
How it is attached
- Mechanically attached: fasteners and plates hold the membrane and insulation to the deck, with the fasteners hidden in the seam laps.
- Fully adhered: the membrane is glued to the insulation or cover board.
- Induction-welded: plates are fastened first, then the membrane is bonded to them from above.
The attachment method depends on the deck, wind design, building height and the manufacturer’s approved assemblies.
What changes a TPO replacement scope
- Wet insulation. A moisture survey finds saturated insulation that must come out. Replacing only the membrane over wet insulation traps water.
- Insulation requirements. When a low-slope roof is replaced, the energy code can require insulation to be brought up to the current requirement. Manufacturer and industry summaries report continuous insulation of about R-30 above the deck in climate zone 5 under the current Ohio code, and in zones 5 and 6 under Michigan’s 2021 commercial energy code. Confirm the exact requirement and any exceptions with your building official before bidding.
- Drainage. Ponding water often needs tapered insulation, crickets or drain work.
- Details. Curbs, penetrations, parapets, edge metal and rooftop equipment often take more labor than the open field.
- Access and occupancy. Crane lifts, occupied buildings and after-hours work all affect schedule and cost.
Repair, coat, recover or replace?
A newer TPO roof with isolated seam or flashing problems is usually a repair. An aging but dry and sound TPO roof may be a candidate for a manufacturer-approved coating. A roof with widespread wet insulation or failed membrane usually needs a recover or full replacement. See repair, coating, recover or replacement.
What to ask for in a proposal
- Membrane thickness, manufacturer and the exact assembly (insulation type and thickness, cover board, attachment).
- Warranty type (material only, or system/NDL) and who issues it.
- How much wet insulation is included, and the unit price for more.
- Drainage corrections.
- Edge metal, flashing and curb details.
Use the commercial inspection intake to organize your roof zones before a site visit.
A TPO maintenance checklist
- Inspect every spring and fall, and after hail or wind storms.
- Look for open or loose welds at seams, corners and flashings.
- Clear drains and note ponding.
- Keep foot traffic on walk pads around equipment.
- Record leaks with the date, weather and interior location in the inspection intake.
Use the commercial roof cost planner to compare an inspection program, a maintenance plan, coating and replacement from your roof area, and send the scope to bidders with the RFP generator.
Run your numbers
Quick commercial roof estimate
Provisional planning range (our setting, not a quote or market average). Real prices depend on condition, access and scope.
TPO roofing for low-slope commercial roofs: common questions
How long does a TPO roof last?
It varies with thickness, formulation, installation and maintenance. Many owners plan for roughly 15 to 25 years, but inspections and repairs keep it at the upper end.
Is thicker TPO worth it?
Thicker membranes have more material over the reinforcing scrim, which can add durability and often qualifies for longer warranties. Compare thickness on every bid.
Can TPO be installed over an existing roof?
Yes, as a recover, if the existing roof is dry and codes allow another layer. A cover board is usually installed first.
Does a white TPO roof help with energy costs?
A reflective roof reduces heat gain in summer, which can lower cooling costs. In Ohio and Michigan the winter effect is smaller because snow cover and low sun angles reduce the difference.
Sources
- Ohio commercial roof insulation requirements (2024 Ohio Building Code, Chapter 13) — manufacturer bulletin, Holcim Elevate. Manufacturer
Secondary summary of the energy code. Confirm the requirement with your building official. - Michigan code books and effective dates, Michigan Department of Licensing and Regulatory Affairs (LARA), Bureau of Construction Codes. State government
- Roof coating vs. commercial replacement, GAF. Manufacturer
General information only. Codes, product instructions and warranties change, and your local building department and the manufacturer have the final word.