Flat roof replacement prices online range from a few dollars a square foot to more than twenty, and both ends are real. The number depends on which membrane goes on, what is under the old one, and how much of the building's insulation, drainage and flashing has to be rebuilt. Here are typical 2026 ranges for the Wausau area, what moves a quote, and how to compare bids that don't look alike.
Typical flat roof replacement costs
Want a number for your own building? Try our free flat and commercial roof cost calculator. It uses the same ranges as this table.
These are typical installed ranges per square foot for low-slope roofs in central Wisconsin, including the membrane, insulation, standard flashings and edge metal. Size, height, access and condition move the exact number. That is why a real quote comes after someone has been on the roof and taken a core sample.
| System | Typical installed cost | Notes |
|---|---|---|
| EPDM (rubber, black) | $5.50 – $11 / sq ft | Very common in cold climates; stays flexible far below zero |
| TPO (single-ply, white) | $6 – $12 / sq ft | Heat-welded seams; the most common new commercial roof nationally |
| PVC (single-ply) | $7 – $14 / sq ft | Grease- and chemical-resistant; restaurants and food plants |
| Modified bitumen | $5 – $10 / sq ft | Multi-ply and tough under foot traffic; common on small buildings |
| Recover over existing roof | $4 – $8 / sq ft | Only if the old roof is a single, dry layer |
| Silicone or acrylic coating | $2 – $5 / sq ft | Restoration, not replacement; needs dry insulation |
| Small residential flat roof | $2,500 – $7,000 per job | Porch, addition or garage; higher per sq ft |
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Wausau Superior Flat Roofing repairs, coats and replaces commercial and flat roofs across Wausau and central Wisconsin, with a written price before any work starts. Request a quote online and we’ll call you back.
What moves a commercial roofing quote
Tear-off versus recover
Removing the old roof and hauling it away is a large share of the labor. If the existing roof is one layer, its insulation is dry and the deck is sound, the building code generally allows one recover over it, which skips the tear-off. If the roof is wet or already has two layers, it has to come off. Our recover vs. replacement guide covers how that is decided.
Wet insulation and deck damage
Leaks that ran for years leave wet insulation, and sometimes a rusted steel deck or rotted wood deck. In a cold climate that wet insulation also freezes and thaws every winter, which breaks it down faster. Every square foot of it gets replaced. A moisture survey before the quote tells you how much there is, so it doesn't turn up as a change order halfway through.
Insulation and energy code
When a roof is replaced, the energy code usually requires the new roof to meet today's insulation levels, which in a northern climate are much thicker than what went on decades ago. More insulation means more material, taller edges and curbs, and sometimes raised rooftop units. It also means lower heating bills and less snowmelt from heat escaping through the roof, which is one of the causes of ice at the drains.
Drainage fixes
If the old roof ponded, the new one should not. Tapered insulation, crickets between drains, or added drains and scuppers cost more up front and save the new roof from the same early failure, and from the ice that forms where water sits. See ponding water on a flat roof.
Penetrations, edges and access
Every rooftop unit, vent, pipe, skylight and hatch needs its own flashing. A plain warehouse roof with a few units costs less per square foot than a smaller roof crowded with equipment and parapet walls. Building height, crane needs and where the dumpster can sit all matter too.
Season
Most re-roofing in central Wisconsin happens from about April through November. Work in deep cold is possible with the right products, but it is slower. Planning ahead gets you a better slot and a calmer job.
How to compare bids that don't match
- Same scope? Check that every bid includes tear-off (or not), the same insulation thickness, new flashings at every wall and curb, and the same edge metal.
- Wet insulation: does the bid include an allowance, a unit price per square foot, or nothing? "Nothing" often becomes a change order.
- Membrane thickness and attachment: a thicker membrane, fully adhered, costs more than a thinner one mechanically attached, and performs differently.
- Warranty: is it the contractor's workmanship warranty, a manufacturer's material warranty, or a manufacturer's full system warranty? They are very different.
- Permits and paperwork: on a home, ask whether the contractor will take out any required permit. In Wisconsin, a contractor who obtains a building permit for a one- or two-family home must hold the state's Dwelling Contractor certification.
Why small flat roofs cost more per square foot
Setup, edge metal and the flashing where the roof meets the house cost about the same whether the roof is 200 square feet or 2,000. On a porch, garage or addition, those fixed costs dominate, so the per-square-foot price is higher even though the total is small. Fixing the wall flashing and the slope properly is what makes a small flat roof stop leaking, so it is the last place to cut corners. See residential flat roof replacement.