Flat roof replacement cost

Flat roof replacement cost depends on your roof's size, slope and the crew that climbs it, so the range on this page is a start, not a bid. Call (855) 812-6217 during business hours with your ZIP code and ask for flat roof replacement cost quotes, and licensed roofers near you price it. Quotes cost nothing and you hire only if you want to.

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A flat roof replacement costs about $8.04 to $10.29 per sq ft for a membrane system, by Homewyse's May 2026 national figure. Angi puts a 1,500 sq ft TPO roof at $6,500 to $24,000, about $10,700 on average.

Ken has a 1,500 sq ft flat roof over a 1960s addition. Water sits in one corner after rain. His three quotes ran from $6,500 to $24,000, and he wants to know why.

Flat roof replacement cost per square

Low-slope roof prices, checked October 2026
Measure	Price	Source
Membrane installed per sq ft	$8.04 to $10.29	Homewyse, May 2026
TPO, 1,500 sq ft roof	$6,500 to $24,000	Angi, 2026
TPO national average	$10,700	Angi, 2026
Insulation board per sq ft	$1.60 to $15	Angi, 2026

Ken's wide spread comes mostly from insulation. One quote kept his old boards, and another added new tapered boards to drain the corner. See Angi's TPO cost guide and the Homewyse membrane estimate.

TPO, EPDM and modified bitumen

TPO. A white sheet with heat-welded seams. Reflects sun, the most common choice now.
EPDM rubber roof. A black rubber sheet glued at the seams. Simple to patch.
Modified bitumen. Rolled asphalt sheets, torched or glued down. Tough under foot traffic.

Ask each roofer which one they install most. A crew that welds TPO every week does better seams than one that does it twice a year.

How long it lasts

Nationwide gives rubber roofs up to 50 years with care. Ponding water is the main thing that ends a flat roof early. Tapered insulation that slopes toward a drain fixes that.

The life range is on Nationwide's roof list.

Low-slope rules

ENERGY STAR counts any roof at 2:12 (9.5 degrees) or flatter as low slope. Shingles are not made for that pitch, so these roofs need a membrane. White membranes can qualify for ENERGY STAR cool roof ratings.

The low-slope cutoff is from ENERGY STAR.

The calculator's lowest slope is 4/12, which slightly overstates a dead-flat roof. Use the result as a top-end check. See also roof repair cost for patch prices.

Questions people ask

Is it cheaper to replace a flat roof?

Per sq ft, a flat roof often costs less than tile or slate and more than basic shingles. Homewyse puts membranes at $8.04 to $10.29 per sq ft. Insulation boards added on top of the deck raise the bill.

How often do flat roofs need replacing?

Rubber roofs can last up to 50 years by Nationwide’s count when the seams are kept up. Ponding water and foot traffic shorten that.

Is flat roofing cheaper than shingles?

Not usually per sq ft. Shingles start lower at $3.44. But flat roofs are often small additions, so the total bill can be lower.

Flat roof replacement cost per square foot?

About $8.04 to $10.29 for a membrane system, by Homewyse in May 2026. Angi’s TPO example works out to about $4 to $16 on a 1,500 sq ft roof.

Sources

Last checked October 2026

What to do now

Run the calculator with your own footprint, slope and material, and write down low, likely and high.
Call (855) 812-6217 with your ZIP code and the likely number, or send the job below. The Roof Cost Guide team answers during business hours and matches it with licensed roofers near you.
Compare three written quotes line by line against your band before you sign anything.

Talk to a local roofer

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Outside business hours, send the quote form and a roofer calls you back.

Three local quotes, one request

Send the flat roof replacement cost job with your ZIP code, roof size and the material you want. Up to three licensed roofers near you quote the same job, and we send your details to them and no one else. Quotes cost nothing and you hire only if you want to.