EXTERIOR
How to Estimate a Flat Roof (TPO/EPDM)
Contractor method to estimate a flat roof by membrane, area, insulation, seams, deck prep and install with clear materials and labor lines.
A flat roof is priced by area and membrane type, and the insulation, seams and deck prep all add lines. TPO and EPDM are the common choices, and each has its own install rhythm. This guide covers measuring the roof, choosing the membrane, and pricing the seams and prep.
THE SHORT ANSWER
How to Estimate a Flat Roof (TPO/EPDM)
1,000 sq ft of TPO with insulation, seams, deck prep and install at $3/sq ft totals about $8,600.
Measure the roof and count the seams
Price by the roof area, and remember seams are where flat roofs fail. Fewer, larger sheets mean fewer seams to weld or glue.
- Roof area
- Membrane type
- Insulation
- Deck prep
TPO vs EPDM
TPO is heat-welded, reflective and popular; EPDM is a rubber sheet that is glued or ballasted. Each has different material and labor costs.
Insulation and taper
Insulation boards and tapered panels that move water to the drains add cost but make the roof last. Confirm what the quote includes.
Deck prep and removal
A clean, dry deck is required before membrane. If the old roof has to come off, add removal and disposal to the bid.