Flat Roof / Membrane Calculator

Enter your roof dimensions to estimate TPO, EPDM, or modified bitumen membrane rolls, plus insulation, adhesive, seam tape, and termination bar — with a full cost comparison.

Membrane Type

Membrane Thickness

Roof Length (ft)

Roof Width (ft)

Parapet Perimeter (ft)

Waste Factor (%)

Default parapet perimeter = 2 x (length + width) = 200 ft. Edit for irregular shapes.

Pricing (edit to match local rates)

TPO Roll (10x100 ft)

EPDM Roll (10x100 ft)

Mod-Bit Roll (3x33 ft)

Seam Tape Roll ($)

Adhesive 5-gal ($)

Term Bar 10 ft ($)

Insulation Sheet ($)

Roof Preview

Hover for details • not to scale

Roof Area (w/ waste)

2640 sq ft

2,400 sq ft + 10% waste

TPO Rolls

3 rolls

10 x 100 ft each

Adhesive

6 buckets

27 gal total (5-gal buckets)

Insulation (Polyiso)

83 sheets

4 x 8 ft (32 sq ft each)

Termination Bar

20 bars

200 ft perimeter, 10 ft bars

Best Total Cost

$6,575.00

EPDM (membrane + materials)

Purchase Option	Quantity	Est. Cost
TPO	3 rolls (10x100 ft)	$6,875.00
EPDMBest value	3 rolls (10x100 ft)	$6,575.00
Modified Bitumen	27 rolls (3x33 ft)	$7,070.00

Cheapest option: EPDM at $6,575.00Total includes membrane rolls, seam tape, bonding adhesive (6 buckets), polyiso insulation (83 sheets), and termination bar (20 pcs). TPO and EPDM are the most common single-ply systems for commercial flat roofs. Modified bitumen is typically used for smaller or residential low-slope applications.

This is a material estimate only. Actual roll counts depend on roof geometry, penetrations, and seam layout. Always consult your membrane manufacturer for coverage rates and warranty requirements.