Flat Roof Repair & Membrane Cost Calculator

Targeted flat roof repairs cost between $2.50 and $7.50 per square foot, with most homeowners and commercial building managers paying $450 to $1,500 per localized repair. Minor puncture patches cost $350 to $600, split seam re-welding costs $500 to $900, while severe ponding water corrections and wet polyiso insulation tear-outs range from $1,200 to $3,500.

100% High-Solids Silicone coatings and PVC membranes offer the highest resistance to standing water. Unlike acrylic coatings or asphalt modified bitumen systems which hydrolyze and peel when submerged, inorganic silicone polymers are chemically unaffected by ponding water. However, correcting slope with tapered polyisocyanurate crickets or adding roof drains is the permanent structural solution.

No. EPDM is a thermoset synthetic rubber that cannot be heat-welded. TPO is a thermoplastic olefin that fuses under hot air. Patching an EPDM roof requires solvent-based primer, uncured EPDM flashing tape, and lap sealant. Attempting to heat-weld TPO to EPDM will fail to create a molecular bond and lead to immediate leak failure.

A properly installed flat roof patch performed to ASTM standards (cleaned with solvent conditioner, primed, and heat-welded or pressure-rolled with uncured flashing) will last 10 to 15 years, matching the remaining lifespan of the surrounding membrane.

Wet polyisocyanurate insulation beneath a flat roof produces a distinct squishy or spongy sensation when walked on, creates trapped bubbling blisters in hot sunlight, and can be definitively identified using non-destructive infrared thermography or electrical capacitance moisture impedance meters during a professional roof survey.