What Drives TPO Roofing Cost
TPO is priced by the square foot, and the membrane itself is rarely the biggest line. Insulation, attachment and what is underneath move the number far more than the brand on the roll.
The five variables that set the price
- Membrane thickness — 45, 60 or 80 mil. 60 mil is the commercial default; 80 mil buys puncture resistance where there is foot traffic
- Insulation — polyiso thickness to meet the required R-value, which is often the single largest material cost
- Attachment — mechanically fastened is cheapest, fully adhered handles wind uplift and looks flatter, induction-welded sits between them
- Tear-off depth — one old membrane, or three layers plus a wet lightweight deck
- Details — every curb, drain, scupper, skylight, pipe and parapet is hand-flashed labour, and a cluttered roof costs more per square foot than a clear one
Where flat roof quotes diverge wildly
Two bids on the same building can differ by 40% because one includes a full tear-off and code-required insulation while the other is a recover over the existing membrane. Both are legitimate approaches with very different service lives.
Before comparing numbers, make both bidders state membrane thickness in mils, insulation R-value, attachment method, warranty type and length, and whether the existing system is being removed.
Recover or tear off
A recover is permitted when the existing system is dry and the code limit on layers has not been reached. It is cheaper and faster. If moisture is trapped in the insulation it must come out, because water under a new membrane never dries and the insulation loses its R-value permanently.
An infrared or core-cut moisture survey answers this before a bid, not after.
Common questions
Is TPO cheaper than PVC?
Generally yes, per square foot of material. PVC holds an advantage where grease or chemical exposure is a factor — restaurant exhaust in particular degrades TPO. For a typical Sacramento warehouse or office, TPO is the cost-effective choice.
Why is insulation such a large part of the cost?
Because a re-roof that adds or replaces insulation must meet the code R-value for the climate zone, and polyiso is priced by thickness. On a large roof the insulation can exceed the membrane cost.