How Much Does Commercial TPO Roofing Cost Per Square Foot on the Eastside?

Commercial TPO roofing on the Eastside typically runs $8 to $14.50 per square foot, fully installed, based on Seattle-area contractor pricing. For a mid-size building, that works out to roughly $24,000 to $43,500 for a 3,000 square foot roof. Where a specific quote lands in that range depends mostly on membrane thickness, insulation package, and whether the job is a tear-off or a recover.

What the per-square-foot number actually includes

The $8 to $14.50 per square foot range is a fully installed figure, not a material-only number. It covers the TPO membrane itself, the insulation board underneath, fasteners or adhesive depending on the attachment method, and standard flashing work at parapets, drains, and rooftop penetrations. A quote that reads noticeably below this range is worth asking about directly, since it may be excluding one of those components rather than reflecting an unusually good price.

A real project example: 3,000 square feet

A 3,000 square foot commercial roof, a common size for a small retail strip, office building, or light industrial unit on the Eastside, typically totals $24,000 to $43,500 installed. At the simplest end of that range, that means a straightforward recover over sound existing insulation with minimal roof penetrations. At the top end, that usually means a full tear-off, new insulation to current energy code, and a roofline with multiple HVAC curbs, skylights, or drains that each need their own flashing detail.

What moves a quote within the range

Four factors most often explain why one TPO quote comes in low and another comes in high for a similarly sized roof:

1. Tear-off vs. recover. Removing the old roofing system down to the deck costs more upfront than installing TPO over sound existing insulation, but it is the only way to find and address any decking issues hiding underneath.
2. Insulation package. Buildings being brought up to current energy code requirements need a thicker insulation package than a like-for-like recover, which adds material cost.
3. Roof access and height. A single-story building with ground-level access to the roof costs less to work on than a multi-story building requiring crane-lifted material or extensive fall-protection setup.
4. Roofline complexity. Every HVAC unit, skylight, drain, and parapet wall the crew has to flash around adds labor time that a simple, open roof deck does not require.

TPO’s fit for the Eastside’s climate

Flat and low-slope commercial roofs on the Eastside deal with the same 60 to 65 inches of annual rain that drives residential moss growth in this area, which makes proper drainage detail and seam welding especially important on a TPO installation here. A well-installed TPO system with correctly sloped drainage and heat-welded seams handles that rainfall without the ponding-water problems a poorly detailed flat roof can develop over time.

Permits for a commercial reroof

A commercial reroof inside Issaquah city limits is applied for through MyBuildingPermit.com the same way a residential reroof is, though a commercial project is more likely to trigger a permit given its scale and the frequent involvement of insulation upgrades tied to energy code. King County DPER handles the equivalent process for commercial properties outside city limits on the Eastside.

What to budget

Plan on $8 to $14.50 per square foot as your working range for a TPO reroof, and ask any bidder specifically whether their number is a tear-off or a recover, since that single distinction usually explains more of the spread between two quotes on the same building than any other factor.