As of October 2026, one 2026 Florida cost guide estimates a 600 sq ft detached ADU in Tampa at about $88,000 basic, $134,000 mid-range and $210,000 high-end. Garage conversions usually come in lower. Flood elevation, sewer and electrical work, and fees decide where a given lot ends up.
What do the published numbers say?
No public source we found tracks finished Tampa ADU prices. The closest estimates, as of October 2026:
- Detached, 600 sq ft, Tampa: $88,000 basic, $134,000 mid-range, $210,000 high-end (CostToBuildHouse, 2026).
- Detached, 600 sq ft, St. Petersburg: $84,000 basic, $128,000 mid-range, $200,000 high-end (same guide).
- Garage conversion, Florida: $60,000 to $145,000 (same guide).
- Attached, national: $125 to $225 per sq ft (HomeGuide).
The Florida guide gives no underlying data, so read these as rough benchmarks, not bids.
Which costs are specific to Tampa Bay?
- Elevation. On a flood-zone lot, a raised slab or stem wall, fill and steps.
- Wind. Straps, anchors and rated windows and doors under the Florida Building Code.
- Utilities. Panel upgrades, sewer laterals, and septic evaluation in parts of Hillsborough.
- Fees. St. Petersburg cites roughly $1,020 in permit fees for an 800 sq ft ADU with one bath. Impact fees vary by jurisdiction.
Can size choices lower the price?
Yes. Fewer bathrooms, a simple roof shape and fewer large openings all reduce cost. Staying under a jurisdiction's size cap also avoids the need for a variance.
Why do two similar ADUs get very different prices?
It depends on the site. A lot outside the flood zone with a modern electrical panel and sewer at the alley will price far lower than a low lot that needs fill, a new service and a long sewer run. That is why our price follows a site visit, in writing.
Related
Sources, as of October 2026: CostToBuildHouse, "2026 Florida ADU Cost Guide"; HomeGuide, "How much does it cost to build an ADU?"; City of St. Petersburg ADU page. All figures are outside estimates; our own price follows a site visit.
Updated October 2026