St. Augustine, FL · St. Johns County
Home Addition in St. Augustine, FL: Cost & Permits
What home addition actually costs in St. Augustine, whether you need a permit, which inspections apply, and how long the job takes.
Verified August 2026
Typical local cost
$105,000
$45,000 – $280,000
per sq ft of added space
$200 – $450
Permit fee
$800 – $6,000
St. Johns County estimate
vs national
0%
local labor & materials
Do you need a permit for home addition in St. Augustine, FL?
Yes
Yes — a permit is required for home addition in St. Augustine, FL. The work must be inspected before it can be closed out, and a licensed contractor generally has to pull the permit.
Historic district properties face additional design review that can add weeks to exterior projects.
Cost breakdown in St. Augustine
| Low endSimple scope, competitive bid | $45,000 |
|---|---|
| TypicalMost homeowners land here | $105,000 |
| High endComplex access, premium materials | $280,000 |
| per sq ft of added space | $200 – $450 |
| Permit fee estimate | $800 – $6,000 |
| Timeline | 3-6 months of construction, 6-14 months including design and permitting |
Math: national baseline $45,000–$280,000 × St. Augustine cost index 1.00. Permit fees use a 1.00 local multiplier. Estimates, not quotes.
What drives your price here
- Added square footage and whether it is one or two stories
- Foundation type and site conditions
- Extending or adding HVAC capacity
- Zoning setbacks, lot coverage and impact fees
- Flood zone elevation requirements
Permit process and inspections
| Permit required | Yes |
|---|---|
| Who pulls it | Licensed contractor |
| Inspections | Foundation / slab inspection, Framing and sheathing, Electrical, plumbing and mechanical rough, Insulation and energy, Final building inspection |
| Documents | Building permit application, Sealed architectural and structural drawings, Site plan and survey showing setbacks, Energy code compliance forms, Notice of Commencement recorded with the county, Contractor license and insurance |
| Apply | St. Augustine permit portal |
Frequently asked questions
How long does an addition permit take in Florida?
Plan review for an addition typically runs four to twelve weeks depending on the jurisdiction, and that is after the sealed drawings are complete. Coastal and flood-zone properties take longer because of elevation review.
Do impact fees apply to a home addition?
Many Florida counties assess impact fees on added conditioned square footage. The fee is usually calculated per square foot and can add thousands to a large addition, so ask for the fee estimate before design.
Addition costs in nearby cities
Sources
Sources & verification
Last verified August 2026. Cost figures are modeled estimates based on national baselines adjusted for local labor and material pricing — they are not quotes. Permit rules change; confirm with the building department before starting work.
Page data quality: 100/100
- ✓ Verified permit status
- ✓ Official source linked
- ✓ Local cost range
- ✓ Inspection detail
- ✓ Unique local rule
- ✓ Local fee estimate
- ✓ Useful FAQ
- ✓ Relevant calculator
- ✓ Internal links