Second-Story Additions in Coronado

A small city with its own playbook

Coronado incorporated on December 11, 1890, two years after the Hotel del Coronado was built. It had 20,192 residents and 9,573 housing units in 2020, with about half of occupied homes owner-occupied. Naval Air Station North Island began as Glenn Curtiss's flying school in 1911, and the Navy is still the largest employer. The Silver Strand ties the island to the mainland, the Coronado Cays to the south were built largely on fill dredged from the bay, and the bridge to San Diego opened in 1969.

Instead of one flat floor area ratio, the single-family code uses a long table of floor area ratios and a list of design features that move a project up or down that table.

R-1A standards

From Chapter 86.08 of the Coronado Municipal Code:

Narrower lots get lower pitched-roof heights, stepping from 26 ft on lots under 27 ft wide up to 30 ft. Side facades on every story must include design relief (86.08.140).

Working the floor area table

The FAR in CMC 86.08.035 is read from a table by gross lot area, with a base and a maximum. A few points along it:

• 5,000 sq ft lot: base 0.546, maximum 0.649
• 7,000 sq ft lot: base 0.475 (3,325 sq ft), maximum 0.595 (4,165 sq ft)
• 10,000 sq ft lot: base 0.368, maximum 0.514
• 10,500 sq ft and up: base 0.350, maximum 0.500

Moving from base toward maximum takes listed features. Design Review Commission approval adds 0.04, a historic alteration permit adds 0.02, and plans stamped by an architect add 0.01. A one-story main building within 14 ft (flat) or 20 ft (ridge) adds 0.03. Some features subtract, but never below the base.

Picture a 7,000 sq ft lot, 50 ft by 140 ft, with a 1,700 sq ft one-story house and a 400 sq ft attached garage. At base FAR the lot allows 3,325 sq ft, so roughly 1,200 sq ft remains, and Design Review Commission approval alone would add 280 sq ft more. The second floor could be up to 2,100 sq ft by the first-floor rule, so the FAR is the tighter limit here. The rear setback is what reshapes the plan: 40% of 140 ft is 56 ft, so the upper floor has to stay toward the street side of the house. Confirm how garages and other areas count under the city's definitions before you lock a number.

Coastal permits and historic review

Coronado's coastal permit chapter (CMC 86.70) splits the city into areas under sole city authority, areas under city authority but appealable to the Coastal Commission, and areas outside city authority, such as federal military land and Port property. A coastal permit is required for development in city areas unless an exemption applies, and improvements to existing single-family homes are exempt when they follow the Local Coastal Program. The Director of Community Development acts as the coastal permit administrator. Ask which area your parcel is in.

Age matters too. When a project removes or demolishes original street-visible features on a structure 75 years or older that is not listed as Tier 3 in the city's historic inventory, it goes through a Determination of Historic Significance review. Any exterior change to a designated historic resource needs a Historic Resource Alteration Permit, with Historic Resource Commission findings based on the Secretary of the Interior's Standards. Designated homes in residential zones can apply for a Mills Act contract that lowers property taxes.

Plan review and fees

The Building Division at 1825 Strand Way requires plan check for additions. Handout 302 (March 2025) asks for three sets of professionally drawn 24 by 36 plans and two sets of calculations and Title 24 documents, with a storm water assessment form. Smaller projects, which the city groups with single-story additions and garages, get internal review by Building and Planning, with first comments in ten to twelve business days. Larger projects may also go to the city's plan review consultant. A courtesy notice to neighbors (handout 111) may be required, and a plan check application expires after 180 days.

Coronado publishes flat plan check and inspection fees by addition size. Under Resolution 2026-13R for fiscal 2026-27, a 500 sq ft single-family addition is $820 plan check and $1,200 inspection, an 875 sq ft addition is $1,977 and $3,206, and a 1,250 sq ft addition is $2,256 and $3,881. Swap those in for the City of San Diego fee lines in our cost calculator, whose construction lines still apply. School fees go to Coronado Unified; the state's maximum residential rate rose to $5.38 per sq ft in January 2026, and Education Code 17620 spares additions that stay at or under 500 sq ft.