800 sq ft ADU · checked Oct 18, 2026
800 sq ft ADU fees in Redwood City: $9,458, $258 more than at 750 sq ft
Redwood City charges no impact fees that we model, so going from 750 to 800 sq ft adds only $258 in size-based fees such as school fees and permits.
750 vs 800
What the extra 50 sq ft changes in Redwood City
- School impact fee (Sequoia Union High School District): $3,878 at 750 sq ft → $4,136 at 800 sq ft
Staying at 750 sq ft would save about $258 in fees under today’s law.
Line by line: 750 sq ft vs 800 sq ft, now and under SB 1117
Detached ADU, 2,000 sq ft main home (example assumption). The 2027 column applies SB 1117, which limits impact fees to the area over 750 sq ft.
| Fee | 750 sq ft (2026) | 800 sq ft (2026) | 800 sq ft (from 2027) |
|---|---|---|---|
| Building permit & plan check | |||
| New ADU base building fee (City estimate) | Est.$5,322 | Est.$5,322 | Est.$5,322 |
| Impact fees | |||
| Park impact fee (ADUs exempt until April 1, 2027) | Exempt | $0 | $0 |
| Transportation impact fee (ADU: $0) | Exempt | $0 | $0 |
| School district fee | |||
| School impact fee (Sequoia Union High School District) | $3,878 | $4,136 | $4,136 |
| Modeled total | $9,199 | $9,458 | $9,458 |
State law
Why 800 sq ft is the size every city must allow
Local limits on lot coverage, floor area ratio, open space and minimum lot size can’t stop an 800 sq ft ADU with 4 ft side and rear setbacks, and a detached unit of up to 800 sq ft must be approved ministerially alongside a junior ADU.
Redwood City: Up to 850 sq ft for a one-bedroom ADU, or 1,000 sq ft with more than one bedroom.
Gov. Code §66321(b)(3)
size based upon a percentage of the proposed or existing primary dwelling, or limits on lot coverage, floor area ratio, open space, front setbacks, and minimum lot size, for either attached or detached dwellings that does not permit an accessory dwelling unit with at least 800 square feet of interior livable space and with four-foot side and rear yard setbacks to be constructed in compliance with all other local development standards.
Gov. Code §66323(a)(2)
One detached, new construction, accessory dwelling unit that does not exceed four-foot side and rear yard setbacks for a lot with a proposed or existing single-family dwelling.
Gov. Code §66323(a)(2)(A)
A total floor area limitation of not more than 800 square feet of livable space.
Quoted from Government Code, Title 7, Division 1, Chapter 13 (Accessory Dwelling Units), incl. §66311.5 (opens in new tab), checked Oct 18, 2026.
FAQ
Questions about 800 sq ft adu in Redwood City
How much are the fees for an 800 sq ft ADU in Redwood City?
Our model of Redwood City’s official schedules comes to $9,458 for a detached 800 sq ft ADU with a 2,000 sq ft main home, compared with $9,199 at 750 sq ft.
Does an 800 sq ft ADU pay impact fees in Redwood City?
No impact fees that we model. State law would allow proportional impact fees above 750 sq ft, but Redwood City’s schedules we use don’t charge any for this ADU.
Can Redwood City stop me from building an 800 sq ft ADU?
Not with lot coverage, floor area ratio, open space or minimum lot size limits. State law requires cities to allow at least an 800 sq ft ADU with 4 ft side and rear setbacks (Gov. Code §66321(b)(3)), provided it meets other objective standards such as height.
Do school fees apply at 800 sq ft?
Yes. School fees apply above 500 sq ft; at 800 sq ft the statewide Level 1 cap is $4,304, and many districts charge less.
Not modeled yet
What these totals leave out
- The City's base-fee estimate stops at 800 sq ft, so larger ADUs show as not modeled for that line.
- Valuation-based, administrative and maintenance fees and the water and sewer capacity fees (which the City says apply to ADUs) are in the Master Fee Schedule and aren't modeled yet.
- A fire flow test is required for new detached ADUs; its fee isn't included.
- Local height and parking rules not captured yet; the state minimums apply.
More
Keep going
Sources
Official sources
Every figure comes from these documents; each line’s quoted text is on the Redwood City page.
- City of Redwood CityAccessory Dwelling Unit Ordinance (ADU information page) (opens in new tab)
- City of Redwood City, Parks, Recreation and Community ServicesPark Impact Fees (2026) (opens in new tab)
- City of Redwood City, Community Development DepartmentDevelopment Impact Fees (updated July 2026) (opens in new tab)
- California Legislative Information (leginfo.legislature.ca.gov)Government Code, Title 7, Division 1, Chapter 13 (Accessory Dwelling Units), incl. §66311.5 (opens in new tab)
- HCD via data.ca.govHousing Element Annual Progress Report (APR) data, Table A2: ADU building permits by year (opens in new tab)