CheckPre

Santa Clarita ADU Cost & Permit Fee Calculator

A 600 sq ft ADU in Santa Clarita runs about $294,000 all in, $13,728 of it city and school fees. Price your own build, fees and rental payback.

Updated · By Niraj Kumar · 11 sources

1. The ADU

Type of ADUType of ADU
sq ft
1501,200

School fees start above 500 sq ft and impact fees at 750 sq ft.

Finish levelFinish level
sq ft

Impact fees from 750 sq ft are scaled by the ADU's size against the house.

2. Site work

ft

Distance from the house's sewer lateral to the ADU.

ft
ft
Main electrical panel upgradeMain electrical panel upgrade
%
0%25%

Architect, structural engineer, Title 24 and survey, as a share of the build. About 4% with a city pre-approved plan.

%
0%30%

3. Santa Clarita fees

$

Santa Clarita estimate.

$

Waived: under 750 sq ft (state law).

$

Charged on new detached and attached units.

$

$5.38 a sq ft on the whole unit.

4. Rent and financing

Rented asRented as
$

HUD's FY 2026 fair market rent for the metro, a conservative figure. Enter a local listing to replace it.

%
0%50%
%

Charged on the ADU's construction cost only; the house is not reassessed.

$
% of rent
0%30%
How you payHow you pay
years
5 yrs30 yrs
%

Net rent ÷ cap rate is how appraisers value income. 4-6% is typical for California rentals.

Total cost, Santa Clarita$293,826$490 a sq ft, $13,728 of it fees

At 500 sq ft it would pay no school fees, saving $3,228.

Construction
$280,098
build, site work, design and contingency
City and school fees
$13,728
Monthly cash flow, year one
$1,482
on $2,085 rent
Payback
13.5 years
6.1% cash-on-cash in year one
Value added
$355,726
$61,900 more than it costs, at a 5% cap rate
Where the money goes600 sq ft detached ADU, standard finish
  1. 1Construction$226,800
  2. 2Contingency$23,814
  3. 3Design and engineering$18,144
  4. 4Utility trenching$11,340
  5. 5Permit and plan check$8,000
  6. 6School fees$3,228
  7. 7Sewer and water capacity$2,500
Cumulative cash flow from rentStill to recoverAhead
$-300 K$-200 K$-100 K$0$100 K$200 KPayback, year 13.5048121620
Year-by-year rent and cash flowShow
YearRent collectedRunning costsLoanCash flowCumulative
1$23,769$5,983$0$17,786-$276,040
2$24,482$6,131$0$18,351-$257,689
3$25,217$6,284$0$18,933-$238,756
4$25,973$6,440$0$19,533-$219,224
5$26,752$6,601$0$20,151-$199,072
6$27,555$6,766$0$20,789-$178,283
7$28,381$6,934$0$21,447-$156,836
8$29,233$7,108$0$22,125-$134,711
9$30,110$7,286$0$22,824-$111,887
10$31,013$7,468$0$23,545-$88,342
11$31,944$7,655$0$24,288-$64,053
12$32,902$7,847$0$25,054-$38,999
13$33,889$8,045$0$25,844-$13,155
14$34,906$8,247$0$26,659$13,504
15$35,953$8,454$0$27,498$41,003
16$37,031$8,667$0$28,364$69,367
17$38,142$8,886$0$29,256$98,623
18$39,287$9,110$0$30,176$128,799
19$40,465$9,340$0$31,125$159,924
20$41,679$9,577$0$32,103$192,027

How the Santa Clarita ADU Cost & Permit Fee Calculator works

A new 600 sq ft detached ADU in Santa Clarita costs about $294,000 to build in 2026, including $13,728 in permit, capacity and school fees. Impact fees do not apply under 750 sq ft. Rented at $2,085 a month, it pays back in about 13 years.

Cost = sq ft × rate₍type, finish₎ × city index + utility runs + panel + design + contingency + fees fees = permit + impact × (ADU ÷ house, from 750 sq ft) + capacity (new builds) + school × sq ft (over 500) Payback: Σ₍y₎ (rent × (1 − vacancy) − tax − insurance − upkeep − loan) ≥ cash invested

This page uses the same method as the California ADU Cost & ROI Calculator, which explains each term and assumption in full.

Worked example

A 600 sq ft detached one-bedroom ADU at standard finish behind a 1,600 sq ft house in Santa Clarita, with utility lines run 50 ft from the house, paid in cash.

  1. 1Construction: 600 sq ft at about $378 a sq ft is $226,800; utility trenching adds $11,340, design $18,144 and a 10% contingency $23,814
  2. 2Fees: $8,000 in permit and plan check, no impact fees (under 750 sq ft), $2,500 in sewer and water capacity, and $3,228 in school fees
  3. 3Rent of $2,085 a month less 5% vacancy, property tax, insurance and upkeep leaves $17,786 a year

The ADU costs about $293,826 all in, $490 a sq ft, of which $13,728 is fees. The rent repays it in about 13.5 years, a 6.1% cash return in the first year.

Frequently asked questions

How much are ADU permit fees in Santa Clarita?

For a new 600 sq ft detached ADU, city and school fees come to about $13,728: $8,000 in permit and plan check, $2,500 in sewer and water capacity charges and $3,228 in school fees. At 800 sq ft they rise to about $21,304, including $2,500 in impact fees. Going from 749 to 750 sq ft alone adds about $6,349. A garage conversion pays a smaller permit fee and no capacity charge.

How much does it cost to build an ADU in Santa Clarita?

About $294,000 for a 600 sq ft detached ADU at standard finish, all in, or $490 a sq ft, and about $391,000 for 800 sq ft. Rented as a one-bedroom at $2,085 a month, the HUD fair market rent for the area, it would repay a cash build in about 13.5 years. A garage conversion typically costs 35-45% less.

What is unusual about ADU fees in Santa Clarita?

The Planning Division's ADU fee is $425 (2026 schedule); building, electrical, plumbing and mechanical permits bring the total to $10,000-$20,000 in builder estimates. Sewer is through the LA County Sanitation District.

Sources

Related calculators

More in Construction & DIY