Now Available: 2023-2031 Housing Element Update Adequate Sites Inventory Explorer

A key component of the Housing Element is the identification of sufficient development capacity to meet the County’s housing need over the 8 years of the Housing Element planning period (2023-2031). State law requires that every jurisdiction’s Housing Element demonstrate that the jurisdiction has sufficient appropriately zoned developable or redevelopable land to accommodate the jurisdiction’s share of regional housing need, as determined by the California Department of Housing and Community Development (HCD) and the local Council of Governments (COG).  In the Bay Area, the COG is the Association of Bay Area Governments (ABAG), which estimates housing need for the region, and apportions a share of projected need to every jurisdiction; a jurisdiction’s individual share of housing need is its Regional Housing Needs Allocation, or RHNA. The RHNA includes both total projected residential units needed to meet demand over the next 8 years, and a breakdown of housing units needed by income level. 

More detailed versions of the tables on this page are available here.

The County’s RHNA is 2,833 housing units in total, with 811 units for very low-income households, 468 for low-income households, 433 for moderate-income households, and the remainder for above moderate-income households.

San Mateo County RHNA, 2022 - 2031

Income Category

% of County Area Median Income (AMI)

Units

% of Units

Very Low

0-50%

811

29%

Low

51-80%

468

17%

Moderate

81-120%

433

15%

Above Moderate

120% +

1,121

40%

Total

 

2,833

100%

The assessment of developable and redevelopable sites, and pipeline projects already underway, can be viewed through the 2023-2031 Housing Element Update Adequate Sites Inventory Explorer, an interactive web mapping tool that allows exploration of all the sites in the Inventory, mapped and depicted with location and characteristics.  

The County’s ability to meet its RHNA over the next 8 years comes from the following sources:

  • Vacant, developable single-family residentially zoned sites
  • Vacant, multifamily residentially zoned sites
  • Non-vacant, redevelopable multifamily sites
  • Pipeline projects significantly advanced in the approval and/or development process, but not yet completed
  • Projected development of Accessory Dwelling Units
  • Projected development of units pursuant to SB 9, a new state law that allows low-density multifamily development of single-family zoned parcels

The full Adequate Sites Inventory and methodology will be presented in the draft updated Housing Element, and will include a detailed inventory and description of developable and redevelopable sites, and a description of methodology for assessing site developability, affordability, and projections of future development. 

The number of units attributable to each category is shown below.

Vacant and Non-Vacant Developable and Redevelopable Sites

Sites Inventory: Total Sites and Units by Income Category, Vacant and Non-Vacant Sites

Income Category

Vacant Single-Family Residential

Vacant Multifamily Residential

Non-Vacant Multifamily Residential

 Very Low 

0 

42 

381 

 Low 

0 

33 

144 

 Moderate 

0 

34 

214 

 Above Moderate 

676 

141 

645 

 Total Units 

676 

250 

1,384 

 Total Sites 

676

19

69
 
Recently Completed Projects

The following tables show recently completed projects, which help identify development trends, feasibility of development, and other indications of what types of development are possible on various types of sites, and pipeline projects, which are already approved, entitled, or significantly advanced in the permitting and development process, but which have not yet been completed, and which count against the County’s 2023-2031 RHNA.  

More detailed versions of the tables below, including more complete project descriptions, characteristics, and project status, are available here.

Recently Completed Multifamily Projects, Unincorporated San Mateo County

Project Location

APN

Zoning

Size (Acres)

Density (unit/acre)

Total Units

Affordable Units

North Fair Oaks

060271120

NMU-ECR

1.40

64.46

90

0

North Fair Oaks

054263150

R-3/S-5

0.29

52.00

15

9

North Fair Oaks

054284360

CMU-1

0.60

110.85

67

67

North Fair Oaks

060265150

PUD-137

0.41

38.77

16

16

Colma

081411100

PC

0.98

32.80

32

0

El Granada

047206230

R-3/S-3

0.39

30.64

12

1

Redwood City

069261440

R-3/S-3

0.33

33.48

11

1

El Granada

047271200

R-3/S-3

0.25

36.61

9

1
 

Pipeline Projects

APN

Community

Very Low Income

Low Income

Moderate Income

Above Moderate Income

Total Units

054113140

North Fair Oaks

        103 

          76 

            -   

            -   

179

037097200

Moss Beach

          -   

            1 

            -   

             7 

8

060041080

North Fair Oaks

          59 

          20 

             1 

            -   

79

054284220

North Fair Oaks

          -   

            1 

            -   

             8 

9

060083360

North Fair Oaks

          -   

          -   

             1 

             6 

7

054284200

North Fair Oaks

0

0

0

4

4

037022070

Moss Beach

35

35

0

1

71

060041110

North Fair Oaks

16

17

41

95

169

060053100

North Fair Oaks

42

43

0

0

85

054232090

North Fair Oaks

49

49

1

1

99

069341050

Redwood City

0

3

0

20

23

069311350

Redwood City

0

1

0

5

6

 

Totals:

303

246

44

147

739
 
Recent ADU Development

The County has amended its ADU regulations multiple times, beginning in 2017, to streamline and facilitate production of ADUs. The past several years show significant increase in ADU production since amendment of the regulations.

Recent ADU Production by Year

Year

ADUs

2012

8

2013

6

2014

13

2015

6

2016

10

2017

14

2018

31

2019

34

2020

31

2021

43

Total

196
 
Projected ADU Development

Based on recent development trends, ADUs production is predicted to continue to increase modestly across the 8-year Planning Period. The affordability assumptions for ADUs, shown in the RHNA vs Development Capacity Table below, are based on actual market research by ABAG and the University of California, Berkeley. 

Projected ADUs, Housing Element Period

Year

Projected ADUs

2023

35

2024

35

2025

40

2026

40

2027

45

2028

50

2029

55

2030

55

Total

355
 
Project SB 9 Development

SB 9, a new state law effective as of January 2022, allows the development of up to four units on parcels normally zoned to allow no more than one single-family unit. In the first six months after the law took effect, the County received 12 SB 9 applications that would result in 18 net new units. However, projections of SB 9 development over the Planning Period.

Note that these projections are significantly below maximum potential SB 9 development, based on capacity of eligible sites. The County’s assessment of potentially eligible SB 9 parcels can be seen here.

Projected Units Developed Through SB 9, Housing Element Period

Year

Applications

Net New Units

2023

10

12

2024

12

14

2025

14

21

2026

16

24

2027

16

24

2028

16

24

2029

18

27

2030

20

30

Total

122

176
 
RHNA vs Development Capacity

The combination of these categories, shown below, demonstrates that the County has sufficient capacity to meet its 2022-2031 RHNA, in total and by income level.

RHNA vs Development Capacity

Income 

RHNA

Vacant SFR

Vacant MFR

Non-Vacant 

Pipeline

ADUs

SB 9 

Total 

Surplus

 Very Low 

811 

0 

42 

381 

303 

107 

0 

834 

23 

 Low 

468 

0 

33 

144 

246 

107 

0 

528 

60 

 Moderate 

433 

0 

34 

214

44 

107 

88 

482 

54 

 Above Moderate 

1,121 

676 

141 

645 

147 

36 

88 

1,732 

611 

 Total 

2,833 

676 

250 

1,384 

740 

355 

176 

3,581 

748