SANTA CRUZ COUNTY ACCESSORY DWELLING UNIT DESIGN BOOK · 2 | Santa Cruz County ADU Design Book DRAFT 9/11/2017 TABLE OF CONTENTS 1 DECIDING TO BUILD AN ADU?1 How-To Guide 2 Feasibility

NOTE: Document is a sample of the final product and not yet complete.

ACCESSORY DWELLING UNIT

DESIGN BOOKSEPTEMBER 2017

SANTA CRUZ COUNTY

2 | Santa Cruz County ADU Design BookDRAFT 9/11/2017

TABLE OF CONTENTS

1 DECIDING TO BUILD AN ADU? 1How-To Guide 2Feasibility Flow Chart 3Minimizing Cost of Your ADUs 4Frequently Asked Questions (FAQ) 6

2 DESIGN YOUR ADU 9ADUs inside the Urban Service Line 10ADUs outside the Urban Service Line 13Standard Conversion 16Remodeled Single Family Home 17

1

DRAFT 9/11/2017Deciding to Build an ADU | 1

The County of Santa Cruz is encouraging the creation of more Accessory

Dwelling Units, or ADUs. As you may know, an ADU, also known as an

“accessory unit”, “second unit”, “in-law-unit”, or “granny flat”, is an

additional smaller unit on the same property as an existing single-family

home. ADUs add housing to our community without the need to subdivide

the land to create new parcels.

ADUs can take make forms, including new detached units, additions to

an existing home or garage, or the conversion of existing space to a new

habitable unit. Regardless of the form, a homeowner must work through

several steps in order to legally create a ADU on his or her property.

This Design Book walks homeowners through the process of building an

accessory dwelling unit, from pre-application through occupancy. It also

offers guidance on the many configurations and design options that are

available to homeowners, in an effort to assist homeowners in finding the

best design for their property and for the future occupants of their ADU.

Users of this Design Book should simultaneously consult the Santa Cruz

County ADU Financing Guide, which discusses the various costs and fees

associated with building an ADU as well as the various methods available

to homeowners for financing the construction of an ADU.

1 DECIDING TO BUILD AN ADU?

KNOW BEFORE YOU GO!• The How-to-Guide

shows every step of the process.

• The Feasibility Flowchart on the next page shows what you can build.

• Cost-minimizing tips (pages 4-5) and FAQs (pages 6-7) provide additional information.


This section is your reference for the process of building an ADU. Follow the How-To

Guide to from start to finish; work through the Feasibility Flowchart to determine the

allowable size of your ADU; see tips for minimizing the cost of your ADU; and review the

FAQs.

How-To Guide

Contact the Zoning Counter to Confirm Eligibility and Allowed Size of ADU• Work through Feasibility Flowchart on the following page

• Contact the permit counter to discuss options as well as any compounding

factors (steep slopes, double frontages, Agriculture setbacks, existing

accessory structures, septic systems, etc.) that could require additional work.

• Consult the Financing Guide for ballpark costs.

Design and Preparation• NewConstructionorConversion?Refer to Chapter 3 for guidance and

inspiration. Get a free estimate at the permit counter..

• Consideryouroptionsfordraftingplans.Hire a designer or architect? Draw

your own plans? Purchase plans? Purchase a manufactured unit? Purchase a

pre-fab unit?

• Consideryouroptionsforbuilding. Hire a contractor? Construct the unit

yourself?

• Once you select an ADU option, obtain a list of plan submittal requirements.

Submit Plans for Building PermitExpect 2 to 3 rounds of comments/re-submittals.

Record Deed RestrictionOwner occupancy of the parcel is required.

Obtain Permits and Pay Fees• Obtain your building permit and any other necessary permits.

• Pay all fees as required.

Construct Your ADUComplete all Required Performance Inspections.

Occupy your ADU!Review the How to Be a Landlord guide, accepting housing vouchers, etc.

Pre-

app

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ion

Phas

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esig

n Ph

ase

Perm

ittin

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hase

Con

stru

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O

ccup

ancy

DETERMINE WHETHER YOUR PROPERTY IS...

IS THERE ONLY ONE SINGLE-FAMILY DWELLING ON YOUR PROPERTY?

OKAY, NOW DETERMINE...

PROPERTY SIZE

IF YOUR PROPERTY IS INSIDE OR OUTSIDE THE URBAN SERVICES LINE (USL)

FROM THAT INFORMATION, FIND THE ALLOWABLE ADU GROSS FLOOR AREA FOR YOUR PROPERTY

ZONED RESIDENTIAL

INSIDE USLPROPERTY SIZE

OUTSIDE USL

DESIGNATED RESIDENTIAL

BY THE GENERAL

PLAN

LOCATED OUTSIDE OF

COASTAL ZONE AND

ZONED AGRICULTURE

ANYTHING ELSE

FOR MORE DETAILS:

YES No

Less than 5,000 SQ. FT.

10% of parcel50% of primary

dwelling or 640 SQ. FT., whichever is less

50% of primary dwelling or 640 SQ. FT., whichever is less

5,000 to 9,999 SQ. FT.

640 SQ. FT. 800 SQ. FT.

800 SQ. FT.

640 SQ. FT. 800 SQ. FT.

800 SQ. FT. 1,000 SQ. FT.800 SQ. FT. 1,000 SQ. FT.

800 SQ. FT. 1,200 SQ. FT.800 SQ. FT. 1,200 SQ. FT.

10,000 SQ. FT. to 1 acre

Greater than 1 acre

NEW CONSTRUCTION NEW CONSTRUCTIONCONVERSION CONVERSION

EXPLORE OTHER DEVELOPMENT OPTIONS THAT COULD MEET YOUR NEEDS

SEE PAGES 10-12 SEE PAGE 16 SEE PAGES 13-15 SEE PAGE 16

1 2

3

NEW CONSTRUCTIONBuilding a new structure or adding on to an existing structure.

CONVERSIONConverting part of a legally constructed existing home, garage, barn or other accessory structure.


www.sccoplanning.com/PlanningHome/zoningDevelopment/What’sMyZoning.aspx

Feasibility Flowchart


There are many alternatives for an ADU to building the typically envisioned “back

yard cottage,” which entails the most expensive type of construction. Consider

all the options that could meet your housing needs before settling on a style of

construction and location for your ADU.

Consider whether a remodel to your existing single family home would meet your needs. Remodels could be substantially cheaper than construction of a full,

independent dwelling unit.

» A limited area for food prep that does not include a full stove or oven, as

well as a new exterior door is allowed as a remodel to an existing home.

Consider a conversion ADU.If there is existing habitable space in your home or an outbuilding that would be

suitable for a Conversion ADU, both construction and permitting costs could be

substantially reduced. In order to be a fully legal Accessory Dwelling Unit, the

space must have a full bathroom, full kitchen, separate entrance, separate heat

source, and sound and fire-wall separation from the primary home.

Consider converting an existing garage.Do you have space to relocate the existing parking spaces? These can be

replaced as uncovered parking in tandem or triple tandem on your lot.

» You may want to consult with a contractor regarding

the condition and quality of the existing structure to

see if converting is financially more feasible.

Consider an addition to an existing structure.Additions to existing homes, depending on the age of the existing structure,

can also be more cost effective, especially for smaller units, than new, detached

construction.

» Additions under 500 sf are exempted from certain permit reviews

and fees, creating the potential for considerable cost savings.

Minimize the Cost of Your ADU

Refer to the ADU Financing Guide for additional information on septic system upgrades.


Explore various site-planning techniques.Once you’ve settled on a style of construction, consider site planning to minimize

costs:

» Inside the USL, ADUs are required to be no more than 100 feet

from the primary dwelling and must use the same driveway (though

a driveway is not required to extend all the way to the ADU).

» If you use a septic system, consider its location and elevation relative

to a new ADU, and what additional costs this could create.

» ADUs created as New Construction entail a parking requirement, at a rate

of 1 parking space per bedroom, which must be accommodated on site.

Consider pre-fab homes.If detached new construction is the style of ADU that works best for your needs,

consider whether a manufactured home or a prefab home would work on your

site. Factory-built housing is legal to use as an ADU so long as it is attached to

all required utilities and permanently mounted to an appropriate foundation on

the site. These units can represent significant construction cost savings in many

locations.

» See list of Resources.


What permissions do I need in order to begin building? Once you have determined what you want to build, your project will require

a building permit. It may also require additional permits related to grading or

septic upgrade. If you are designing an ADU that exceeds any of the site or

dimensional standards, you may also need to go through a discretionary design

review process.

Is there any limit on the number of ADUs that can be built in the County, or in my neighborhood each year?No. There are no limits on the number of permits that can be issued for ADUs

in the unincorporated County. Typical years have seen between 15 and 35

new ADUs created, and the County expects these numbers to increase in the

foreseeable future.

How do I start the permit process?Consult the How-To Guide on page 2. Once you’re ready to contact the Zoning

Counter, you may either visit in person at any time from 8:00 a.m. to noon

and 1:00 p.m. to 3:00 p. m.. You may also call the General Information Desk at

(831) 454-3252 with questions, or find more information online at http://www.

sccoplanning.com/PlanningHome/BuildingSafety/PermitTypes.aspx.

Do I need to go through a public hearing process, or go to my neighbors and inform them of my plans for an ADU? No. As long as the plans for your ADU satisfy the standards set in the ordinance

and you can get your building permit, you do not need to go through an additional

discretionary hearing process. However, if your design:

» Exceeds the height standard by up to five feet, you will need to pursue

a Design Review permit for extra height (only up to 5 feet is allowable).

This process will involve a site visit by staff to ensure that an over-height

building will not create excessive impacts on neighboring properties

or on public Coastal views (if property is inside the Coastal Zone). The

findings of the review will be formalized in a public hearing before the

Zoning Administrator. See Code Section 13.10.323(E)6(g) for more detail.

» Relies upon reduced setbacks for a new garage, you may show a

setback reduction of up to 50% without the need for a special permit.

For residential lots less than 10,000 sf in size, the setback may be

reduced to zero with an administrative site development permit

(Level IV). Details apply, see County Code Section 13.10.323(E)6(f).

» Does not conform to any other site or structural

standard, you may require a variance or minor exception.

See Code Sections 13.10.230 and 13.10.235.

FAQs

The Santa Cruz County ADU Financing Guide provides additional detailed information on:

• Cost estimation

• Property taxes

• Fees

• Septic system considerations

• Renting your ADU and being a landlord


How much will this cost me?Refer to the Santa Cruz County Accessory Dwelling Unit Financing Guide for

estimates of construction costs as well as potential financing options.

How will the ADU affect my property tax bill?Refer to the Financing Guide.

My property is on septic. Can I still build an ADU?An ADU is an allowed use on your property, regardless of size or septic status.

However, the technical requirements for septic systems may be challenging

or expensive to meet on small parcels with older systems. The Environmental

Health Department can help you understand the requirements of your systems,

and provide advice about evaluating your existing system. Check in with them

early in the process.

What are the requirements and associated fees of my water purveyor/sanitation district/fire district? (e.g., Soquel Creek, Water District, San Lorenzo Valley Water District, Central Fire, etc.). Will I be able to build an ADU?While an ADU is a permitted use on your residential property, there are

mitigating circumstances that may make construction substantially more

expensive in certain neighborhoods. Once you know your special districts, we

recommend contacting them directly to discuss the requirements and costs

of building or legalizing an ADU on your parcel. Follow the instructions on the

“What’s My Zoning?” web page, to get to the County GIS system. The “Special

Districts” tab will tell you your water, fire, sanitation, and flood control district

where applicable. The Zoning Counter can also help you access this information.

There is an accessory structure on my property that was not constructed with permits. Can I convert it into an ADU?Maybe. Your first step will be to visit the zoning counter and find out what

standards could be applied to the construction of the structure as well as its

location on your parcel. There is no risk in asking these questions, as the County

Code enforcement process operates solely on a complaint basis unless there is

an imminent risk to health and safety.

Do I need to install fire sprinklers in my ADU?Fire sprinklers are only required in an ADU if they are already present or are

being installed in the primary home on the parcel. You will still need a sign off

from the appropriate fire district, and will need to comply with the Fire Code

generally, and there may be circumstances in which installing sprinklers is the

most cost effective option for meeting the requirements of the Fire Code.


Do I need to live on the property?Yes. At the time of application for a new or legalized ADU, the County will confirm

that you are claiming a Homeowner’s Tax exemption or can otherwise prove the

property is your primary residence.

I would like to rent out my ADU as long-term housing. What do I need to do to become a landlord?The Financing Guide contains a list of resources that will help you explore your

legal responsibilities to a paying tenant.

Can I rent out my ADU as a vacation rental on a short term basis?No. An ADU can not be used as a short term rental or vacation rental. If you wish

to operate a Vacation Rental on your property, you will need to obtain a Vacation

Rental Permit for the primary dwelling on your parcel. Then you can either

occupy the ADU as your primary residence and rent the primary dwelling as a

Vacation Rental, or operate the Vacation Rental while you are away from your

home. County Code Section 13.10.694 governs Vacation Rental uses.

Can I build two ADUs?No; only one ADU is permitted per qualified parcel. Depending on your zoning

and parcel size there may be other options for you to create additional living

space on your parcel. Consult with the Zoning Counter to explore your options.

2

DRAFT 9/11/2017Design Your ADU | 9

This chapter provides summary diagrams of development standards;

sample floor plans; considerations, tips and best practices; and example

photos of the following ADU types:

• ADUs within the Urban Service Line

» Detached New Construction (p.10).

» New Construction above a Detached Garage (p.11).

» Attached New Construction (p.12).

• ADUs outside of the Urban Service Line

» Detached New Construction (p.13).

» New Construction above a Detached Garage (p.14).

» Attached New Construction (p.15).

• Standard Conversions (p.16).

In addition, page 17 of this chapter shows examples of and design ideas for

remodels of single-family homes. This option does not create a separate,

ADU; rather, it is a way for homeowners to improve and/or create

“rentable” space from existing interior space.

Insert reference to relevant zoning code sections.

To determine whether your property is within or outside of the Urban Service Line, go to:www.sccoplanning.com/PlanningHome/zoningDevelopment/What’sMyZoning.aspx

2 DESIGN YOUR ADU

Rear property line

Front property line

Max. 1 story and 640 sq. ft.

Max.17 ft.

Avg.14 ft.

Setbacks same as zone district standards

DEVELOPMENT STANDARDS

EXAMPLES AND BEST PRACTICES

SAMPLE FLOOR PLANS


Approx. 640 sq. ft. detached ADU.

Includes one bedroom and full

kitchen.

Approx. 360 sq. ft. detached

ADU. Includes studio

bedroom/living area and full

kitchen.

• Even on a lots less than

5,000 sq. ft., an ADU is

possible without exceeding

the 0.5 FAR and 40%

lot coverage limitations.

Limiting factors will

generally be:

» Required building

separation

» Required off-

street parking

• Separate average and

maximum height limits

encourage interesting roof

forms: This diagram illustrates:

• Zone district: R-1

• Lot: 6,600 sq. ft. (60’ x 110’)

• Primary dwelling: 950 sq. ft.

• ADU: Max. 640 sq. ft.

• Innovative interior design

can accommodate full

kitchens in small spaces.

www.accessorydwellings.org

www.urbanland.uli.org


Detached New Construction Inside the Urban Service Line

Rear property line

Front property line

Max. 2 stories and 640 sq. ft.

Max.24 ft.

Avg.21 ft.

Minimum setbacks: Sides: 5 ft. Rear: 5 ft.


SAMPLE FLOOR PLANS


Design Your ADU | 11DRAFT 9/11/2017

This diagram illustrates:


• Lot: 6,600 sq. ft. (60’ x 110’)



Approx. 640 sq. ft. ADU

above existing detached

garage. Includes two

bedrooms and full kitchen.

Approx. 460 sq.

ft. ADU above

existing detached

garage. Includes

one bedroom and

full kitchen.

• Required side and rear

setbacks for an ADU above

an existing detached

garage are 5 feet,

regardless of the setbacks

of the existing detached

garage.

• An ADU above an existing

garage should be designed

with colors, materials, and

forms that are consistent

with the design of the

garage below.

• Separate average and

maximum height limits

encourage interesting roof

forms.

• Second-story window

placement should be

sensitive to the privacy of

both the ADU and adjacent

neighbors.

www.pinterest.com

www.historicshed.com

New Construction above a Detached Garage Inside the Urban Service Line

Max. 28 ft.Rear property line

Front property line

Max. 2 storiesand 640 sq. ft.

Max. 28 ft.Rear property line

Front property line

Max. 2 stories and 640 sq. ft.(320 sq. ft. footprint shown)





SAMPLE FLOOR PLANS


• Attached new construction

includes:

» a second story addition

above existing single-

family dwelling;

» a second-story

addition above existing

attached garage;

» a one-story extension

of the existing

floorplan; and

» a two-story

extension of the

existing floorplan.



• Lot: 6,600 sq. ft. (60’ x 110’)



Approx. 550 sq. ft. ADU above

existing attached garage. Includes

studio bedroom/living area and full

kitchen.

Approx. 800 sq. ft. ADU added on to

rear of single-family dwelling. Includes

one bedroom and full kitchen.

• On small lots, attached

new construction

may be more feasible

than detached new

construction.

• Placement of fixtures

to allow easy access to

existing drains and vents

can simplify an addition.

Dyett&Bhatia


www.pinterest.com

Attached New Construction Inside the Urban Service Line

Rear property line

Front property line


Max. 28 ft.




SAMPLE FLOOR PLANS




• Lot: 6,600 sq. ft. (60’ x 110’)

• Primary dwelling: 1,760 sq. ft.

• ADU: 800 sq. ft.

• A 28-foot height limit

outside of the Urban

Service Line allows two-

story ADUs. Compact

stair design may maximize

usable interior space.

(Left) Approx. 540 sq. ft. detached

new two-story ADU. Includes one

bedroom and full kitchen.

(Below) Approx. 1,200 sq. ft.

detached new two-story ADU.

Includes two to three bedrooms

and two full baths, and full kitchen.

• Location on the lot and

placement of second-

story windows should be



neighbors.

• A safe path of travel must

be provided between the

ADU and the sidewalk/

street.



www.smallhousebliss.com

Detached New Construction Outside of the Urban Service Line



DEVELOPMENT STANDARDS WHERE GARAGE & ADU ARE WITHIN STANDARD SETBACKS

These diagrams illustrate:


• Lot: 8,800 sq. ft. (80’ x 110’)


• ADU: 800 sq. ft.

DEVELOPMENT STANDARDS WHERE GARAGE & ADU SET-BACKS ARE REDUCED

New Construction above a Detached Garage Outside of the Urban Service Line

Rear property line

Front property line

Max. 2 stories and 800 sq. ft.

Max. 28 ft.


Rear property line

Front property line

Garage setbacks: Side: 5 ft.

Rear: 7.5 ft. (50% reduction, (Level IV approval required)

Max. 2 stories and 800 sq. ft. Minimum setbacks:

Sides: 5 ft. Rear 5 ft.

Max.24 ft.

Avg.21 ft.

SEE PAGE 11 FOR SAMPLE FLOORPLANS

• Outside of the Urban

Service Line, permitted

height and required side

and rear setbacks of an

ADU above an existing

detached garage depend

on the placement of the

detached garage.

• An ADU above an existing

garage should be designed

with colors, materials, and

forms that are consistent

with the design of the

garage below.

• Second-story window

placement should be



neighbors.

• Exterior stairs, windows,

and decks can enhance

the design of an ADU and

maximize efficiency of

indoor space.

www.inhabitat.com

www.houzz.com





• Lot: 8,800 sq. ft. (80’ x 110’)


• ADU: 800 sq. ft.

Approx. 1,000 sq. ft.

two-story ADU added on

to existing single-family

dwelling. Includes two

bedrooms, deck, and full

kitchen.


SAMPLE FLOOR PLAN

Attached New Construction Outside of the Urban Service Line

Rear property line

Front property line


Max. 28 ft.


• Attached new construction

includes:

» a second story addition

above existing single-

family dwelling;

» a second-story

addition above existing

attached garage;

» a one-story extension

of the existing

floorplan; and

» a two-story

extension of the

existing floorplan.

• Locating living areas

and bedrooms against

the exterior wall takes

advantage of natural light

and ventilation.

www.urbanland.uli.org

Dyett&Bhatia

www.buildinganadu.com

www.homedit.com

www.shelter-solutions.net

www.pinterest.com



SAMPLE FLOOR PLANS


• Standard conversions are

the conversion of existing

interior living space, an

existing attached garage,

or an existing detached

garage into an ADU.

• Conversion ADUs must

have full kitchens and

separate entrances to the

exterior.

• Low ceiling height of

an existing garage or

basement may require

floor excavation for the

ADU to meet Building

Code.

• The permitted”pop-out”

square footage may be

useful for new kitchen

areas, new interior

stairways that access

second-floor space, or new

covered entryways.



• Lot: 4,480 sq. ft. (56’ x 80’)


• ADU: 640 sq. ft. plus a 90 sq. ft. pop-out

(2% lot coverage and FAR)

Conversion of existing attached

garage into an approx. 530 sq. ft.

ADU. Includes studio bedroom/

living area and full kitchen.

Conversion of existing interior space into

an approx. 750 sq. ft. ADU. Includes one

bedroom, living/dining area, a full kitchen,

and an approx. 50 sq. ft. “pop-out”.

Up to 150 sq. ft. or 30% of converted area (whichever is less) pop-out permitted; Maximum overall 42% lot coverage and 0.52 : 1 FAR

Separate exterior entrance required



• Lot: 4,480 sq. ft. (56’ x 80’)


• ADU: 640 sq. ft. plus a 90 sq. ft. pop-

out (2% FAR)

Standard Conversion

DESIGN EXAMPLES


This option refers to changes to existing interior space that improves the existing structure and/or creates

more usable space but that does not create a fully separate unit. Remodeled areas may include basements,

attics, lofts, master bedrooms, mudrooms, sunrooms, or other existing interior spaces. Limited food

preparation amenities are permitted in a remodeled space.

www.homedit.com

www.accessorydwellings.org www.patch.com

Attics may be remodeled

to create additional living

space that is full-height or

partial height.

Food preparation amenities

in remodels are limited to

kitchenettes, which allow a

maximum 120 volt electrical

service, sink, and refrigerator.

(one kitchenette permitted per

parcel).

Other spaces for

remodels include

master bedroom

suites, lofts, or

sunrooms.

www.houzz.com www.pinterest.com www.decoist.com

Basement

remodels may

provide additional

living and/or

working space.

www.apartmenttherapy.com www.decoist.com

www.tinyhousedesign.comwww.homedit.com

Remodeled Single-Family Home (Not a Separate Unit)

SANTA CRUZ COUNTY ACCESSORY DWELLING UNIT DESIGN BOOK · 2 | Santa Cruz County ADU Design Book DRAFT 9/11/2017 TABLE OF CONTENTS 1 DECIDING TO BUILD AN ADU?1 How-To Guide 2 Feasibility

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