Building a guest house can be a great way to increase your property’s value or provide additional living space for family and guests. Whether you’re considering a small one bedroom unit or a large 1200 square foot space, understanding the costs, design options, and regulations involved is essential. This guide will walk you through everything you need to know about planning, financing, and constructing a guest house in your backyard.
What Is a Guest House?
A guest house is a secondary living space on a property that provides accommodation for guests, family members, or tenants. They are primarily detached, standalone units, but they can also be attached to the primary home or a conversion of existing space such as a garage.
What Is the Difference Between a Guest House and an ADU?
Many people use the terms “guest house” and “Accessory Dwelling Unit (ADU)” interchangeably. Many times someone will refer to an ADU as a guest house when the unit is used as a flexible space for overnight guests, a home office, a pool house, etc. However, many cities around San Diego have separate regulations for a term called “guest quarters”, which are completely different.
What Is the Difference Between a Guest House and Guest Quarters?
Guest quarters differ from guest houses and ADUs, and definitions vary by jurisdiction. For example, San Diego County says that guest living quarters cannot include full kitchens, laundry facilities, or wet bars and are restricted to temporary use. The County also prohibits having both guest living quarters and an ADU or junior ADU (JADU).
In contrast, the City of San Diego allows guest quarters in addition to ADUs and JADUs. Guest quarters in the city may include a bar sink and mini-fridge but cannot have full kitchen facilities.
Some jurisdictions do not allow guest quarters at all or have mention of them in their code, and some jurisdiction such as Encinitas and Carlsbad refer to “guest quarters” as a “guest house”. Understanding your local rules is crucial to ensuring your ADU and/or guest quarters project complies with local regulations.
TABLE: Guest Quarters Regulations By City
 County of San Diego |
Guest quarters are NOTÂ allowed on properties with existing ADUs, JADUs, accessory apartments, or accessory living quarters. Guest quarters stays are restricted to a maximum of 30 days per calendar year, and they cannot include kitchens, wet bars, or laundry facilities. These units must not function as separate dwellings or be rented out. Size restrictions dictate that guest quarters cannot exceed 30% of the main home’s square footage, with a maximum of 600 square feet. Additional space up to 50% of the main home’s size may be granted through an Administrative Permit. Only one electric meter is allowed for both the main home and guest quarters. They are permitted in specific zoning areas (A70, A72, RR, RS, RV, RU, RRO, S88, S90, and S92). In RS, RV, RU, RRO, and S88 zones, the lot must be at least 20,000 square feet unless an Administrative Permit is obtained. |
City of San Diego |
Guest quarters are allowed in addition to ADUs and JADUs. Guest quarters cannot be rented, leased, or sold as separate dwelling units. They must be used only by occupants of the primary dwelling, their guests, or their employees. Kitchens or food preparation facilities are not allowed, though a bar sink and mini fridge may be permitted. Size limitations restrict guest quarters to a maximum of 25% of the allowable gross floor area of the premises. Their square footage is included in the floor area ratio calculation for the property. |
Encinitas |
Guest quarters (referred to as guest house in Encinitas) are allowed in addition to ADUs and JADUs. In residential zones, one detached guest house is allowed per lot with a minimum area of 10,000 square feet. Guest houses are not permitted in other zones. The maximum floor area for a guest house is 640 square feet, and it must comply with the main building setbacks for the designated residential zone. Larger guest houses or those maintaining accessory structure setbacks require a minor use permit. A variance is needed for any guest house that does not meet either main building or accessory structure setback requirements. Kitchen and laundry facilities are not allowed. Guest houses can only be occupied temporarily for up to 30 consecutive days and cannot be rented or used as separate dwellings. |
 Carlsbad |
Carlsbad defines “Guest house” or “accessory living quarters” as living quarters within an accessory building for the sole use of persons employed on the premises, or for temporary use by guests of the occupants of the premises. Such quarters shall have no kitchen facilities and shall not be rented or otherwise used as a separate dwelling unit.
Per city planning as of March 2025, guest house regulations depend on the zone and the specific parcel. For example, in the R-1 zone, they are considered detached accessory structures and allowed in addition to ADUs. In this zone they are allowed to be up to 440 sf with a 20′ front yard setback and a 5′ rear yard, side yard, and alley setback. Read more about R-1 accessory structure development standards. |
 Chula Vista |
Guest quarters are only allowed in the Residential Estates (RE) zoning where they are allowed in addition to ADUs. They are defined as detached living quarters for the use of occasional guests of the occupants of the main home. There is a maximum stay of 90 days and the space may not be rented or leased out. No kitchen or cooking facilities are allowed. Guest houses shall not be closer than 10 feet to the nearest point of the main building. |
Solana Beach |
Based on city feedback in February 2025, the City no longer permits guest houses or pool houses. They only permit attached or detached accessory structures (ADUs) and garages/storage sheds. |
Oceanside |
No mention of Guest Quarters in city code. |
Poway |
No mention of Guest Quarters in city code. |
Source: SnapADU & local regulations
The Benefits of Building a Guest House
Financial Benefits of a Guest House
Building a guest house can significantly increase property value. It provides additional livable square footage, which can boost resale value. If used as a rental, a guest house can generate passive income. Many properties with ADUs or guest houses sell at a premium because they offer income producing potential. Read more about renting your guest house.
Lifestyle Benefits of a Guest House
A guest house isn’t just an investment, but also a highly functional addition to your home. Some common use cases include:
- Hosting guests – Provide comfortable accommodations for family and friends. For example, check out this Flex Space ADU in San Diego designed to be used either as additional accommodations for the homeowner’s family or as a rental.
- Multigenerational living – Give aging parents or adult children a private, independent space. Read more about multigenerational ADUs.
- Rental income – Offset mortgage costs by renting out your guest house.
- Home office or creative studio – Create a quiet workspace away from the main house.
- Pool house or entertainment area – Enhance your backyard with a stylish and practical space. Read more about poolside ADUs and take a look at this modern pool house ADU in Carlsbad for some inspiration!
Where Can I Build a Guest House?
In California, state laws allow for an 800-square-foot detached ADU on any single-family property, with a 16-foot height limitation and 4-foot setbacks from property lines. However, local regulations may permit larger units. For example, San Diego allows guest houses up to 1,200 square feet, while Poway allows up to 1,500 square feet.
Cities and counties may have additional regulations concerning setbacks, height restrictions, and whether multi-story guest houses are allowed. It’s essential to check your local zoning laws and consult with an experienced ADU builder to determine what’s possible for your property. If you are unsure as to whether you can build a guest house, we recommend checking out your city’s regulations page or reaching out to our team!
How Much Does a Guest House Cost?
Cost to Build a Guest House in San Diego
The cost of building a guest house varies greatly based on size, design, and materials as well as the property’s existing site and utility conditions. In San Diego, costs generally range from $300,000 to $500,000 or more all-in for a detached unit. The cost per square foot typically falls between $375 and $600 with construction accounting for about 80-85% of the total cost, while the remainder includes soft costs such as design, permits, and consultants and other site specific work and utilities. Read more about guest house costs.
Financing Options for Your Guest House
Financing a guest house can be done through various methods, including:
- Home equity loans – Borrow against your existing home equity.
- Cash-out refinancing – Refinance your mortgage to free up funds.
- Construction loans – Obtain a loan specifically for building expenses.
While SnapADU does not offer in-house financing, we work with reputable lenders to help homeowners secure funding. Read more about financing your guest home.
Building a Guest House – What to Know Before You Start
Feasibility as the First Step
A feasibility study is the first and most critical step in determining whether you can build a guest house on your property. Our analysis evaluates zoning regulations, existing site conditions, utility access, and any potential roadblocks that could impact the project. Completing a feasibility study upfront ensures that the project is financially and practically viable before moving forward with design and permitting.
Building Process
Building a guest house involves several steps, including the feasibility study, design, permitting, and construction. The entire process can take 12 to 18 months, with design taking 3 to 4 months, permitting taking 3 to 6 months, and construction taking 6 to 8 months.
Choosing a pre-approved plan or SnapADU Build Ready design can help speed up the design and permitting process and minimize delays. The most common issues that affect guest house project timelines include city permitting delays, additional approvals required for coastal zones or HOAs, utility upgrades, and plan modifications. Read more about factors that affect project timeline.
Choosing the Right Guest House Builder
Working with Guest House Contractors
Hiring a reputable and licensed builder is crucial for ensuring a smooth construction process. A good builder will help with design, permitting, and construction while keeping the project on schedule and within budget. When choosing a builder, consider:
- Their experience with ADUs and guest houses
- Customer reviews and testimonials
- Licensing and insurance status
- Their ability to provide accurate quotes and timelines
Getting multiple quotes and checking references can help you avoid common pitfalls and ensure you select a builder who aligns with your goals. We recommend reading through our detailed blog post on choosing your guest house contractor.
Top Guest House Builders in San Diego: Why SnapADU?
At SnapADU, we specialize in designing and building guest houses throughout San Diego County. With extensive experience in designing and building over 150 ADUs, we understand the complexities involved and offer comprehensive services, including custom design, permitting, and ADU construction. Our expertise ensures that each project is completed smoothly, on time, and in compliance with all local regulations. Whether you’re building for flex space, guests, multigenerational living, or even as a rental, SnapADU delivers high quality, well designed guest houses that maximize your property’s potential!
0 Comments