What Does an ADU Cost?

The cost of an ADU may seem expensive, but it is because there are a lot of fixed costs and you have all the same expenses as building a brand new house but without any bulk discounts. You still have to pay design fees, permitting, pour a foundation, hire subs like electricians.

With a large home, the cost per square foot is offset by cheaper square footage like large livingrooms and multiple bedrooms. In a granny flat, everything is compressed, but you still have to include the expensive square footage like a kitchen and a bathroom.

Generally, the larger your ADU, the cheaper your cost per square foot. So you may be able to pay $220 a square foot for a 1200 square foot ADU and $300 per square foot for a 450 square foot ADU.

How much do permits cost?

It depends on what jurisdiction and how large you build. In San Diego, generally, people are paying $5-10K.

How much does Basis Studio charge for design, drafting and permit processing on an ADU?

Every project is different, but our fees typically start around $9,500 for a full service package to take your ADU from idea through permit approvals. We take the time to scope your project thoroughly so we can give you a full service proposal that includes everything needed to complete your project. We know how frustrating it can be to feel nickle and dimed throughout a project. That’s why our proposals are lump sum proposals with a clear scope of what is expected and included.

How long does the permitting process take?

The permitting process varies by type of ADU and Jurisdiction. 8-14 weeks from the first submittal to the city is typical for most jurisdictions. The time from the start of a project to the first submittal is largely dependent on how long the design process takes. Let us know your timeframes upfront so we can help figure if it’s a realistic timeframe. Every project is unique.

How big can I build?

A detached (stand-alone) unit can be up to 1,200 square feet un most jurisdictions, even if the main house is smaller.

If the ADU is attached to the main house you can build up to 50% of the new existing home up to a max of 1,200 sf.

Some jurisdictions have mandated different maximum build sizes that are more restrictive. In San Diego County there are different size restrictions in Carlsbad, Del Mar, El Cajon, Escondido, and Vista.

What zoning do I need for an ADU?

Single-family zoning, RS1-7. Every city has different zoning designations, but ADUs are intended as a second rentable unit for an existing or proposed SINGLE Family Residence.

Check ScoutRed.com for zoning information and overlays.

What does a coastal overlay zone mean?

Being in a coastal overlay zone for permitting reasons is more expensive, challenging and time-consuming. Because ADUs have expanded in opportunity recently, the requirements are subject to change. Make sure to sign up for our cheat sheet so we can keep you updated on changes in the requirements as they occur.

Is owner occupancy required?

The state law does not require owner occupancy, but most cities do require it. This means the owner must either live in the main house or in the accessory dwelling unit. San Diego City, Oceanside, and La Mesa DO NOT require owner occupancy.

Are vacation rentals allowed?

The state law does not restrict vacation rentals, but does allow local jurisdictions to restrict them. In San Diego County, Del Mar, Coronado, El Cajon, Encinitas, San Diego City, Solana Beach, and Oceanside have prohibited short-term rentals in a granny flat.

What setbacks are required?

The state doesn’t have a requirement for setbacks so this is dictated by a local ordinance. Existing permitted structures may be converted to ADUs on the property line, like a garage. However, if you build above a garage there’s a maximum 5-foot setback. Otherwise, it’s up to the local jurisdiction.

Is parking required? Where?

You are not required to add parking if you’re within ½ mile of public transit or are converting existing space to an ADU. There are other less common exemptions and some specific to each city. If you do a garage conversion you are required to replace the parking that was available in the garage. Cities typically define parking as 9.5 x 18’ hardscaped space or something close to those dimensions. More importantly, parking is allowed to be placed anywhere on the lot, including tandem and in the front yard.

When is a permit required?

Always for an ADU! & Almost always for everything else. Typically, you will not need a permit if the structure you’re building is classified as a shed and is less than 120 square feet and contains no utilities, otherwise, you are required to obtain building permits.

What financing options are available?

The most common ways to finance these are home equity line of credit, cash out refinance, renovation or construction loan. If you don’t have someone to assist you in financing, we have partners that we work with that we can refer you to.