Other Costs

What are the additional costs?



In order to ensure proper placement of your ADU and compliance with local jurisdictional code, you will need to have a survey performed on your property. Having this done from the outset will help mitigate any potential delays or issues if the city or inspector requires one or if a neighbor disputes the property line once the structure is completed. Property survey must be completed prior to finalization of plans for submission to the city.

Permit/City Fees


OneStop ADU is educated on the crucial thresholds for square footage that will trigger higher costs such as sewer connection and impact fees. To encourage homeowners to build casitas, many development fees have been waived. For example, the City of San Diego has waived all development impact fees for granny flats regardless of size and there are no impact fees for ADUs less than 750 sq. ft. For larger units, impact fees are related to the ratio of the size of the ADU and primary dwelling (main home). Typically, these fees run $3K-$5K. In addition to typical permit processing and plan check fees, sewer connection fees run $2-$4K with annual fees thereafter. If your property is not connected to the city sewer and a septic system is required, approvals and heftier costs will be incurred.

School fees will also need to be paid and are based on the square footage of your backyard home (typically $4-$5/sq ft) and will run $2-$5K.

Basic Site Work


The base price for site work is for a flat lot with easy equipment access to prepare for construction of your ADU. Included in this base price is typical site work such as basic grading and trenching for utilities. In addition, utilities will need to be located and the sewer line will need have a camera service in order to determine it's integrity.  It is possible that your site work will be more costly if you If you are removing another structure, hardscape, fencing or trees, have insufficient access, rerouting utilities, building on a slope, require grading, soil import or export, retaining walls, soil compaction, increase water line or meter size, new electrical panel and conduit, distance to tie into to the sewer or utilities, septic system requirement or fire sprinklers.  If a raised foundation is required, that would be at an additional cost. Other possible requirements are permitting of any unpermitted structures you are keeping, high fire risk or coastal zones, a survey if property line boundaries are unclear or a title report. These additional costs can quickly escalate, and we want to be as transparent as possible.

Upgraded Finish Materials

As per selection

Standard finish materials from our Customize your ADU page are included in our construction prices on our Plans & Costs page. Please refer to our What’s Included? page for details. OneStop ADU offers 3 styles: Contemporary, Craftsman and Spanish/Mediterranean that have been carefully curated with designer finishes selected to reflect your style of choice. Our design team has done all the leg work providing our clients with a beautiful cohesive look for your new ADU.

We Want to Hear From You

Contact OneStop ADU today. We serve owners and investors in the entire county, including San Diego, Chula Vista, Oceanside, Carlsbad, and the surrounding areas.

Scroll to Top