One of the toughest parts of building an ADU is deciding on a floor plan that meets all of your county’s rules for construction, and getting this floor plan approved by local officials.
That’s why some counties have a solution: pre-approved ADU floor plans. These are certain ADU floor plans that have been marked as “pre-approved,” which means unless you’re in a unique circumstance, you’ll be able to get through the permitting process much more easily knowing your floor plan has been used and approved before.
Whether you’re considering a 1 bedroom ADU or a 2 bedroom ADU, an ADU converted from a garage, an ADU attached to the house, or a stand-alone detached ADU, there are many example floor plans that you can use that have been pre-approved in certain counties.
“ADUs are the most innovative new solution to the affordable housing crisis,” says Justin Goldman, RenoFi CEO. “But they also come with a lot of permitting challenges. Using a pre-approved ADU plan, if it’s available, is a great way to avoid those challenges.”
While you may have already decided which type of ADU best suits your needs, it is legally required to check with your county or city’s ADU development requirements before constructing it. You must obtain the necessary permits and approvals for your project.
While the conversion ADU is the most affordable option, it offers the smallest amount of space. The attached ADU is more expensive than the conversion, but the detached ADU is the most expensive of them all, and is only suitable for large lots.
In this article, we’ll cover some of our favorite pre-approved blueprints that have already passed the requirements for their respective county or city. We’ll share some plans used in California, as well as Washington, D.C.
What is an approved ADU floor plan?
According to this study conducted by UC Berkeley, building an ADU in line with the city/ county’s requirements is one of the largest challenges new prospective ADU owners face.
There are two initial choices you have for building an ADU:
- A prefab or manufactured ADU
- A custom or stick-built ADU.
A custom or stick-built ADU is a structure that has not been prefabricated and is built on-site. Prefab or manufactured ADUs are manufactured off-site and transported to their final destination.
Prefab ADU companies often make claims that their ADUs can be installed quickly, but this doesn’t include the time you need to spend getting a construction permit, and not all prefab ADUs are pre-approved plans.
Make sure to take this into consideration when you’re choosing your construction path. Every ADU, whether prefab or custom, pre-approved or not, requires city permitting.
Also, you currently cannot use a RenoFi Loan to finance prefab/manufactured ADUs.
What does “pre-approved” mean?
The phrase pre-approved is a bit misleading. Pre-approved does not mean “doesn’t require approval." It just means the city has already deemed the plan to be code-compliant. So you still need approval, it will just be slightly less time-consuming.
Pre-approved plans still require a permit, and if you’re using a RenoFi Loan to finance it you will still need to submit ADU plans for review.
Choosing a floor plan
The first step to choosing a floor plan is finding inspiration for your project.
It always pays to dream big and take the time to inspire and immerse yourself in the projects other people have shared for the rest of the world to see.
And to help get you thinking about what could be possible, we love Houzz’s outbuildings ideabook and ADU ideas & photos collection, as well as Pinterest (of course!) and Dwell’s round-up of 29 Granny Flats That Put Guests Up in Style.
The next step is nailing down a floor plan.
ADU standard plan policy
ADU pre-approved plans can help homeowners save time and money, but there is one caveat. Just because you use a pre-approved plan, that does not mean you won’t need a building permit or any construction site checks.
So what’s the policy?
Pre-approved plans still must go through the normal site-specific checks (i.e. arborists and site surveyors) in order for the project to receive a permit.
Can you make any edits or changes to pre-approved plans?
Most, but not all, cities with pre-approved plans allow homeowners to make small changes to pre-approved designs, including adding larger windows or changing the exterior materials.
What do you do if your city doesn’t have pre-approved plans?
If you are in a county that does not have standard approved plans, consider taking a blueprint to your local office and see if you can have it approved for future ADU builders.
Approved plans in top cities
If you’re looking to build an ADU in cities such as: Los Angeles, San Francisco, Washington, D.C., San Jose and Seattle, your local government may provide “Approved Standard Plans”.
These are blueprints that have been reviewed and pre-approved for compliance with the local Building, Residential, and Green Codes.
However, please note that these pre-approved Standard Plans may not be approved for use in certain situations and/or site conditions.
For example, for standard plans with roof decks, the roof decks may require additional setbacks in specific zones.
These are our favorite approved blueprints in these top cities for you to consider:
Los Angeles has potentially the longest list of Standard ADU plans to choose from, thanks to a city initiative that went into effect in 2021.
The Los Angeles Department of Building and Safety (LADBS) created a website that houses all of the potential standard plans. You can check out over 20 different plans at that link.
You should note that you’ll still have to purchase each of these plans from the designers listed; they are not free.
There are lots of options on the list linked above, but this is the design firm and plan that we like best: Cottage.
Cottage is a full-service ADU company that helps from the design stage to the permit stage all the way to the construction stage.
While Cottage has many different ADU plans and provides custom builds, there are two plans deemed pre-approved by LA officials.
Minor, non-structural changes such as changes to window/door types and sizes and/or rotating the floor plan are allowed, but further floor plan / structural changes are not allowed when using a Standard Plan.
For the full list of LA Standard plans, check out the LADBS website.
San Francisco doesn’t have a comprehensive list of pre-approved or standard ADU plans. Bummer! But there are still some approved prototypes that you can work off of to speed up the process.
In 2015, the San Francisco Planning Department and Openscope Studios compiled an ADU guide for homeowners in the city. This guide contains several prototypes that contractors and homeowners can use as guides for their blueprints, but they are not fully pre-approved.
Unlike LA, San Francisco homes don’t generally have large backyards or side yards. Instead, you probably have space underground in a basement. This can make the ADU design process a little tricky!
Prototype A (Page 37 of the ADU guide) Partial garage conversion of a single-family home with an open ground floor
- We love this ADU because it still leaves room for a covered parking space! This partial garage conversion features a long, narrow exit hallway that opens right to the exterior sidewalk in front of the house.
- The bedroom and primary living space is arranged to maximize access to natural light coming in from the back of the house.
- You can also still have room to enjoy a kitchen, bath, and dining space.
Prototype D (Page 58 of the ADU guide) Full garage conversion of a single-family home with an open ground floor:
- Similar to the first, except no room to park. This floor plan, however, gives you way more living space–including an extra bedroom! It is located on the ground floor of a single family home, utilizing as much of the ground floor as possible.
- Imagine replacing the garage door with aesthetically pleasing new windows and a swing door. Each bedroom (one in the front and one in the rear) has access to natural light.
Prototype E (Page 64 of the ADU guide) Full conversion of a freestanding garage:
- In San Francisco, it is not uncommon to find a small free-standing one-story garage built adjacent to the main house. The garage is usually built near the front property line, but you may need to raise the roof in order to have enough headroom.
- Imagine replacing the garage door with a swing door, windows and adding a skylight to the ceiling.
- While this space is often not as large, you’ll enjoy more privacy from the other two floor plans (since it’s a freestanding structure), making this plan one of our favorites.
The city of San Jose has a list of pre-approved ADU plans on their government website. One thing to note is that in San Jose, all pre-approved plans must be detached properties. They do not include garage conversions or additions.
The list on the website offers nine ADU design companies that offer pre-approved plans in the city of San Jose.
Here is our top pick and why we like them:
Acton ADU offers the most pre-approved plans, four total, of all the design firms that are on the San Jose list.
We like Acton’s plans because they’ve been in business for over 30 years, and none of their ADUs are factory-produced. They are all traditionally made, and fit the standards of permanent residences. Acton even provides interior design services if you’re looking for a beginning-to-end full scope ADU service.
Check out all of their pre-approved designs here. Each of the four pre-approved blueprints below also comes with four different floor plan variations, respectively, that you can choose from.
- 364 sq. ft. 1 bedroom ADU
- 440 sq. ft. 1 bedroom ADU (3D model)
- 560 sq. ft. 1 bedroom ADU (3D model)
- 748 sq. ft. 2 bedroom ADU
The website actually refers to the ADUs as DADUs, which stands for Detached Accessory Dwelling Units. Seattle’s city government does not have any pre-approved plans for garage conversions or attached ADU’s.
There are currently 10 pre-approved plans on Seattle’s list that are verified by Seattle Department of Construction and Inspections (SDCI) that you can check out.
Here is our top pick and why we like them:
The Cedar Cottage, designed by CAST Architecture, is an extremely efficient footprint that provides flexibility on many sites, including sloped ones or covered outdoor porch space. Plus, it provides easy expandability for families or roommates as a two-bedroom model.
We love that the Cedar has a generous central entry that connects to all spaces.
Our other favorite part about it is that it is a green building. The design is targeting Built Green 4 Star; reduced air infiltration; energy efficient heating; cooling and water heating systems; passive solar heat gain in window/shading in summer; low-VOC, recycled and renewable materials; no fossil fuel appliances; and all-LED lighting.
This design is unique in its efficiency and is sure to help you save on energy bills moving forward.
Here are the specs for the Cedar Cottage plan:
- 1 bed, with 2 bed option
- 467 sf
CAST Architecture has several other ADU designs, but the Cedar Cottage is the only one pre-approved in the city of Seattle.
Check out the full list of pre-approved ADU plans for Seattle.
As of November 2021, Washington, D.C. residents have two pre-approved ADU plans for one bedroom units they can utilize to speed up the permit process.
Because the program is quite new, there’s no dedicated website explaining these two options. However, Washington, D.C. does offer a unique platform with a streamlined process for building inspections, once you already have a proposal.
The two Washington, D.C. pre-approved plans:
The first of the pre-approved options, Backyard Container, is pre-fabricated, which means it cannot currently be financed through a RenoFi Loan.
However, the other ADU pre-approved plan is stick-build and created by a local architect who’s an expert in ADU designs. Since 2019, the year ADUs were legalized in Washington, D.C., architect Illeana Schinder has designed over 20 ADUs.
The architect is a local ADU expert that’s even written a good portion of the government D.C. ADU Manual.
Here’s more info on Illeana Schinder’s pre-approved ADU plan:
- 416 sf
- One bedroom
- Plan cost: $4,000 - $6,000
- Includes solar panels, rain barrel, electric car charger
For full detailed architectural plans for The Alice, click here.
Other cities with pre-approved standard ADU plans
While we didn’t cover these cities in this article, there are several other places that have government-approved lists of standard ADU plans.
These are the other cities that currently have pre-approved plans with links to the government websites listing them:
With decreasing legal restrictions for ADUs in many areas, more cities will hopefully join this list in the coming years.
Additional ADU information
While finding a pre-approved plan for an ADU is a great first step, you’ll probably need to find some way to finance your ADU project.
Even though ADUs are basically smaller versions of full blown homes, they don’t have a full blown mortgage option that you’re probably used to. So many homeowners are left scratching their head as to where to find the right loan.
That’s where RenoFi Loans come in - one of the top loan options for financing ADUs nationwide. RenoFi Loans let you borrow based on your future home equity, including the value of your ADU. This means you can borrow much more than you’d be able to with a traditional home equity loan.
To read more about RenoFi Loans and other ADU financing options, check out 6 loan options to finance an ADU.