Accessory Dwelling Units: Helpful Tips to Navigate

Episode 24: Welcome to the She Builds Show, I’m your host, Stefanie Olson. Today, I want to talk to you about this little thing called an ADU… An ADU is an accessory dwelling unit, these units can be put on your property to add office space, extra living space for family members, a gym, or my favorite, rentals for extra income. So today, I want to give you a few tips to help you down this road, if this is something you’re thinking about. So the first and most important thing to think about is your zoning and whether or not it actually allows for an additional space. There are two ways to find this out, you can call your local city or county you live in and ask some nice person on the phone. Most cities and counties have what’s called an interactive zoning map where you can put in your address and you can see what your zoning is and what it allows in our city. Most residential lots allow for an additional unit.

Let’s talk about ADU’s. Ready?


•  So an attached ADU can only be maximum 50% of the living area of the main residence with a maximum of 1200 square feet. If it’s a detached ADU, they’re generally maxed out at 800 square feet. Now, there are rules to accommodate if you want something larger, but you can only go 50% of the living area of the main residents. Again, maxing out at 1200 square feet. So a simple little example, If you want a detached ADU, you can go up to 800 square feet, no problem. If you wanted to go larger than that, and you had a 1500 square foot house, 50% of that main house is 750, so you couldn’t go larger than 800, your main house has to be bigger to accommodate something. (01:53)

•  The other item that I just want you to consider is your utilities. So our city allows you to hook up to existing water and sewer lines, this is a huge deal because it really saves money not having to put in additional underground utilities. Now, the other item to discuss here is septic tank, so we have a lot of septic tanks in the area that I live… The city here will allow you to hook up to an existing septic tank if the tank and leach field is big enough to handle the additional load. Let’s talk septic tanks for a second. So, the size of the tank determines whether or not you can put in additional load on that tank. A 1500-gallon tank usually is for a three-bedroom house, and the tank load is determined by bedrooms, not bathrooms, so if you already have a three-bedroom house and you’re adding a one-bedroom unit and you have a 1500 gallon tank, your tank would be maxed out.  (04:16)

•  A master plan is a floor plan that has already been through a building and planning check and has a set of plans ready to roll. This is my favorite way to expedite the building process, and it also saves a lot of money. In Chico, they have over 20 master plans ready to use, and they range in size from 496 square feet to 749 square feet. These plans are on their website and you can view in the ADU catalog. It saves so much time and money, you guys always consider a master plan, even if the floor plan isn’t exactly what you want, because small modifications can be made without paying a fortune. Starting from scratch from an architect or engineer from the get-go, is quadrupled the price versus using a master plan, so always consider this and check out your local city or county to see if they offer anything like that.  (6:42)

•  So the other thing to consider is your financials, you can get a construction loan for a new build, so any local lender can help you through that process and just make sure you’re considering the financial part as part of your plan. Now, once you have your plans ready for submittal, you can either submit them as an Owner Builder or you can have a Contractor submit the plans for you. Now, there will be permit fees and school fees that need to be paid at this stage, so make sure you bring your checkbook when you’re going to submit plans, then once you get the permit, you’re ready to start building.  (8:22)


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