Before Building an ADU, Ask Yourself These 4 Questions

It’s nearly impossible to live in Sacramento, Folsom, or Roseville without hearing about Accessory Dwelling Units, or ADUs. But what exactly is an ADU, and should you add one to your property? 

The California Department of Housing defines an ADU as “a secondary dwelling unit with complete independent living facilities for one or more persons.” When certain specifications are met, an ADU allows for streamlined permitting, no new land costs, and the addition of a structure where previously it would have been forbidden by the building code. These new regulations help to tackle the housing crisis that is facing much of California (a crisis which is felt acutely in the Sacramento region). 

However, while they may be the current hot commodity, ADU projects do not make sense for everyone, and are not available to all property owners. To see if constructing an ADU is possible and feasible for you, you should first answer these four major questions.

1: Will the building department allow an ADU in my backyard?

Despite their popularity, not every property is automatically zoned for an ADU. Sacramento City has a great online tool that will help you determine if you can place a potential ADU building on your property, and most other municipalities or counties also have online guides. However, this question delves into the heart of building codes and can become potentially messy. Answering this question may require not only spending a few hours on your local municipality website, but also talking to experienced professionals who are familiar with specific local codes, such as an architect, designer, or contractor. You may also choose to talk about your site with the local building department.

Once you have confirmed that your local building department will allow an ADU on your property, an aspiring ADU builder needs to ask:

2: Does my site allow for an ADU?

While with enough money and desire nearly anything is possible, unless you are independently wealthy, it’s best to only build where practical.

So what are the practical site considerations for building an ADU in Sacramento? First, you need to determine if there is realistically enough space for the new structure. Can the ADU be built under an existing roof or with a small addition attached to the home? Is there room for parking? As anyone would expect, the initial home on the site is usually located on the best spot on the lot. With some luck, there will be a secondary place to add an ADU. However, if your site has one flat spot where the main house currently sits, while the rest of the lot has an extreme slope, it may be technically possible to add an ADU, but not as feasible or cost-effective as if you had a flat and buildable site.

If there is space, the next consideration is:

3: Are there existing utilities?

Sewer, Water, Electrical, and sometimes drainage are the most important utilities to consider. If your site is in a rural Sacramento area, sewer will likely be the most significant utility as septic systems are generally built for the existing home size and may need to be increased in size for an ADU (which is a fairly expensive undertaking). If your home is in a city, it's always much more straightforward to connect to the city sewer, especially since many municipalities have subsidized the connection cost for ADUs. However, connecting your ADU to the city sewer could still be cost prohibitive if your site is located below the main city connection and a lift station or ejector pump is needed. Additionally, it’s important to consider the route that must be trenched. Is it a straight, uninterrupted trench through dirt? Or would the new connection include tearing up the driveway or other expensive finished areas? While the former is easier, the latter can decrease the feasibility of the project.  

The same general thinking must also be applied to the electrical system. What route will the new wires take? Many ADUs are required to be all electric without gas appliances and therefore have a higher electrical draw. Is the existing electrical service sufficient to supply the power needed to the new residence? Or will the service need to be upgraded? All of these utility issues can be independently worked around, but if your site has multiple utility issues the cost of building an ADU can significantly increase. It's important to determine if the cost will become prohibitive prior to spending thousands of dollars on plans and permits.

This leads us to the most important question of all:

4: Should I build an ADU?

Answering this question requires a deep look into your personal situation as well as your long-term goals and alternatives.

An ADU is best suited for independent living for another person or family: that’s the scenario the government is attempting to create. An ADU could be another space for your in-laws to stay when they come and visit, or perhaps a place for your parents to live as they age. Maybe a son or daughter wants their own place but you would like to have them live nearby. And while having family in the ADU may be your first preference, the dwelling is designed to be completely independent from the primary residence—and would allow for you to rent it out to a separate person or family. Having a rentable structure also can increase your property value for you or a future buyer.

All these are great advantages, but before you begin the design of an ADU for your property, it’s important to consider your alternatives. 

These alternatives generally include purchasing another home that’s already complete. Many people consider adding an ADU in order to increase the size of their home, which may not be the best option. It’s important to first look at the housing market in the area in which you would like to live and price your options. Often, for a similar price to what your home is worth plus the capital outlay you would have to undertake to complete an ADU project, you may be able to simply buy a larger home. If moving is not in the cards for you, adding space to your existing home might be the most cost-effective way to address your design issues.

Choosing a home addition can be a great alternative to an ADU. If you want a new primary suite to live in, a simple addition may be less expensive and better suited to your needs. An ADU has multiple requirements that support independent living, such as a kitchen and sometimes independent utilities, that may be unnecessarily costly when all you really need is more or different space.

If you determine that another type of building project could suit your renovation needs, you can work with a contractor to begin to draw up a precise budget and start to plan your new space. Whatever you decide, make sure you’ve answered these four questions first—it’s always better to thoroughly consider your options instead of blindly following the (understandable) ADU hype.