Accessory Dwelling Units (ADUs) are becoming a popular option for homeowners in the greater Sacramento area who want to add value to their property or create additional living space. But one of the biggest questions homeowners ask is: How much does it cost to build an ADU?
The cost to build an ADU can vary depending on many factors, such as the size, finishes, and complexity of the build. One of the most significant factors that influence the total cost is the square footage of the ADU.
Understanding Sacramento ADU Construction Costs by Square Footage
In the Sacramento area, the benchmark cost for building a medium sized ADU typically falls around $350 per square foot. For example, a standard 780 square foot detached ADU with 2 bedrooms and 1 bathroom would have an estimated base cost of:
780 sq ft x $350/sq ft = $273,000
However, this cost includes everything from framing to finishes. One of the key components that drive up the price of an ADU is the kitchen and bathroom. For many projects, these two spaces account for a large portion of the cost.
Breaking Down the Kitchen and Bathroom Costs
In most ADUs, kitchens and bathrooms are the most expensive areas to build because of the plumbing, cabinetry, appliances, and fixtures. A standard kitchen and bathroom setup can cost approximately $50,000 for an ADU build.
If you take this $50,000 kitchen and bathroom cost out of the overall price of the ADU, you can better understand how footage impacts the remaining build costs.
Comparing a 500 sq ft ADU to a 780 sq ft ADU
Let’s compare a smaller 500 square foot ADU to the 780 square foot example. A smaller ADU might come at a higher per-square-foot cost, around $390 per square foot:
500 sq ft ADU:
Total Build Cost: 500 sq ft x $390 = $195,000
Subtract the Kitchen/Bathroom Cost: $195,000 - $50,000 = $145,000
Remaining Footage Cost: $145,000 ÷ 500 sq ft = $290 per sq ft
Now, let's do the same for the 780 sq ft ADU:
780 sq ft ADU:
Total Build Cost: 780 sq ft x $350 = $273,000
Subtract the Kitchen/Bathroom Cost: $273,000 - $50,000 = $223,000
Remaining Footage Cost: $223,000 ÷ 780 sq ft = $286 per sq ft
Why Smaller ADUs Have Higher Per-Square-Foot Costs
Even though the overall build cost of the smaller ADU is lower, the per-square-foot cost is still slightly higher. This is because the fixed cost of the kitchen and bathroom doesn’t change, but there’s less square footage to distribute the remaining construction costs.
In this case, for a 500 sq ft ADU, the per-square-foot cost for the remaining footage is $290 per square foot, which is just slightly higher than the $286 per square foot cost of the 780 sq ft ADU. This reflects how the fixed kitchen and bathroom costs have a more significant impact on smaller ADUs.
The Benefits of Building Larger ADUs
If you build a larger ADU, such as one closer to the maximum allowable size of 1,200 square feet, the cost per square foot may decrease in a similar way. For example, a larger ADU could be built at around $325 per square foot. Here's what the cost might look like for a 1,200 square foot ADU with two bathrooms:
1,200 sq ft ADU:
Total Build Cost: 1,200 sq ft x $325 = $390,000
Updated Kitchen/Bathroom Cost: $65,000
Subtract the Kitchen/Bathroom Cost: $390,000 - $65,000 = $325,000
Remaining Footage Cost: $325,000 ÷ 1,200 sq ft = $271 per sq ft
As you can see, the cost per square foot of the remaining footage decreases even further for larger ADUs because the fixed kitchen and bathroom costs are spread over more square footage.
How Permits and Fees Are Affected by Footage
Another area where square footage plays a key role is in permit and impact fees. Specifically, smaller ADUs can help homeowners avoid school impact fees, which are typically applied to ADUs 750 square feet and larger. This means that building a 500 sq ft ADU would have the added benefit of reducing the overall permit costs, making the project more affordable.
For larger ADUs, these fees could apply, but the per-square-foot construction costs can go down, as discussed above.
What Affects Your ADU Costs?
Other factors that could influence the final cost of building an ADU in Sacramento include:
Site Conditions: Is there easy access to utilities? Is there a slope on the property that might require grading or retaining walls?
Materials and Finishes: High-end finishes or custom materials will increase the cost.
Permits and Fees: As mentioned, local permits, utility hook-ups, and impact fees vary depending on the size of your ADU.
Design Complexity: A more complex design or custom floor plan can also raise costs.
Non-Livable Space: Adding non-livable spaces, such as a garage or storage area, can increase costs even though these areas don’t require the same level of finish as livable space. While they can add functional value to your property, they still require foundations, roofing, and walls, which will increase the overall project cost. Including non-livable space can also impact permit costs and site requirements.
Final Thoughts
Building an ADU is a significant investment, but it can add incredible value to your property and serve a variety of purposes, from guest accommodations to rental income. Understanding how square footage affects cost is a critical first step in budgeting for your project.
At Luminist Homes, we work closely with homeowners in the greater Sacramento area to design and build ADUs that fit your needs and budget. If you’re considering adding an ADU to your property, we’d be happy to help you plan your project from start to finish.
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