Real Estate

How Much Does an In-Law Suite Addition Cost in SanDiego, CA?

Law Suite Addition Cost in SanDiego, CA

An in-law suite, also commonly called an accessory dwelling unit, is a self-contained unit that has a full kitchen and bathroom as well as a private entrance.  An in-law suite addition is a great way to make space for family to reside in your home while maintaining some privacy and independence.  Before you begin your ADU building process, consider what you are building the suite for.  Will you have aging parents living in the addition?  Will you use it for a rental?  Or will it be used by adult children who are between school and full time careers?  What you intend to use your ADU addition for will determine the materials you use and the size of the structure.

The average cost to build an in-law suite addition is $82,500.  This number is just an average cost and the price to build can range between $40,000 and $125,000.  Of course these prices represent such a wide range because of variations in choice of material, cost of labor, and necessary structural and/or utility work.

Material Costs

Building an addition will require structural work to the main house which means you will need to hire an architect and a contractor to oversee zoning and the structural integrity of the addition.  Sub-contractors such as an electrician, plumber, and HVAC.  In addition to the cost of hiring a contractor you will have material expenses for such as but not limited to:

Support beams

            Roof trusses

            Drywall and insulation

            Foundation materials

            Bathroom plumbing

            Plumbing fixtures

            Electric meter

            Water heater






In-Law suite Addition Costs by Size


In-law suites can vary dramatically in size depending upon the area available and the amount of money you would like to spend.  While you can calculate the cost of the addition by size, remember that the total cost will be greatly influenced by the materials and upgrades used. Average costs by size are approximately:

400 square feet costs $40,000-$80,000

500 square feet costs $50,000-$100,000

600 square feet costs $60,000-$120,000

750 square foot costs $75,000-$150,000

In-Law Suite Addition Upgrades to Consider


When designing an ADU remember to make it safe, liveable, and adaptable in the event that you sell your home in the near future.  Top real estate agents in the San Diego, California area have seen an increased interest in ADUs over the past two years.  Some homes with an in-law suite can sell for 35% more than those without.  To guarantee that your in-law suite addition increases your home’s value, you should incorporate popular The top three design elements to boost the value of your ADU are durable flooring such as waterproof laminate, plenty of natural light, and granite countertops and name-brand appliances in the kitchen.

While the total cost to build an in-law suite can be high, it will increase your home’s value.  You could see an increase of up to 30% in your property value by investing in an in-law suite.  An accessory dwelling unit will add square footage to your home’s resale value, which will be represented in your home’s appraisal.  ADUs can appraise for more than it costs to construct them, depending on the location, square footage, number of bedrooms and bathrooms, HVAC, age of the property, quality of the build, state of the real estate market, and additional comps.



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