1200 Sq Ft ADU Cost: From Blueprint to Budget

Who Do You Contact to Develop a Blueprint for a 1200 Sq Ft ADU?

Experienced builders and contractors may offer blueprint and design services for accessory dwelling units (ADUs). Some may specialize in detached ADUs, while others specialize in interior or detached ADUs. Some contractors charge hourly rates of $50 to $200. Others charge a flat rate of $1000 to $5000, depending on the scope of the project. 

Many people first contact a professional architect to draw a blueprint for an ADU. However, architects charge between $5000 and $20,000 for home renovations and ADUs. Since attached and internal ADUs are similar to home renovations, hiring an architect to provide an ADU blueprint according to your specifications can be expensive. 

Moreover, if you want to build a detached ADU, be aware that architects charge between five and 15 percent of the total cost of the project. 

Alternatives to Architects

RenoFi Design can help make your vision of an ADU come to life affordably and dependably. Once you send a phone scan of your property, we will match you with a skilled designer specializing in space planning for ADUs. Contact us to learn more about this service, which also includes estimates and preliminary designs.

How Much Does It Cost to Build a 1200 Sq Ft ADU?

Remember that multiple factors can increase or decrease the average cost of building an ADU. For example, constructing a detached ADU will cost more than transforming a basement or upper garage area into an ADU. Expenses will vary based on who you hire to create a blueprint, build the ADU, and install utility systems. The choice of finishes, materials, carpeting, and insulation will also affect the overall cost of the project. 

Average Cost of Building an Interior or Attached Accessory Dwelling Unit

Permits, regulatory costs, and fees: Expect to pay several hundred dollars to as much as several thousand dollars for complying with local building laws. Call your county’s building and zoning department to find out how much to expect to pay for permits and inspections, if applicable.

• Preparing the Area for the ADU: Basements or cellars may require extensive preparation before starting construction, such as excavation, waterproofing walls and floors, foundation inspections, and other related work. Depending on what is needed to adequately prepare the location, the preparation cost can average between $1000 to $5000 (or more). 
• Paneling, Drywall, and Paint: If an interior ADU requires wall remodeling and painting, set aside at least $5000 of your budget to cover this part of the building process.
• Flooring: Vinyl flooring is the least expensive floor material, at around $5 per square foot. Laminate flooring averages $3 to $9 per square foot. Hardwood flooring prices vary according to wood grade, finish, and type. Average hardwood flooring costs are between $9 and $16 per square foot. Carpeting is optional and will add several hundred dollars to the total cost of an interior ADU.
• Plywood Cabinets: $100 to $300 per linear foot
• Medium-Density Fiberboard (MDF) Cabinets: $80 to $200 per linear foot
• Appliances (refrigerator, stove, microwave, and other miscellaneous items): $500 to $800 for a refrigerator; $900 to $1100 for a gas range; $500 to $800 for an electric range; $300 to $600 for a microwave
• Electrical and Plumbing Installation: The cost to connect the primary home’s electrical and plumbing systems to an attached ADU varies depending on the work involved and whether contractors encounter unexpected problems. The total estimate for plumbing and electrical hookups could be between $3000 and $10,000.

Total Estimated Cost of Building a 1200 sq ft Attached ADU

• At the low end: $100,000 - $150,000
• At the high end: $300,000+

Cost of Building a 1200 Sq Ft Detached ADU

Designing and building a detached ADU is similar to designing and building a one-bedroom cottage or extended studio apartment. Most materials used to construct a new home, such as roofing, gutters, doors, windows, foundation elements, drywall, flooring, and insulation, are also used to build a 1200 sq ft detached ADU.

Obtaining permits for a separate dwelling on your property may be more expensive than permits needed for attached ADUs. Properties that are relatively level and unobstructed by trees shouldn’t require much preparation except for installing sewer and water lines. A site evaluation should be done regardless of the property’s condition to ensure the ground can support an ADU’s foundation. 

Consider building an attached or interior ADU instead of a detached ADU if an inspector finds that your property has the following:

• Poor soil quality (loose, clay, or silty soil)
• A high water table (flooding risk, increased moisture leading to premature settling and instability)
• High levels of organic materials in the soil (continuous decomposition could cause instability and voids (empty pockets) underneath topsoil
• Excessively compacted soil (compromises adequate drainage needed to prevent water pooling and foundational damage due to water pressure)

Blueprint Cost for a 1200 Sq Ft ADU

Architects or designers creating a blueprint for a detached ADU often charge 10% to 15% of the total cost of the project. For example, if the total cost of building your ADU is $140,000, you can expect a designer to charge at least $14,000 for their services. 

Blueprints include the following items: 

• Property layout (features, landscaping components, location of structures near the ADU)
• Floor plan (room sizes, placement of rooms in the ADU, placement of walls, windows, and doors)
• Foundation type and dimensions
• Wall and floor dimensions
• Framing materials and structural supports
• Roof details such as pitch, material type, and drainage system
• Location of interior electrical switches and outlets
• Circuit panel placement inside the ADU
• Layout of water pipes
• Location of showers, sinks, toilets, and other plumbing-related fixtures
• HVAC system details, including vent and duct placement
• Roof dimensions and slope
• Accessibility features (ramps, handrails, etc.)

Your blueprint will also provide information about the building code and zoning compliance necessary to complete the project. 

Here is an estimated itemized expense list for a 1200 sq ft detached ADU:

• Materials (lumber, brick, siding, roofing, doors, gutters, and all other components needed to construct the ADU): at least 50 percent of the total cost. For example, if the total cost is expected to be around $150,000, the cost of materials will average between $70,000 and $80,000. 
• Site Preparation (tree/stump removal, leveling, evaluation of soil quality): minimal site preparation should cost around $1000 to $2000. When extensive preparation work is required, the cost could exceed $5000. 
• Laying the Foundation: A popular foundation type is the monolithic concrete slab, which costs around $6000 for a 1200 sq ft detached ADU. Although cinder block foundations are typically $1000 less than a monolithic concrete slab, they do not provide the strong support and durability that concrete slabs do.
• Lumber Framing: The average cost of lumber for framing ranges from $20,000 to $25,000. Metal framing is more expensive and costs 10 percent to 15 percent more than lumber framing.
• Installing Electrical and Plumbing Systems: Depending on the type of HVAC system used in a detached ADU, expect to pay between $4000 and $10,000 to have water and power installed. 
• Labor (plumbers, electricians, general and subcontractors, designers, architects): Allocate at least 40 percent of your budget towards paying for labor expenses. 
• Permits and Miscellaneous: Set aside about $2000 to $4000 for purchasing permits and covering unexpected expenses.

What to Know About Solar-Powered Detached ADUs

You can place photovoltaic panels on a detached ADU’s rooftop just like you can a primary residence. Although a solar-powered ADU would incur an additional cost of at least $10,000, the long-term return on investment (ROI) pays for itself by nearly eliminating future electricity costs. Depending on the energy needs of the person living in the detached ADU and the available roof space, a system size ranging from three kW to six kW should be sufficient.

Get Started on Your 1200 Sq Ft ADU 

Understanding the cost of a 1200 sq ft ADU from blueprint to budget really comes down to some careful planning and budgeting on your part as the homeowner. By considering a number of factors such as the design complexity, materials needed, labor, permits required, and other unexpected expenses, you can anticipate the financial requirements for the job at hand.

RenoFi loans offer the best flexible financing options for home renovations involving ADUs or other remodeling projects. At RenoFi, you can secure the loans necessary to achieve your goals without compromising your financial stability or mortgage terms.

Loan amounts are awarded to homeowners based on the estimated value of their home after the renovation is complete. It’s as simple as that!

RenoFi loans are the smartest way to finance a home renovation project. Unlike traditional loans, which are based on your current home value or require you to refinance your primary mortgage and give up your low rate, RenoFi loans are based on the after renovation value of your home. This allows you to borrow, on average, 11x more, get a low monthly payment, and keep your low rate on your first mortgage.

Contact us today to learn how to get the funds you need to build a 1200 sq ft ADU from blueprint to budget.