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Add a Second Living Space to Your Sacramento Home
An attached ADU is a new room or set of rooms added directly to your existing home. It shares a wall or roofline with your house, but it has its own front door, kitchen, bathroom, and sleeping area. No one has to walk through the main house to get in or out.
People build attached units for different reasons. Some want a parent to live next door so family can help with daily tasks. Others want to rent the space to a tenant and use that money to pay the mortgage. Also, some homeowners just need more room as their family grows. This type of addition takes less yard space than building a brand-new backyard house.
Our team at ADU Contractors Sacramento runs the project from the first sketch to the final city inspection. We draw the plans, get the permits, do the structural work, and finish the interior. This means you have one number to call for everything.
Pick the Right Addition Size for Your Lot
Attached ADUs come in different sizes. The right size depends on your lot, your budget, and how you plan to use the space.
Small Studio Suite Additions
A studio addition gives you one open living area with a sleeping space, a kitchen counter, and a bathroom. These units run between 300 and 499 square feet. They work well when your side yard is narrow or when you want the lowest possible build cost.
We frame the studio walls using solid-sawn douglas fir wall studs. Before we close the walls, we test the lumber for moisture using a wood moisture content sliding-hammer probe. This probe drives a small pin into the wood and reads the exact water content inside the stud. Wet wood warps and cracks after drywalling. This check satisfies CBC Section 2308.5.3, which requires structural lumber to fall within safe moisture limits before wall enclosure.
Single-Bedroom Attached Suite
A single-bedroom addition includes a separate bedroom, a living room, and a full kitchen. These units cover between 500 and 799 square feet. This size is most common for aging parents who need a private but connected space.
We bolt the new wall framing to the existing house using heavy-duty steel seismic hold-downs. Each hold-down is torqued to a specific foot-pound rating using a calibrated dial-indicating torque wrench. This wrench clicks when the correct tension is reached so there is no guessing. This connection method complies with CBC Section 2308.6, which sets the seismic wall shear and hold-down anchor standards for residential addition framing.
Double-Bedroom Attached Addition
A two-bedroom addition gives you two private bedrooms, a dining area, and a full kitchen. These additions run from 800 to 1,200 square feet. Under California law, 1,200 square feet is the largest an attached ADU can be. This layout works for long-term tenants or a full family.
We pour a post-tensioned concrete slab foundation under the addition. Post-tensioned slabs use steel cables under tension to resist cracking in Sacramento’s clay soils. Before we frame the walls, we test the slab hardness with a rebound concrete test hammer. This tool bounces a spring-loaded tip off the surface and gives a reading based on how hard the concrete is. This process satisfies CBC Section 1808.6, which sets foundation design rules for soil with high expansion potential.
Second-Story and Above-Garage Additions
A two-story addition builds up instead of out. This is useful when your lot does not have room to expand sideways. Some homeowners build a second living level above their attached garage or add a second floor to an existing single-story wing.
We use structural steel I-beams to carry the floor load between levels. Each beam connection is tested with a hollow-plunger hydraulic tension ram. This tool attaches to the anchor bolt and pulls it to a set load to confirm the bolt will hold under weight. This engineering step meets California Building Code Section 1604.3, which governs the maximum allowable deflection and load capacity for residential floors above occupied spaces.
What Makes Our Attached ADU Work Different
Adding onto a house is harder than people expect. You are opening up walls, connecting new framing to old framing, and tying new plumbing into pipes that were built decades ago. This requires careful planning and skilled tradespeople.
Here is what sets our work apart.
We Start With a Structural Review
Before we design anything, we look at your existing home. We check the foundation depth, the wall framing type, and the roof structure. This tells us exactly how to connect the addition without putting stress on your existing home. Next, we bring in a licensed structural engineer to review any load-bearing changes. This protects your home from day one.
We Work Inside Every Sacramento Permit Office
Attached ADU permits go through a different review than detached permits. The plan checkers look for fire separation details, seismic connections, and energy compliance specific to home additions. We know what each reviewer looks for. Also, we submit complete plan packages the first time to cut down on back-and-forth revisions.
Your Budget Does Not Change Mid-Build
We give you a full line-item estimate before we pull the first permit. The estimate covers engineering fees, city permit costs, plumbing connections, electrical work, and all interior finishes. If we open a wall and find a problem, we stop and call you. Nothing happens to your budget without your go-ahead.
All Work Is Done by Our Crew
We do not pass your project to a network of subcontractors you have never met. Our own carpenters, plumbers, and electricians do the work. This means fewer scheduling gaps, better quality control, and faster build times.
Areas of Sacramento We Build In
Sacramento is a big city with very different neighborhoods. Each area comes with its own property types and zoning rules.
East Sacramento & Curtis Park
These streets have some of the oldest homes in the city. Many have shallow brick foundations. We design the additional footing depths to match and protect the existing structure during excavation.
Midtown and Downtown
Lots are narrow here. We often design slim side-yard additions that use the full depth of the lot to create the most floor space possible within the legal setback lines.
Natomas and North Sacramento
Parts of Natomas sit in FEMA flood zones. We raise additional floor levels above the base flood elevation and use flood-resistant materials at the foundation level.
Arden-Arcade and Carmichael:
These neighborhoods have wider lots. Homeowners here often add full two-bedroom attached wings. We design these as large, well-lit additions with separate patios and private entrances.
How We Connect the Addition to Your House
The structural connection between your old home and your new addition is the most important part of the build. A bad connection can crack drywall, shift floors, and fail during an earthquake.
STEP 01
Scan the Existing Foundation
First, we locate all steel reinforcing bars hidden inside your current concrete slab. We do this before any drilling begins so we do not cut through existing steel.
STEP 02
Anchor the Two Slabs Together
Next, we drill into your existing foundation and set steel dowels using structural epoxy. This ties the new slab to the old one so both move together during ground shift or seismic activity.
STEP 03
Build and Seal the Shared Fire Wall
After the foundations are connected, we frame the wall that separates the two living units. We seal every gap around wires and pipes with fire-stop sealant.
STEP 04
Run Dedicated Power and HVAC
Finally, we wire a separate electrical sub-panel for the addition and install a ductless mini-split heating and cooling system. This keeps both units fully independent for power and air circulation.
Common Questions About Attached ADUs in Sacramento
How large can an attached ADU be?
An attached ADU can be up to 50% of your main home’s total living area, with a maximum cap of 1,200 square feet. For example, if your house is 2,000 square feet, your attached ADU can be up to 1,000 square feet. California also gives every homeowner the right to build at least 850 square feet regardless of lot size.
Do I need solar panels on an attached ADU in Sacramento?
No. California’s Title 24 solar panel rule only covers brand-new standalone structures. An attached ADU is an addition to an existing home, so solar panels are not required. The only exception is if your project scope triggers a full home energy upgrade, which is rare.
What setbacks apply to an attached ADU?
Under California state law, your addition must sit at least 4 feet from the rear and side property lines. The front setback follows the same rules as the primary home’s zoning. We confirm your setbacks during the first site visit before any design work begins.
Does my attached ADU need its own front door?
Yes. California law requires every ADU to have its own private entrance on the exterior of the home. The tenant must be able to enter and exit without walking through the main house. An interior door connecting the two units is allowed as a second access point but cannot be the only entry.
Will my property taxes go up if I add an attached ADU?
Yes, but only on the new addition. California law prevents a full property reassessment when you add an ADU. The county tax assessor will only assign a taxable value to the new square footage. Your existing home’s assessed value stays the same.
How long does it take to build an attached ADU?
From permit submission to move-in, most attached ADU projects take 6 to 12 months. Projects in historic overlay zones take longer because the design goes through an extra review step. We track your permit status and keep you updated throughout the process.
Do I need to upgrade my home's electrical panel?
In most cases, yes. Adding an attached unit with a kitchen and HVAC adds a significant electrical load. We typically upgrade the main panel or add a 100-Amp sub-panel to handle that load safely. We include this in your initial estimate.
What is the difference between an attached ADU and a Junior ADU (JADU)?
An attached ADU is a brand-new physical addition built onto the outside of the home. It can be up to 1,200 square feet. A JADU is built by converting existing space inside the home, such as a bedroom or den. A JADU is limited to 500 square feet and requires the owner to live on the property. An attached ADU has no owner-occupancy requirement.
Take the First Step Today
An attached addition gives your family more options without giving up your yard. It can house a parent, bring in rental income, or give you a quiet place to work just steps from your door.
We start every project with a free site visit. We walk your yard, check the utility locations, measure the setbacks, and review your zoning. By the end of that visit, you know exactly what you can build and what it will take to get there.
No sales pressure. No guesswork. Just straight answers from builders who have completed attached ADU projects across Sacramento.