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Service 03 / 11

Home Additions & ADUs

More space. Thoughtfully planned. Built to last.

Real Deal Builders builds home additions and detached ADUs, also called granny flats, from concept and permitting through construction and final inspection.

An addition asks more of the planning, the coordination, and the permit file than a remodel does, because it changes the footprint or the height of the house. We manage the process from design and plan check through permits, foundation, framing, utilities, inspections, and final finishes, and we keep every phase organized and moving.

With a typical timeline of six to fourteen months, we set realistic expectations at the start, so you can plan your household and your year around the project instead of around surprises.

Whether you are making room for a growing family, adding a private guest space, or building an ADU for long term value, we manage the process through final approval, so the finished space is permitted, inspected, and ready to live in.

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Design rendering of a single story stucco room addition off the back of a house, with a sliding glass door onto a new concrete patio and dry garden planting
Design rendering

What to expect

Home additions and ADUs at a glance

Timeline
We plan 6 to 14 months from plans to final sign off
Trades we manage
Foundation, framing, roofing, plumbing, electrical, HVAC, drywall, finishes
Permits
Required, with plan check, inspections, and final approval
Typical scope
Room addition, second story expansion, or detached ADU

How it comes together

A clear path from plans to completion

Why permits set the pace

The permit and plan check window is the single biggest factor in the timeline of an addition or an ADU. Depending on the jurisdiction and the project, approvals can run weeks or months, and every correction cycle adds to that. We account for the process from the beginning, prepare the submittal, answer the corrections, and keep the file moving toward approval rather than leaving you to work the counter alone.

Once permits are issued, construction runs in the order the city inspects it: site preparation and foundation, structural framing and the roof, rough plumbing, electrical and HVAC behind the walls, then insulation, drywall, flooring, cabinetry, exterior finish, paint, and a final inspection. We schedule around those inspections so our own crews and the licensed trades we bring in arrive when the work is ready for them.

Attached additions vs. detached ADUs

An attached addition or a second story becomes part of the existing house, so the transitions are where the work shows. Roof lines, framing connections, floor heights, exterior finish, and the trim details get resolved on paper before we frame them, so the new space reads as though it was drawn with the original house rather than bolted onto it.

A detached ADU is built as an independent living space, with its own foundation, its own utility connections, its own setbacks, and its own inspections. We coordinate the planning and the approvals and we build the unit itself, so what you end up with is a permitted dwelling rather than a shed with plumbing.

What decides your timeline

No two additions run the same calendar. Complexity, the jurisdiction, how many correction cycles the plans go through, inspection scheduling, and material lead times all move the finish date, which is why we give you a six to fourteen month range at the start instead of a single date we cannot hold.

A build that long has a household side, so we plan that too: which weeks are loud, when the site is open, how the utility tie ins are staged, and when you get your routine back. A long project is manageable when you know the sequence. It is miserable when you do not.

Home addition and ADU permit-to-completion timeline Eight sequenced phases across six to fourteen months: design and drawings, plan check and city review, permit issuance, foundation, framing, rough-in and inspections, interior and exterior finishes, final inspection and completion. Plan check is called out as often the longest single phase. Home addition & ADU timeline 6 to 14 months typical, permitting and plan review are often the longest phases 1 2 3 4 5 6 7 8 9 10 11 12 13 M14 1 · Design & drawings 2 · Plan check & city reviewOften longest single phase 3 · Permit issuance 4 · Foundation 5 · Framing 6 · Rough-in & inspections 7 · Interior & exterior finishes 8 · Final inspection & completion Planning City review + inspection On-site construction Plan check is often 2 to 6 months, depending on city and correction cycles. Home addition & ADU timelineHome addition & ADU timeline6 TO 14 MONTHS TYPICAL, PERMITTINGAND PLAN REVIEW ARE OFTEN THELONGEST PHASESDesign & drawingsMonths 1 to 3Plan check & city reviewMonths 3 to 5Often longest single phasePermit issuanceMonth 6FoundationMonths 6 to 7FramingMonths 7 to 8Rough-in & inspectionsMonths 8 to 10Interior & exterior finishesMonths 10 to 12Final inspection & completionMonth 12Plan check is often 2 to 6 months,depending on city and correction cycles.
Scroll or swipe to see the full diagram. Why permits are the schedule on a home addition. Six to fourteen months is the realistic window for a residential addition or ADU, and the permit and plan check window is often the longest single phase. Each phase depends on the city clearing the previous one.

Our full service scope

Each phase of an addition waits on an approval or an inspection, so we plan the work around the process rather than around a wish list. This is the scope we take on, from the first set of drawings to the final sign off.

  • Attached additions: room additions and second story expansions designed to read as part of the existing home.
  • Detached ADUs: ground up ADU and granny flat construction, including the foundation, utilities, setbacks, and required approvals.
  • Design and planning: drawings and plan development arranged through a design professional, or coordination with the architect you already have.
  • Permits and inspections: permit applications, plan check corrections, approvals, and inspection scheduling.
  • Complete construction: foundation and framing we build, with roofing, plumbing, electrical, HVAC, insulation, drywall, and finishes coordinated under one schedule.
  • Utilities and connections: utility coordination for a detached ADU, including the required connections and site work.
  • Exterior integration: roof tie ins, siding, stucco, windows, doors, and exterior finish matched to the existing home.

For reference

Home Additions & ADUs in pictures

Two story room addition under construction with new framing, sheathing, and scaffolding against the existing house
New room addition framed onto the back of a single story house, with roof trusses set and the wall framing exposed

From first call to final walkthrough

A clear process. A better experience.

  1. 01

    Site Consultation

    We visit your home or property, listen to your goals, assess the space, and establish the scope of work.

  2. 02

    Detailed Proposal

    You receive a written scope and a fixed price before any construction begins.

  3. 03

    Expert Coordination

    We coordinate every trade and phase in the proper sequence, with one dedicated point of contact keeping the project moving.

  4. 04

    Final Walkthrough

    We review the completed work with you, address any final details, and make sure everything meets the Real Deal standard before we close the project.

Cities we serve

Real Deal Builders delivers this service across the twenty cities we serve, from the Santa Clarita Valley into the San Fernando Valley. These pages cover the work city by city.

FAQ

Common questions

The questions we hear most often, answered plainly. If your question is not here, call us and we will answer it the same way.

Do you build detached ADUs and granny flats?

Yes. ADU and granny flat construction is a growing part of what we do. We handle everything from the design and permit process through foundation, framing, all trades, and final finishes, so you end up with a complete, permitted unit rather than a partial build you have to finish yourself.

Do you build room additions or just full ADUs?

Both. We build room additions, primary suite additions, second story additions, and full detached ADUs. A room addition uses the existing foundation and roof where possible and ties into the current house. A detached ADU is its own building from the ground up.

How long does a home addition take?

Six to fourteen months is a realistic window for a residential addition or ADU, from first design meeting to final inspection. The permit and plan check window is often the longest single phase, and it varies by city and by how many correction cycles the plans go through.

How long does a detached ADU take?

Plan on the same six to fourteen month window, with plan check as the biggest variable at the front of it. A detached unit carries its own foundation, its own utility connections, and its own inspections, so it lands at the longer end of that range more often than a room addition does. Some cities keep a set of pre approved ADU plans that shorten the review, and we help you decide whether one fits your lot.

Do you handle the permits and plan check?

Yes. We handle the permit application, plan check submittal, corrections back and forth with the city, and inspection scheduling. That is the whole reason you hire a licensed general contractor rather than piecing the project together yourself.

Do we need an architect for a home addition?

For additions and ADUs, usually yes, an architect or a design professional needs to stamp the plans. We work with architects you already have and can recommend ones we have worked with before if you need. Bringing us in during the design phase saves money and time because we can flag constructability issues while they are still cheap to fix on paper.

Can we live in the house during a home addition?

Usually yes. We seal the addition from the existing house during framing and rough in so the interior stays livable, and we plan the utility tie in phases so you are not without water or power. There are always a few days where something is off, and we schedule those in advance so nothing is a surprise.

Does a detached ADU need its own utilities?

Usually yes, its own water and power connections, plus its own inspections. Some cities allow a shared service with a separate meter instead. We confirm what your city allows before the plan is drawn, because the answer changes both the site work and the cost.

How much does a home addition or ADU cost?

Cost is driven by size, foundation and framing complexity, whether the addition adds a second story, the finish level, and how much site work is involved. We price against a specific written scope after the design is far enough along to be real rather than guessed at.

What is the biggest risk on a home addition project?

The two biggest risks are plan check delays and hidden conditions when the existing house is opened for the tie in. We manage plan check actively and we stop and show you anything unexpected in the tie in before we cover it back up, so surprises get priced up front.

Planning a project like this?