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CGI Home Additions & ADU: The Los Angeles Owner’s Guide
A full CGI-style home addition or ADU project in Los Angeles typically runs $53,100 to $153,400 when built by a licensed general contractor, with garage conversions landing between $35,400 and $94,400. We install complete addition and ADU projects built around CGI-compatible structural components, which covers the framing lumber package, sheathing, ties, and hardware. Most homeowners realize a component has failed not during construction, but months later, when a settling foundation crack opens at a corner seam, or a subfloor starts deflecting underfoot in the new room.
The reality in Los Angeles is that our soil, expansive clay in pockets from the Valley down through Mid-City, plus the occasional seismic event, punishes structural connections that were under-specified or improperly fastened. That’s where we come in.
Which CGI Models This Applies To
Here’s the part most people don’t expect: CGI, in the home additions and ADU context, usually refers to Computer Generated Imaging specifications in the architectural plan set, not a physical hardware brand. Homeowners come to us holding plans rendered in CGI software, or they’ve bought a pre-designed ADU package that references CGI structural standards for shear walls, hold-downs, and framing schedules. What they actually need matched is the physical component: Simpson Strong-Tie connectors, USP structural screws, engineered lumber (LVL or glulam beams), and anchor bolt assemblies specified in those drawings.
So the “right part” depends on the plan set. We pull the structural schedule, match each connector to the exact model number on the sheet, and flag anything that doesn’t meet current Los Angeles Department of Building and Safety code. If your plans call for a specific shear wall nailing pattern and the original builder used the wrong clips at the sill plate, that’s the compatibility gotcha we catch before it becomes a foundation crack. You don’t need to know the part number. You need someone who reads plans without guessing, which is what we do.
Styles & brands we work with
Signs Your CGI Home Additions & ADU Is Failing
- Cracks at wall-to-ceiling seams in the addition. This usually means the roof diaphragm wasn’t properly tied to the new walls, and seasonal expansion in Los Angeles heat is pulling the joint apart. The fix is structural, not caulk.
- Doors or windows sticking in the new space. When the foundation settles unevenly, the rough openings shift. A door that binds in summer but frees up in winter is a telltale sign the sill plate wasn’t anchored to code.
- Floor bounce or squeaking you didn’t have before. Undersized joists or missing blocking cause deflection. In an ADU over a garage, this often traces back to the original beam span being exceeded.
- Drywall cracking in a stair-step pattern. That’s shear movement. The wall is racking because the hold-downs at the corners are loose, missing, or the wrong spec for the seismic zone.
- Separation between the old house and the new addition. In Los Angeles, we build additions with a deliberate movement joint where they meet the original structure. When that gap opens wider or closes up, something underneath is moving more than it should.
See the difference
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After
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AfterReplacement Cost & What’s Included
For a full home addition in Los Angeles, you’re looking at $53,100 on the low end for a modest bump-out or extra bedroom, up to $153,400 for a large two-story addition with structural upgrades. ADU construction runs higher, $106,200 to $259,600, because it includes separate utilities, a kitchen, and its own foundation system. Garage conversions span $35,400 to $94,400 depending on whether the existing slab needs reinforcement and how much plumbing has to be trenched.
Every quote we write is a line-item price before any work starts. You’ll see the structural hardware separated out, the lumber package broken down, the labor hours estimated, and the permit fees listed. If the number changes, you’ll know why, in writing, before we touch the wall. And the 365-Day Done Right Promise covers the entire project from the day we close out: if something fails in the first year because we installed it wrong, we fix it on our dime.
DIY or Call Us?
This is not a spring you replace in a garage door and move on with your Saturday. Home addition and ADU structural work in Los Angeles requires permits, engineering sign-off, and inspections. Doing it wrong means you’re sitting in a room that’s not legal, not insured, and potentially not safe in the next earthquake. We’ll say it plain: anything that involves cutting into load-bearing walls, tying new framing to existing rafters, or altering the foundation is not a DIY job.
What you can safely check: grab a flashlight and look at the crawlspace or the exposed framing in the garage. Look for split plates, rusted connectors, or daylight where the sill meets the concrete. Write down what you see, take photos, and call us. Luca Romano spent his teenage years watching his uncle gut a Silver Lake duplex, and the lesson stuck: the guy who knows when to stop swinging the hammer is the guy whose work holds up. Call (254) 272-5876 and we’ll send someone who introduces themselves before they walk in.
FAQs
How long should a home addition or ADU last in Los Angeles?
A properly built addition or ADU should last as long as the original house, 50+ years. In Los Angeles, the weak points are connections exposed to seasonal clay-soil movement and seismic forces, which is why we spec connectors and hold-downs that exceed minimum code, not just meet it. Call (254) 272-5876 if you want a structural review of your existing addition.
Can a failing addition component be repaired instead of replaced?
Yes, in many cases. Loose hold-downs can be re-torqued, missing blocking can be added through an access panel, and undersized beams can be sistered or supplemented without tearing the whole thing down. The repair decision depends on whether the original work was installed to the plan spec at all. Call (254) 272-5876 for an inspection, and we’ll tell you if it’s a patch or a redo.
How long does a structural repair or addition correction take?
A typical structural correction runs three to seven working days, depending on the extent of the demolition needed to access the failing area and whether the city inspector needs to re-sign off. For a full addition or ADU build, you’re looking at three to six months. We give you a written schedule with the quote, and you’ll see photo updates at every stage. Call (254) 272-5876 for a timeline specific to your project.
Do you stock the structural hardware, or do I need to order it?
We stock common Simpson Strong-Tie connectors, anchor bolts, structural screws, and framing fasteners on our trucks, and we source engineered lumber and specialty hardware locally in Los Angeles, often same-week. For CGI-specified components with long lead times, we order the day you sign the contract so materials aren’t holding up the job. Call (254) 272-5876 to confirm your part spec and availability.
Written by Luca Romano, Owner, Sawyer Remodeling at Sawyer Remodeling, serving Los Angeles and nearby areas.
