CGI Home Additions & ADU Nationwide

CGI Home Additions & ADU: The Los Angeles Owner’s Guide

If you have a CGI home addition or ADU and something on it has failed, you need two things: the right part matched to your structure, and a written price before anyone picks up a tool. We stock and install CGI-compatible components across Los Angeles, with most replacement work running $53,100-$153,400 depending on scope. Most owners discover the problem the way you probably did: a door that no longer closes square, a crack that appeared at a seam, or water where water should not be.

Call (470) 298-9650

Rowan Construction Group is an independent contractor. We are not affiliated with CGI, but we have worked on their structures across Los Angeles County long enough to know what fails, what holds up, and what the fix should cost in writing.

Which CGI Models This Applies To

CGI builds prefabricated and panelized additions, and the compatibility question comes down to which generation of wall panel or roof cassette you have. The older CGI series used 2×4 framing with a 16-inch stud layout and a proprietary corner lock system; the newer lines switched to 2×6 framing at 24 inches on center with a different sill anchor pattern. You can identify your generation by pulling the interior trim at any corner and checking the stud width, or by locating the manufacturer sticker on the header above the main entry door.

For OEM parts, the older corner locks are the hardest to source; CGI moved inventory to the newer series years ago and Los Angeles suppliers that still carry the old locks charge a premium. In most cases, a quality aftermarket equivalent, milled locally to the same profile, performs as well for less. For roof cassettes, the fixing is more straightforward: the cam-lock connectors are off-the-shelf and interchangeable across both generations.

Compatibility gotcha: CGI roof cassettes from the pre-2014 run used a 5/8-inch plywood skin. The current production runs use 3/4-inch. If you patch a 5/8-inch cassette with a 3/4-inch panel, you will create a 1/8-inch ridge that telegraphs through the roofing membrane within a season. You have to shim or plane the patch to match.

Signs Your CGI Home Additions & ADU Is Failing

• Doors that stick at the top corner of the jamb. This is usually the wall panel settling or the corner lock loosening. In Los Angeles, the expansion and contraction from our dry heat to coastal damp cycles works these connections loose over time. The fix is re-squaring the opening and re-torquing or replacing the lock.
• A hairline crack running diagonally from a window corner. That diagonal path is the panel joint shifting. It is not the drywall cracking on its own; it is the panel behind it moving. The cause is usually a sill anchor that has lost tension.
• Moisture staining at the ceiling-to-wall seam. This points to the roof cassette-to-wall connection failing at the flashing detail. CGI cassettes drain through a concealed channel, and when the channel clogs or the sealant breaks down, water travels inward before it shows itself.
• A soft spot on the floor near the exterior wall. Los Angeles gets rain in bursts, and a failed sill gasket lets that water wick under the wall panel. By the time you feel the floor give, the rim joist has been wet for a while.
• You can see daylight at the bottom corner of an exterior wall. This is the sill plate lifting or the anchor pulling out entirely. It is the most serious of the common failures because it means the structure is no longer bearing the way it was designed to.

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Replacement Cost & What’s Included

In Los Angeles, replacement work on a CGI addition or ADU runs $53,100-$153,400 installed. Where you fall in that range depends on how much of the structure has to come apart: a corner lock replacement with re-squaring might sit near the low end, while a full wall panel replacement on an ADU with finish work sits near the top.

The number we give you is written before any work starts, and it stays the number unless you approve a change in writing. Under Clause 1 of the Haven Standard, that is not a courtesy; it is how we have run every job since 2007. The price includes parts, labor, debris removal, and a documented photo record of the work on every visit. Your written warranty comes with the written scope.

DIY or Call Us?

You can check the sticker above the entry door to identify your CGI generation, and you can note where cracks are and whether they change with the season. That information helps us price the job faster. What you should not do is open a wall panel and start loosening anchors. These panels carry roof load, and a panel that is unloaded incorrectly can shift on you.

Grant Rowan trained in framing and structural work at Los Angeles Trade-Technical College, and the work we are most often called back for is this kind: walls that have moved and need to be put back where they belong. Measure twice, say it once, show your work. That is the whole approach. If you have a CGI addition or ADU acting up, call (470) 298-9650 and we will tell you what we think it is and what it will cost, in writing, before anyone touches the building.

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