Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
CGI Home Additions & ADU: The Thousand Oaks Owner’s Guide
We install and build CGI home additions and ADUs in Thousand Oaks, with typical project costs running between $45,000 and $130,000 depending on square footage, foundation work, and finish level. Most homeowners call us after discovering their existing addition has a structural or systems failure: a cracked foundation seam, water intrusion at the roofline, or electrical that was never permitted. You’ll get a written price before any work starts, and every crew member who comes to your door is background-checked and introduced by name and photo before they arrive.
Here’s the honest picture: a home addition or ADU is not a single “part” that fails. It’s an assembly of systems, and when one goes wrong, it takes others with it. In Thousand Oaks, with our hot dry summers and winter rain cycles, we see the same failure patterns repeat. The good news is most of them are fixable without tearing the whole structure down.
Which CGI Models This Applies To
CGI is best known in California for impact-rated windows and doors, and if your Thousand Oaks home addition or ADU was built with CGI products, you’re working with some of the strongest aluminum-framed fenestration on the market. The most common CGI lines we service are the Estate Collection, Sentinel Series, and the Targa line for multi-slide doors. Where owners get tripped up: the glass package matters as much as the frame. A CGI window rated for Miami-Dade wind loads is not automatically the same glass package as one rated for Ventura County fire zones, so the label matters.
You’ll find the identifying label on the edge of the sash or the head of the frame, usually a silver or white sticker with the series code and impact rating. If that label is gone, we can match by measuring the visible glass and frame depth. On the OEM versus aftermarket question: for CGI glass, we recommend OEM or matched equivalent. Mixing aftermarket glass into a CGI impact frame can void the pressure-rating, and in Thousand Oaks, where Santa Ana winds hit hard against the hillsides near Lang Ranch and Westlake, that rating is not paperwork. It’s the difference between a window that holds and one that doesn’t.
Styles & brands we work with
Signs Your CGI Home Additions & ADU Is Failing
- Fog or condensation between the glass panes. The seal has failed and the inert gas fill has escaped. The window still looks fine from inside the room, but the insulating value is gone, and so is the impact rating on that unit.
- Difficulty sliding or locking multi-slide doors. We see this constantly in ADUs built on post-tension slabs. The slab settles a quarter inch, the track binds, and suddenly a door that closed smoothly for years needs muscle. That’s not normal wear; that’s movement under the frame.
- Water staining at the bottom corners of windows or door thresholds. In Thousand Oaks, the winter rains find every installation flaw. A stain that appears during a storm and fades afterward points to a flashing or weep hole problem, not a leak in the wall itself.
- Cracking at the seam where the addition meets the original house. Different foundations move at different rates. A hairline crack is often cosmetic, but a crack that widens or steps is structural and worth a look before it becomes a bigger fix.
- Warped or bowed exterior door frames. Direct sun exposure on the south and west sides of Thousand Oaks homes bakes aluminum frames. If the frame bows, the door will not seal, and the problem compounds with every season.
See the difference
Before
After
Before
After
Before
AfterReplacement Cost & What’s Included
For a full home addition or ADU project in Thousand Oaks, you’re looking at $45,000 to $130,000. A garage conversion runs $30,000 to $80,000. If you’re replacing failed CGI windows or doors within an existing addition, that work typically falls between $4,500 and $15,000 depending on how many openings and which series you’re matching. The range is driven by three things: foundation condition, whether the existing framing is sound, and finish level.
Every price we give is written, line-item, and delivered before work starts. No verbal estimates that drift upward, no change orders unless you ask for something different. The price includes materials, labor, permits where required, and disposal. Every project is covered by our 365-Day Done Right Promise: if the work is not right within a year of completion, we make it right at no cost to you.
DIY or Call Us?
What you can safely check yourself: visible cracks, water stains, door and window operation, and the condition of weatherstripping. Write down what you see, when you see it, and take photos. That saves time when you call.
What you should not attempt: structural repairs, moving load-bearing walls, electrical work requiring permits, or anything involving impact-rated glass. A CGI window unit weighs more than you think, and trying to remove one without proper support is how people get hurt. We’ve also seen homeowners “patch” a foundation crack with sealant and make the underlying problem worse. If you’re not sure, call us at (805) 309-3386. We’ll tell you over the phone whether it’s worth a service visit, and that consult doesn’t cost you anything.
FAQs
CGI aluminum frames typically last 25 to 35 years in our climate, but the glass seals usually need replacement around the 12 to 18 year mark. Direct sun exposure on south-facing walls shortens that timeline. Call (805) 309-3386 if you’re seeing fogging or condensation between panes; we’ll assess whether you need glass replacement or frame work.
Most failures we see in Thousand Oaks are repairable without demolition. Foundation cracks can be stabilized, water intrusion can be resolved with proper flashing and weep systems, and bad electrical can be brought up to code. Full rebuilds only make sense when the framing itself is compromised. We’ll tell you which one you’re dealing with honestly. Call (805) 309-3386 for an assessment.
A garage conversion typically takes 8 to 12 weeks. A ground-up ADU runs 4 to 6 months. A full home addition of significant square footage can take 6 to 10 months from permit to final inspection. The schedule depends on permitting at the City of Thousand Oaks and Ventura County, and on what inspections are required for your specific site. You’ll have a written timeline before we start, and we hit it. Call (805) 309-3386 if you want a realistic schedule for your specific project.
We keep common CGI hardware, weatherstripping, and lock sets on our service trucks, and we can source CGI glass and frames through our supplier network quickly, usually within 5 to 10 business days. For full addition and ADU projects, we order materials as soon as the written price is approved so nothing sits idle. Call (805) 309-3386 and tell us what you need; we’ll check availability while you’re on the phone.
Tell me what you need done. We’ll tell you what it costs and how long it takes, then we’ll do exactly that.
We also work with KraftMaid, Cambria, and Silestone products for kitchen, bath, and interior finish work on additions and ADUs. Mason Remodeling Co Thousand Oaks is an independent service provider and is not affiliated with CGI.
Call (805) 309-3386 to schedule your free estimate. We serve Thousand Oaks and the surrounding areas, and a live person answers every call, 24/7.
Written by Isaac Pruett, Owner, Mason Remodeling Co – Thousand Oaks, CA at Mason Remodeling Co Thousand Oaks, serving Thousand Oaks and nearby areas.
