CGI Home Additions & ADU Nationwide

CGI Home Additions & ADU: The Sherman Oaks Owner’s Guide

CGI-compatible components for home additions and ADU projects in Sherman Oaks typically run $45,000-$130,000 installed, depending on whether you’re extending an existing structure or building a detached unit from the foundation up. We stock and install CGI framing hardware, window systems, and door assemblies matched to your specific model series, and we carry common CGI-compatible fasteners, flashing kits, and sill plates on our Sherman Oaks trucks. Most homeowners first realize something’s wrong when the addition settles unevenly against the original structure, or when ADU windows start binding in their frames after a few hot San Fernando Valley summers.

Call (213) 221-0788

Which CGI Models This Applies To

CGI’s residential product lines span three distinct series: the Estate Collection (aluminum impact windows and doors, common in post-2015 Sherman Oaks builds), the Sentinel Series (vinyl-framed units with reinforced sashes), and the commercial-grade Targa line occasionally specified for high-end ADUs with oversized openings. The critical compatibility point is the frame depth, Estate Collection frames measure 3¼ inches, Sentinel measures 2⅞ inches, and mixing rough-opening dimensions between series is the most common ordering error we correct in the field.

To identify your series, check the etched marking in the glass corner (Estate shows “CGI-EST,” Sentinel shows “CGI-SEN”) or measure the frame depth with a tape measure at the interior stop. For ADU projects, CGI’s sliding door hardware also varies by weight rating, the Estate 3120 slider uses a stainless steel tandem roller rated at 125 pounds per panel, while the Sentinel 2100 tops out at 85 pounds. We source OEM CGI parts through the manufacturer’s Florida distribution center, though for certain flashing and weep-screed components we use quality aftermarket equivalents from MFM Building Products or DuPont that meet the same Miami-Dade wind-load specifications without the six-week OEM lead time.

Signs Your CGI Home Additions & ADU Is Failing

• Windows stick or jam seasonally. CGI’s aluminum frames expand roughly 1/8 inch per 10 feet of frame under Valley summer heat. When the sill track clogs with construction debris or the weep holes block, that expansion has nowhere to go and the sash binds against the frame. We see this most in south-facing ADU walls above 100°F.
• Water stains at the interior drywall corners. CGI units rely on end-dam flashing integrated with the window frame. If the installer skipped the pan flashing or used non-compatible sealant (silicone instead of CGI-specified polyurethane), water migrates behind the fin and rots the king stud. In Sherman Oaks, this shows up first on additions with shallow roof overhangs.
• Sliding doors develop a visible sag or diagonal crack in the drywall above. The tandem roller assembly wears unevenly when the concrete pad settles, which it does in our area’s expansive clay soils. The door frame twists, the latch misses the strike, and the header above takes the load until something cracks.
• Condensation between panes on impact-rated units. CGI’s laminated impact glass uses a polyvinyl butyral interlayer that can delaminate at the edge if the unit sat in direct sun before installation. Once the seal fails, desiccant saturation follows, and the glass fogs permanently. This is a full-unit replacement, not a field repair.
• Exterior trim pulls away from the frame, revealing gaps. CGI specifies a ⅜-inch expansion gap at the perimeter, covered with backer rod and sealant. When painters or subsequent contractors caulk that gap solid, the frame pushes against rigid sealant and the trim board bows outward. It’s cosmetic until water gets behind it.

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Replacement Cost & What’s Included

The wide range on full projects reflects three variables: whether the addition ties into existing structural walls or stands independent, the soil condition after our geotechnical review, and the finish level specified. Under Clause 1 of the Haven Standard, the price we write is the price you pay, no change proceeds without a signed change order, and our documented photo record shows every layer before it’s covered. The 365-Day Done Right Promise covers labor and installation, CGI’s factory warranty covers the product itself.

DIY or Call Us?

There’s a safe middle ground here. An owner can verify the model marking, measure frame depth, and clear weep holes with a piece of wire, no special tools needed. What goes wrong fast: removing a CGI impact window without temporary bracing exposes the opening to wind load, and Sherman Oaks sits in a design wind zone where an unbraced opening can rack the framing in a Santa Ana event. Sliding door rollers carry the full panel weight, 80 to 150 pounds, and the adjustment screws sit under tension, one slip and the panel drops on your hand.

We don’t recommend DIY on any component that carries structural or weather-protection duty. Call (213) 221-0788 and we’ll schedule a free estimate with a written line-item quote before any work starts. Our crews carry CGI-compatible parts on the truck for same-day resolution when the job scope allows.

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