Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
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Before
AfterCGI Construction in Montclair, CA | Rowan Construction Group Pomona
Independent CGI construction service in Montclair typically runs $45,000-$130,000 for home additions and $90,000-$220,000 for ADU builds, with most projects quoted within 48 hours of site visit. What sets our CGI work apart in Montclair is how we engineer foundations for the city’s reactive alluvial clay soils and Seismic Zone 4 demands before the first aluminum frame goes up. Call Montclair service area experts at (626) 606-1081 to schedule your free written estimate.
Why Montclair Residents Choose Us for CGI Service
We’ve been working with CGI aluminum window systems, greenhouse glazing, and sunroom extrusions since before the 2008 code cycle changed how San Bernardino County inspectors look at slab additions. Grant Rowan, our owner, trained at Los Angeles Trade-Technical College and cut his teeth on the exact kind of post-WWII tract housing that dominates Montclair - single-story, slab-on-grade ranches with original stucco and no cripple walls to speak of. That background matters when you’re deciding whether a CGI conservatory can actually survive on a 1962 foundation.
We carry factory-spec CGI replacement glazing, gaskets, and aluminum extrusions for the 3000 series windows, Majestic and Orangerie greenhouse lines, and Solarium conservatory frames. But we don’t pretend to be manufacturer-authorized - we’re independent, which means our repair-or-replace recommendation is based on what your slab and structure can actually support, not what a warranty department wants to hear. Every quote is written, line-itemed, and delivered before anyone picks up a tool. Under Clause 1 of The Haven Standard, that’s non-negotiable.
Our crews are background-checked and uniformed; a live person answers calls 24/7. Every visit produces a documented photo record, included as standard. And if something’s not done right, our 365-Day Done Right Promise means we make it right - backed by terms you can read, not a handshake in the driveway.
Common CGI Construction Problems We Solve in Montclair
- Aluminum frame separation from rough openings. CGI 3000 series windows and sunroom frames crack their seals as Montclair’s expansive clay soils heave and settle through wet-dry cycles. The original 1950s stucco wasn’t built for the thermal movement of a glass-and-metal addition, and the gap widens every summer when the slab drops on the dry side.
- Greenhouse glazing yellowing and brittle failure. Polycarbonate and acrylic panels on CGI Majestic and Orangerie greenhouses degrade under sustained 105°F+ heat and UV exposure. Come fall, a Santa Ana wind event that wouldn’t register in Claremont can shatter a compromised panel and turn your greenhouse into a liability.
- Conservatory roof-to-wall leaks and hidden water damage. CGI Solarium and Conservatory roofs collect condensation where they meet original stucco walls. The original flashing was never designed for the differential expansion of aluminum and glass against 60-year-old plaster, and by the time you see the stain, the framing behind is soft.
- Patio cover post footing separation. CGI Flat Top and Victorian patio cover anchors pull loose as native alluvial clay shrinks away from unreinforced slabs in dry years, then returns with hydraulic pressure that fractures the concrete. We’ve found posts tilted three degrees off plumb from this cycle alone.
- Slab-addition foundation failure on ADU conversions. Converting a Montclair garage to a CGI-based living space or full ADU without addressing the original slab’s lack of reinforcement is asking for the same cracking that split the driveway. We over-excavate and compact aggregate base well beyond county minimum because we’ve seen what the clay does to footings that barely passed inspection.
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AfterCGI Service in Montclair: What Local Conditions Mean for Your Equipment
In Montclair, adding a CGI sunroom or greenhouse to a 1950s slab-on-grade home often requires over-excavating and compacting aggregate base well beyond what a standard San Bernardino County inspection would flag, because the native alluvial clay will shrink away from the original footing in dry years and return with enough force to crack an unreinforced slab. This means the CGI structure’s foundation must be isolated or deepened to handle that seasonal movement, a step that coastal-influenced cities rarely need at the same intensity. We were called to a 1962 slab-on-grade ranch in the Montclair north side where a CGI greenhouse addition had begun leaking at the base plate and pulling away from the house wall. After trenching along the original footing, we found the slab edge had dropped nearly an inch on the dry side while the greenhouse’s aluminum sill had buckled inward - classic reactive clay movement. We re-leveled the slab with a compacted aggregate base and pier-and-beam support, replaced the buckled CGI sill with a reinforced extrusion, and re-flashed the wall junction with a flexible membrane rated for thermal movement. Measure twice, then we can talk.
CGI Models & Products We Service in Montclair
Our CGI sales & service covers the full product line: Majestic and Orangerie greenhouse series for backyard growing structures; Solarium and Conservatory sunrooms for year-round living space; Flat Top and Victorian patio covers for shade and outdoor rooms; and the CGI 3000 series aluminum windows and door systems. We stock replacement glazing, extruded aluminum sills, and EPDM gaskets locally for Montclair jobs, which means turnaround on most repairs doesn’t depend on a factory warehouse in another state. When a frame is racked beyond straightening, we source factory-spec or better replacement extrusions and give you a straight call: repair and re-anchor if the slab can be stabilized, or full reset on an engineered footing if the movement pattern will just repeat. No warranty pipeline, no runaround - just what the structure actually needs.
CGI Service Pricing in Montclair
Every project gets a flat written price before work starts. Here’s what independent CGI construction and related trades run in the Pomona Valley market:
| Service | Price Range |
|---|---|
| Home Addition | $45,000-$130,000 |
| ADU Construction | $90,000-$220,000 |
| Garage Conversion | $30,000-$80,000 |
| Roof Replacement | $8,000-$20,000 |
| Window Replacement | $4,500-$15,000 |
What drives cost: foundation condition and required remediation, seismic anchoring per San Bernardino County Seismic Zone 4, glazing specification (polycarbonate vs. tempered glass), and whether the original slab can be salvaged or needs engineered replacement. Our written estimate includes a documented photo record of existing conditions, a line-item scope, and a fixed price with no change orders unless you sign one. Bring a competitor’s written quote and we’ll review it line by line at no charge. Call (626) 606-1081 for your free estimate.
Serving Montclair, CA - Our Local Coverage Area
We’re based in the Montclair area and know this community well. Use the map below to see our service coverage - if you’re nearby, we can almost certainly help.
FAQs - CGI Construction in Montclair
Will a CGI sunroom or greenhouse hold up on my 1950s Montclair slab?
Only if the foundation is addressed first. Most Montclair slabs from that era lack reinforcement and sit on expansive alluvial clay that cycles seasonally. We assess slab condition, recommend over-excavation and compacted base where needed, and engineer the CGI footing to isolate or deepen beyond the original. Call (626) 606-1081 for a free site evaluation.
Why does my CGI greenhouse glazing keep cracking in Montclair summers?
Sustained 105°F+ heat and intense UV degrade polycarbonate and acrylic panels, making them brittle. When fall Santa Ana winds hit, compromised panels shatter. We replace with factory-spec glazing rated for inland thermal stress and inspect frame alignment - racked frames from slab movement concentrate stress and accelerate failure. Call (626) 606-1081 for an exact quote; estimates are free.
Can you convert my garage into a CGI-based living space or ADU in Montclair?
Yes - we specialize in garage conversions and full ADU construction using CGI window and door systems, as part of our Kitchen Remodeling in Montclair and broader home renovation services. The existing garage slab almost always needs reinforcement or replacement for habitable use, and Montclair’s clay soils demand deeper footings than a standard storage structure. We handle the full scope: slab, framing, CGI installation, and finish. Call (626) 606-1081 to schedule.
How do you handle CGI sunroom leaks at the house wall?
We strip the original flashing, inspect for hidden water damage in the 1950s stucco substrate, and install a flexible membrane rated for the thermal differential between aluminum framing and original plaster - a process we also apply during our Bathroom Remodeling in Montclair projects. If the slab has dropped, we re-level before re-flashing - otherwise the gap just reopens. Call (626) 606-1081 for a free inspection and written repair scope.
Does Santa Ana wind season affect CGI installations in Montclair?
Yes. Fall and winter Santa Ana events can ground crane operations and stress glazing mid-installation. We schedule exterior work outside peak wind periods and use temporary bracing on incomplete structures. For existing CGI patio covers and greenhouses, we inspect anchor integrity before wind season - loose posts from clay cycling become dangerous quickly. Call (626) 606-1081 to schedule pre-season inspection.
Service Areas Near Montclair
We work across the Pomona Valley and western San Bernardino County, including CGI service in Pomona from the Fairplex corridor through downtown, CGI service in San Dimas along the foothill zone, plus Diamond Bar, Claremont, and Walnut. Each city has its own soil profile and code interpretation, and we price accordingly - no cookie-cutter quotes.
Book Your CGI Service in Montclair Today
Call (626) 606-1081 to schedule your free written estimate. We’ll document existing conditions with photos, deliver a line-item scope and fixed price, and start work only after you’ve reviewed and approved both. Grant Rowan and the crew at Rowan Construction Group Pomona have been building this way since 2007 - 4,000-plus projects, every one with a written price before the first tool came out.
Written by Grant Rowan, Owner at Rowan Construction Group Pomona, serving Montclair since 2007.