Free written scope consultation - allowances, timeline, and change-order rules on paper before a single trade is scheduled
CWS Construction in Los Altos, CA | Rowan Construction Group Cupertino
We provide independent CWS window and door service across Los Altos - not as an authorized dealer, but as a construction contractor that has installed and repaired CWS products on hundreds of residential projects since 2007. The one thing that sets our CWS work apart here is our familiarity with Los Altos’s Architectural and Site Review process: we know not to order a single CWS unit until the ASR-approved plans are in hand, because massing revisions after sign-off are expensive and common. Call (669) 202-9618 to schedule your free estimate.
Why Los Altos Residents Choose Us for CWS Service
We’ve worked CWS products through the full cycle of Los Altos construction - from replacing failed vinyl frames in 1960s ranch homes to specifying Series 7000 aluminum-clad wood windows for new custom builds on Foothill Road parcels. Grant Rowan, who leads our crew, grew up watching hillside framing off Coldwater Canyon and trained at Los Angeles Trade-Technical College before moving north to build in Santa Clara County. He’s spent more than a decade working Cupertino and Los Altos, including gut renovations in Monta Vista, and he brings the same documentation habit to every CWS job: written scope, materials list with named brands and line-item costs, phased timeline you can follow week by week. CWS sales & service from our team means OEM-compatible parts when we can get them, honest repair-vs-replace guidance when we can’t, and a photo record of every visit included as standard - not an upgrade.
Our independence matters. We’re not pushing CWS inventory out of a regional warehouse. We source what’s right for your opening, your exposure, and your ASR-approved plans. Under Clause 1 of the Haven Standard, the price is written before anyone starts. No exceptions.
Common CWS Construction Problems We Solve in Los Altos

- Non-standard rough openings on post-and-beam ranch homes. The 1952-1972 stock throughout Los Altos was framed with dimensional lumber that doesn’t match modern CWS unit sizes. We regularly find openings out-of-square by 3/8-inch or more. Without proper shimming and integrated flashing, CWS windows leak air and water within two to three years - we’ve torn out plenty of “professional” installs that skipped this step.
- Aluminum-clad wood rot at the sill. Los Altos sits far enough inland to run hot and dry from June through September, then concentrates its entire annual rainfall into November through April. That wet-dry cycle is hard on CWS Series 7000 cladding seams and end dams. Water gets behind the aluminum, sits against the wood sill, and rots it from the inside out. We catch this during pre-purchase inspections on homes along Magdalena Avenue and similar neighborhoods.
- Vinyl frame distortion on south and west elevations. Los Altos’s inland summers run 10-15 degrees warmer than coastal Santa Clara County. CWS Series 4000 vinyl windows on full-sun exposures experience thermal expansion stress that distorts frames and breaks seals. We’ve replaced units on Loyola Corners ranches where the glass was fogged and the sash wouldn’t operate after eight years.
- Sliding door track failure from dry-season grit. CWS Series 5000 sliding glass doors collect Los Altos’s summer dust, pollen, and fine granitic soil in their tracks. Rollers wear flat. Panels bind. Homeowners call thinking it’s a glass or frame problem; usually it’s a $200 roller and track cleaning, not a full door replacement. We stock the common CWS roller sizes for same-visit fixes when possible.
- Electrical and structural surprises during window replacement. Los Altos ranch homes still carry knob-and-tube-era panels and original cast-iron drain lines. Opening a wall for a larger CWS unit or a new sliding door location regularly reveals subpanels that won’t handle added circuits or framing that needs sistering. We quote this discovery risk upfront, document what we find with photos, and never proceed on a change without a signed change order.
Before
AfterCWS Service in Los Altos: What Local Conditions Mean for Your Equipment
Los Altos’s Architectural and Site Review process is the single most important local factor for any CWS window or door package on a new custom build or substantial alteration. Unlike neighboring Sunnyvale or Santa Clara, where permitting is more streamlined and commercially oriented, Los Altos requires design approval that scrutinizes massing, rooflines, and neighborhood compatibility before a permit application is even accepted. This adds two to four months. Contractors who order CWS units against preliminary plans - a temptation when lead times are long - routinely face expensive change orders when ASR revisions alter rough opening dimensions or eliminate a planned clerestory bank. We specify and order only against approved ASR sets. On a 1964 post-and-beam ranch in the Loyola Corners area of Los Altos, we replaced seven failed CWS Series 7000 aluminum-clad wood windows as part of our Kitchen Remodeling in Los Altos that had been leaking at the sill for years, causing rot in the original redwood framing. After ASR-approved plans were in hand, we reframed the rough openings, flashed and sealed the new CWS units, and matched the interior trim to the home’s original clear-heart redwood - the owner passed final inspection with no change orders. That’s the discipline Haven acquired Rowan for, and it’s what keeps projects within a few percent of the agreed number.
CWS Models & Products We Service in Los Altos

We work across the residential CWS product line most common in Los Altos custom builds and renovations: Los Altos service area coverage includes the Series 7000 Aluminum-Clad Wood Windows (the high-end standard for new construction matching mid-century ranch scale), Series 4000 Vinyl Windows (cost-effective replacement on secondary elevations), Series 5000 Sliding Glass Doors (standard for backyard indoor-outdoor flow on 8,000-14,000 sq ft parcels), and Custom Wood Entry Door Systems (specified against ASR-mandated neighborhood compatibility requirements). We stock OEM CWS replacement parts - sash balances, rollers, weatherstrip, glazing beads - for faster turnaround on Los Altos service calls. When OEM is discontinued or lead times threaten a schedule, we use high-quality aftermarket equivalents and document the substitution in writing. For CWS windows and doors older than 20 years with rot or failed seals, we give an honest repair-vs-replace comparison: repair for isolated hardware or glass; full replacement when frames or cladding are compromised. Measure twice, document once, explain it plainly.
CWS Service Pricing in Los Altos
Every CWS project in Los Altos gets a flat written price with line-item scope before work starts. No “call for a quote” - that contradicts Clause 1 of the Haven Standard. Here’s what our CWS work runs in this market:
| Service | Price Range |
|---|---|
| Window Replacement (per project) | $4,500-$15,000 |
| Impact Window Installation (per project) | $8,000-$25,000 |
| Home Addition (per project) | $45,000-$130,000 |
What drives cost: unit count, opening condition (non-standard rough openings require reframing), exterior access (scaffolding on hillside Los Altos parcels), and whether ASR-approved plans are finalized. Our free estimate includes a written scope, materials list with named brands, phased timeline, and photo documentation of existing conditions. Bring a competitor’s written estimate and we’ll review it line by line at no charge. Call (669) 202-9618 to schedule.
Serving Los Altos, CA - Our Local Coverage Area

We’re based in the Los Altos 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 - CWS Construction in Los Altos
No. We specify and order CWS units only against ASR-approved plans. Ordering against preliminary drawings in Los Altos regularly produces expensive change orders when massing or roofline revisions alter rough opening dimensions. The two-to-four-month ASR timeline is non-negotiable, and we build our procurement schedule around it. Call (669) 202-9618 to discuss timing for your project.
Yes, with proper installation. The Series 7000 performs well in Los Altos’s dry, warm summers and concentrated winter rains when the cladding seams, end dams, and sill pan flashing are detailed correctly. The failure mode we see is water getting behind poorly sealed cladding, not the product itself. Our crews flash and seal to the CWS installation manual plus our own field protocols developed on local ranch homes.
A full-house replacement on a 1,200-1,800 sq ft single-story ranch runs five to eight working days, assuming standard rough openings and no structural surprises. Non-standard openings from the 1952-1972 construction era add reframing time. We provide a phased timeline with your written quote so you know which rooms are open each day.
We repair tracks and rollers whenever possible. Most CWS Series 5000 binding issues in Los Altos are caused by grit accumulation and worn rollers, not frame or glass failure. A track cleaning, roller replacement, and alignment adjustment runs a fraction of full door replacement. We stock common CWS roller sizes for faster turnaround. When the frame is distorted or the glass seal has failed, we’ll give you an honest repair-vs-replace comparison with numbers in writing.
Yes. The CWS Series 7000 aluminum-clad wood window and Custom Wood Entry Door Systems can be specified with divided-lite patterns, interior wood species, and exterior cladding colors that complement mid-century ranch proportions. On our Loyola Corners project, we matched clear-heart redwood interior trim to the home’s original 1964 woodwork. We photograph existing conditions, provide sample mock-ups where ASR requires neighborhood compatibility review, and document every detail in the written scope before ordering, just as we do on every Los Altos Bathroom Remodeling project.
Service Areas Near Los Altos

We serve Los Altos and surrounding Santa Clara County communities from our Cupertino base. Our crews work regularly in CWS service in Cupertino (including Monta Vista and Rancho Rinconada), CWS service in Saratoga (foothill custom builds with similar ASR considerations), plus Sunnyvale, Santa Clara, and Campbell. Each market has its own permitting rhythm and housing stock; we adjust our documentation and scheduling accordingly.
Book Your CWS Service in Los Altos Today
Call (669) 202-9618 to schedule your free CWS estimate in Los Altos. We’ll review your existing windows or doors, photograph conditions, and deliver a written price with line-item scope before any work starts. That’s Clause 1 of the Haven Standard, and it’s how we’ve kept 4,000-plus projects within a few percent of the agreed number since 2007.
Written by Grant Rowan, Owner at Rowan Construction Group Cupertino, serving Los Altos since 2007.







Before
After
Before
After
Before
After