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When it comes to window installation in St. Louis, most homeowners focus on the product—which brand, which style, which glass. But even the best window on the market will underperform if the installation falls short. That’s why Forshaw manages the entire process from start to finish: one company, one bill, one point of contact.

We’ve been a family-owned St. Louis business since 1871. Five generations of quality standards, applied now to the window and door market—because your installation deserves the same level of care and accountability as every other part of the project.

☎ (314) 993-5570   |   Schedule a Free Consultation   |   Get a Free Quote

Why Window Installation Quality Matters More Than You Think

Homeowners spend weeks researching brands, comparing specs, and choosing the perfect window. Then the installation gets handed off to a crew they’ve never met, working for a company they didn’t hire. That’s how the St. Louis window market typically works—and it’s a problem.

Poor installation leads to air leaks, water infiltration, condensation between panes, difficulty opening and closing, and premature seal failure. These aren’t cosmetic issues. They affect your energy bills, your comfort, and eventually your wallet when the window needs to be re-done.

That’s why professional window installation isn’t a nice-to-have. It’s the single most important factor in whether your new windows perform the way the manufacturer intended.

Forshaw’s Approach to Window Installation

In the St. Louis market, most window contractors operate the same way: sell the windows, then send a subcontractor crew to handle the installation. You chose the company, but a different team shows up at your door. If something goes wrong, you’re caught between two parties pointing fingers.

Forshaw window replacement service is building this business differently. Our goal—and the standard we hold ourselves to—is full accountability over every phase of your project.

One Company, One Bill, One Call

When you work with Forshaw, you’re not juggling a sales company and a separate install crew with conflicting timelines. We manage the entire process from consultation through final walkthrough. If there’s ever a question or concern, you call one number: ours. That level of accountability is rare in this market, and we think it’s the way the industry should work.

High Standards for Every Installation

We hold every installation to the same quality standards that have defined Forshaw for over 150 years. That means proper measurement, proper fit, and proper attention to detail—because a window that isn’t installed correctly is a window that won’t perform the way it should. As a Marvin dealer, we follow Marvin’s installation guidelines, which helps ensure your warranty is fully supported.

We Sell What We Stand Behind

Because Forshaw is both the dealer and the company managing your installation, there’s no gap between what gets promised in the showroom and what gets delivered at your home. The same company that walks you through product options is the one that’s accountable for how those products get put in.

Questions about how we handle installation? Call (314) 993-5570 or schedule a free consultation.

What We Install: The Marvin Window Lineup

Forshaw is a Marvin dealer, which means our window installers work exclusively with Marvin products. That focus matters—rather than juggling a dozen brands with different specs and installation requirements, our teams develop deep familiarity with the Marvin lineup.

Collection	Ideal For	Installation Considerations
Ultimate	Historic homes, luxury renovations, and projects requiring maximum customization	Custom sizing and true divided lights mean precise measurement is critical. Often best suited for full-frame installation. Available with extruded aluminum or wood exteriors and a 20-year factory finish.
Elevate	Homeowners who want fiberglass durability with the warmth of a real wood interior	Ultrex fiberglass exterior is dimensionally stable across temperature extremes—an important trait for St. Louis’s climate. Works for both full-frame and insert applications.
Modern	Contemporary architecture, oversized openings, and smart-home integration	Large-format panels and narrow sightlines may require structural assessment. Connected Home automation features (voice control, rain detection) need coordination with electrical.
Essential	Budget-conscious projects that still demand durability and Marvin’s build quality	Full fiberglass construction (eight times stronger than vinyl) with a streamlined selection of popular sizes. Straightforward installation with fewer custom variables.

Not sure which collection fits your project? Visit our St. Louis showroom to see and operate Marvin windows side by side, or schedule a consultation and we’ll help you work through the options.

Full-Frame vs. Insert: Two Approaches to Window Installation

Every new window installation starts with a fundamental question: does your home need a full-frame installation or an insert? The answer depends on the condition of your existing window frames—and it has a major impact on both the quality of the result and the cost of the project.

Insert Installation

An insert places a new window unit inside the existing frame. It’s faster and less invasive, and it works well when the surrounding frame is structurally sound. The tradeoff is that inserts don’t address underlying frame issues—rot, failed flashing, or gaps in insulation stay hidden behind the new unit.

Full-Frame Installation

A full-frame installation removes everything—sash, frame, trim, and all—down to the rough opening. New flashing, insulation, and a complete window system go in. It’s more involved, but it addresses the problems that inserts leave untouched.

Decades of Midwest temperature swings, moisture, and settling take a toll on original frames that isn’t always visible from the inside. We handle both the full-frame and insert approaches and price both options for most projects so you can make an informed comparison.

How Window Installation Works with Forshaw

From the first phone call to the final walkthrough, here’s what you can expect when you work with Forshaw as your window contractors in St. Louis:

1. Free In-Home Consultation

We visit your home to evaluate your current windows, assess frame conditions, take measurements, and understand your goals—whether that’s energy efficiency, curb appeal, noise reduction, or all of the above. We recommend insert or full-frame based on what your home actually needs, not what’s fastest to sell.

2. Product Selection

We invite you to our St. Louis showroom to see Marvin windows in person—open and close them, compare finishes, and take your time. No clock running, no pressure to decide on the spot.

3. Transparent Quote

We provide a detailed estimate that breaks down product costs, installation, and any structural work. When both insert and full-frame are viable, we price both so you can compare. No hidden fees. No “sign-tonight” discounts that evaporate tomorrow.

4. Installation

We manage the installation process to Forshaw’s standards—proper measurement, proper fit, proper weatherproofing. Because we’re accountable for both the product and the installation, there’s no gap between what was promised and what gets delivered.

5. Final Walkthrough

We walk through every installed window with you before considering the job complete. We make sure everything operates correctly, answer any questions, and confirm you’re satisfied. Your new Marvin windows are backed by one of the strongest warranties in the industry.

Ready to get started? Call (314) 993-5570 or request your free estimate online.

Signs Your St. Louis Home Needs New Windows

Not sure whether it’s time for new window installation? Here are the signs St. Louis homeowners most commonly notice before scheduling window replacement:

Drafts and Air Leaks

If you feel cold air near your windows in winter—even when they’re closed and locked—the seals or frames have likely failed. This is especially common in homes built during the 1980s and 1990s when vinyl windows with shorter lifespans were standard.

Condensation Between Panes

Fog or moisture trapped between glass panes means the insulating seal has broken. The window’s energy performance is significantly compromised, and no amount of cleaning will fix it.

Difficulty Opening or Closing

Windows that stick, jam, or won’t stay open are more than an inconvenience—they’re a safety concern. Frame settling, warping, and failed hardware all contribute. In many cases, the frame itself needs replacement, not just the sash.

Visible Rot or Water Damage

Soft spots in wooden frames, peeling paint that keeps coming back, or water staining around the window are signs that moisture has gotten behind the unit. An insert won’t solve this—full-frame installation is typically the right call.

Rising Energy Bills

If your heating and cooling costs keep climbing despite no change in usage, your windows may be a significant factor. Modern Marvin windows with low-E glass and insulating frames can make a real difference—particularly through St. Louis’s extreme summers and winters.

Window Installation Across the St. Louis Metro

Forshaw serves homeowners throughout the St. Louis metropolitan area. Every neighborhood has its own housing stock and its own installation challenges:

Kirkwood & Webster Groves: Older homes with original wood-frame windows that have weathered decades of Missouri seasons. Many benefit from full-frame installation to address underlying rot and settling.

Chesterfield & Ballwin: A mix of housing ages. Newer Ballwin homes were often built with budget-grade windows during periods of rapid development, which means they sometimes need replacement sooner than homeowners expect. Chesterfield’s larger homes frequently involve multi-story projects.

Clayton & Ladue: Historic districts and luxury properties that may require Marvin’s Ultimate collection for period-appropriate detailing, true divided lights, and historic commission approval.

St. Charles & St. Peters: Growing communities with strong demand for both new construction and replacement work in aging subdivisions.

We also serve Frontenac, Wildwood, Des Peres, Town and Country, University City, and surrounding communities.

About Forshaw of St. Louis

Forshaw has been a family-owned St. Louis business since 1871—five generations of serving this community with quality products and honest service. We built our reputation in hearth and outdoor living, and we’re bringing that same standard of care to the window and door market.

As a Marvin dealer, we offer product expertise, transparent pricing, and a showroom experience designed around a simple idea: you deserve to know exactly what you’re getting and exactly what you’re paying for, with one company accountable for all of it.

Talk to our team: (314) 993-5570  |  Schedule a Free Consultation  |  Get a Free Quote

Frequently Asked Questions About Window Installation in St. Louis

Q: How do I choose the right window installer in St. Louis? Look for a company that manages the full process—product selection through installation—rather than handing off the install to a separate crew. Ask whether they provide a detailed written quote, carry proper licensing and insurance, and work with a reputable window brand. At Forshaw, we manage the entire project and are accountable for both the product and the installation.

Q: How long does window installation take? For a typical St. Louis home, installation takes anywhere from one day to two weeks depending on the number of windows and complexity of the work. Full-frame installations take longer than inserts because they involve removing and rebuilding the entire window opening. We provide a clear timeline before any work begins.

Q: Can you install windows in older St. Louis homes? Yes. Many of our projects involve older homes in neighborhoods like Kirkwood, Webster Groves, Clayton, and Ladue. Marvin’s Ultimate collection is well-suited for these homes, offering true divided lights, custom sizing, and designs that meet historic district requirements.

Q: What’s the difference between full-frame and insert installation? An insert places a new window inside the existing frame. Full-frame installation removes the entire assembly—frame, trim, and all—down to the rough opening and installs a complete new system. Most St. Louis homes, particularly those built before the mid-2000s, benefit from full-frame because the original frames have endured decades of extreme weather. Forshaw prices both options so you can compare.

Q: Does Forshaw handle new construction window installation? Yes. While much of our work involves replacement and renovation projects, we also work with builders and architects on new construction. Our focus on Marvin products makes us a strong partner for custom home projects in the St. Louis area.

Q: Will new windows lower my energy bills? In many cases, yes. Modern Marvin windows feature low-E glass coatings, insulating gas fills, and advanced frame materials that significantly outperform the single-pane or early double-pane windows found in many St. Louis homes. The difference is often noticeable in the first heating or cooling season after installation.

Q: What areas does Forshaw serve? We serve homeowners throughout the St. Louis metropolitan area, including Chesterfield, Kirkwood, Webster Groves, Clayton, Ladue, Ballwin, St. Charles, St. Peters, Frontenac, Wildwood, Des Peres, Town and Country, University City, and surrounding communities.

☎ (314) 993-5570   |   Schedule a Free Consultation   |   Get a Free Quote

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