Steel casement windows are hinged windows that swing open like a door.
They’re known for their sleek frames, durability, and architectural character.
Whether you’re building modern or restoring historic, they bring that “less frame, more glass” look with serious performance.
Understanding Casement Windows
How Casement Windows Open
Casement windows are hinged on one side and usually open outward using a crank or push handle. Think of a door but in window form.
They’re perfect for catching breezes, maximizing views, and creating wide openings for light and air.
Why Architects and Designers Love Them
Because the sash presses tight against the frame when closed, they’re energy-efficient, secure, and bring in more natural light than sliders or double-hungs.
Add steel into the mix, and you’ve got a game-changer in form and function.
Why Steel for Casement Windows?
Strength Without Bulk
Steel is up to three times stronger than aluminum and many times stronger than wood. That strength means you can have slimmer frames without sacrificing stability.
Narrow Sightlines for More Glass
This is the architect’s dream: more glass, less frame. Steel lets you do that — no bulking up around the edges.
Longevity and Weather Resistance
Optimum’s steel frames are galvanized, powder-coated, and often include a thermal break for insulation. They’re designed to outlast most other materials by decades.
Steel vs. Wood and Aluminum Windows
| Feature | Steel | Wood | Aluminum |
|---|---|---|---|
| Strength | 🟢 Excellent | 🔴 Low | 🟡 Medium |
| Sightlines | 🟢 Ultra Slim | 🔴 Thick | 🟡 Moderate |
| Maintenance | 🟢 Low | 🔴 High | 🟡 Medium |
| Weatherproofing | 🟢 Galvanized/Powder | 🔴 Requires Sealing | 🟡 Anodized |
| Lifespan | 🟢 50+ years | 🔴 15–25 years | 🟡 30–40 years |
Optimum Window: Industry Leader in Steel Casement Windows
Built in the USA, Backed by Decades
Since 1985, Optimum Window has been crafting steel window systems in Ellenville, New York. From classic to contemporary, we’ve helped shape everything from penthouses to heritage buildings.
Made for Architects, Homeowners & Developers
Whether it’s a landmark restoration or a modern masterpiece, our casement windows are trusted nationwide for their structural strength, custom fit, and design flexibility.
Key Optimum Product Lines for Casement Windows
HR4500 & HR4700 – Hot-Rolled Steel Series
These are classics. Built from solid hot-rolled steel, they’re made for bold openings and maximum glass.
- Fully welded frame & sash
- Dual weather-stripping
- Glazing up to 1 1/8”
- Concealed or custom hardware
- Ideal for high-end homes, lofts, and institutional projects
RTS430 – Thermally Broken Steel
This line blends beauty with brains. RTS430 offers:
- Thin sightlines for that elegant steel look
- Thermal break to reduce condensation and improve energy ratings
- Custom glazing from single to triple pane
- U-Values as low as .19, rivaling even top wood windows
| Feature | HR4500/HR4700 | RTS430 |
|---|---|---|
| Thermal Break | ❌ | ✅ |
| Material | Hot-Rolled | Stainless Steel |
| Max Glass Thickness | 1 1/8” | 1 3/8” |
| Application | Historic/Modern | High-Efficiency |
| Sightline Aesthetic | Bold & Classic | Delicate & Clean |
6500 Series – Cold-Rolled, Thermally Broken Excellence
The Flex 6500SB is built for large openings and heritage retrofits.
- NFRC rated, tested to ASTM and AAMA standards
- Dual weather-seals + zinc-rich primer
- Oversized options: Casement up to 42″ x 90″
- Custom powder coat colors + finishes in bronze, stainless, and COR-TEN steel
This is the steel window for when design, scale, and performance all matter.
Bonus: Fire-Rated Casement Windows
FR4700 Series – Safety Without Sacrificing Style
Built for buildings where code and design must coexist.
- UL Certified for 45-minute fire ratings
- Tested to withstand 1600°F plus water impact
- Available with wire glass, ceramic, or clear fire-rated glazing
- Slim profiles + full weather-stripping
| Fire-Rated Feature | FR4700 Series |
|---|---|
| UL Certification | ✅ |
| Rating Range | 45–90 mins |
| Material | Cold-Rolled Steel |
| Finish | Powder-Coated |
| Hardware | White Bronze (standard) |
Customization Options with Optimum
Material Finishes
Choose from:
- Stainless Steel
- Bronze
- COR-TEN
- Cold or hot-rolled steel
Color & Glazing Choices
- RAL Standard + custom color matching
- Dual, triple, or monolithic glazing
- Simulated or true divided lites
Hardware Sets
- Multipoint or single-point locking
- Premium handle sets for modern or traditional builds
Use Cases: Residential, Commercial & Historic
Homeowners: Custom Modern Designs
Want curb appeal that doesn’t fade or frames that can stand up to life? Steel casements check all the boxes.
Developers: High-Performance Facades
Steel brings durability, design continuity, and minimal maintenance — ideal for large-scale projects.
Landmark Projects: Preservation + Performance
From landmarks in NYC to historic townhomes, our steel casements help preserve the past while adding comfort and energy efficiency.
Final Thoughts: Why Steel Casement Windows Make Sense
Steel casement windows don’t just look good — they perform for life.
At Optimum Window, we build them to last, to open with ease, and to meet the demands of any design or code.
Let’s build something strong, slim, and stunning — together.
