Landmark Windows Meet High Performance

Common Questions for High Performance Windows

When most people hear Landmark Windows, they think historic, and historic doesn’t always sound like high performance. We often get questions about whether landmark-approved windows can truly meet today’s standards. To clear up some of the most common misconceptions, our team put together answers to the questions we hear most often.

Are Landmark Windows Still ENERGY STAR® Certified?

Yes. Many people are surprised to learn that Landmark Windows can be built to meet ENERGY STAR® certification. By using modern glazing, thermal breaks, and low-E coatings, they offer insulation and efficiency comparable to today’s top-performing windows, while still keeping the historic look that’s required for landmarked buildings.

How Do Landmark Windows Compare to Newer High-Performance Brands?

It’s a fair question — newer brands market themselves heavily on performance. What we’ve seen in our projects is that Landmark Windows hold their own. They meet the same performance ratings for insulation and sound as modern competitors, but with the added benefit of being custom-built to match historic detailing. That’s something you won’t find in a mass-produced window.

At 214 West 16th Street, we installed period-correct Norwood NorClad double-hung windows approved by the Landmarks Commission. Norwood’s data for this line shows U-factors in the 0.27–0.33 range with standard double-pane builds, and even lower with higher-performance options. In practice, these windows delivered the same efficiency as modern high-end brands, with the added benefit of historic accuracy.

Do Landmark Windows Still Meet 2025 Energy Efficiency Standards?

Yes. As codes tighten, Landmark Windows can be specified with the upgrades needed, from insulated glass units to gas fills and thermally broken frames, to stay ahead of the requirements. We work with these options regularly to ensure our installations meet both NYC Landmarks Preservation Commission rules and current energy codes.

On the White Street lot-line project in TriBeCa, we installed 350 lb., 10 ft. tall Optimum fire-rated steel lot-line windows. Along with fire safety, these units were built with thermally broken frames and high-performance glazing that meet today’s code and are equipped to satisfy future standards.

Are Landmark Windows Worth It Compared to Newer Competitors?

From our perspective, absolutely. Many off-the-shelf windows may seem like a bargain, but they often won’t pass Landmarks review, which can cost you time and money. Landmark Windows give you the best of both worlds: code compliance, long-term energy savings, and historic accuracy. That combination is what makes them a smart investment in the long run.

At 17 St. Luke’s Place, we installed Parrett double-hung and French casement windows with custom brick moulds and interior casing. Parrett’s test data shows their windows achieving STC ratings into the high 30s and OITC ratings in the 30s, depending on glazing. That means you’re not only getting historically accurate units but also proven acoustic and energy performance.

What’s the Current Warranty and Performance Rating of Landmark Windows?

Manufacturers we work with provide strong warranties that cover frames, glazing, and finishes. Performance ratings meet or exceed industry standards, offering peace of mind that your investment delivers both beauty and efficiency for decades.

17 St. Luke’s Place | Parrett Windows Custom Double Hung & French Casement Windows (Landmark Approved)

White Street, TriBeCa | Optimum Window Single Hung Steel Fire-Rated Lot Line Windows (DB/OITC Rated, Landmark + Code Compliant)

NYC | Double Pane Weight & Chain Windows (Landmark Approved, Energy Efficient, Code Compliant)

East Village | Parrett Windows Triple Hung Weight & Chain Windows (Landmark Reproduction)

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Door Anatomy | Guide to Parts, Terms and Functions

The anatomy of a door, exterior.

When it comes to historic preservation, the elegance of a door lies not only in its design but also in its anatomy. From grand entryways in landmark buildings to charming brownstone doors in New York City, understanding the parts of a door can help you make more informed decisions. Here’s a breakdown of the essential components that make up a traditional door system.

The Basics

Doorway
The doorway is the opening itself, the passage you walk through to enter a home or room.

Door Frame
Supporting the door panel, the frame includes three key parts: the head (top), jambs (sides), and sill (bottom). Frames are typically constructed from wood, steel, or aluminum, depending on the style and era of the building.

Door Panel
This is the main part of the door that swings open and shut. It can feature solid wood, glass panes, or decorative detailing, depending on the architectural style.

Structural & Functional Elements

Head (or Door Head)
The horizontal top part of the frame.

Jamb
The vertical sides of the frame where the hinges, latch, and strike plate are mounted.

Sill
Located at the bottom of the frame, it sits flush with the floor.

Threshold
Often a sloped piece installed over the sill, the threshold helps keep water and drafts from entering the home.

Weatherstripping & Door Sweep
These components are critical for sealing gaps and improving energy efficiency. Weatherstripping lines the perimeter of the door panel, while the door sweep covers the gap at the bottom.

In-Swing vs. Out-Swing
Depending on your building’s layout or historical context, doors may swing inward or outward. This is typically determined by the positioning of hinges and how the space is used.

Design & Decorative Components

Rails & Stiles
Rails are horizontal segments on the door panel, while stiles run vertically. These structural elements often define the style of the door and house the hardware.

Mullions
A mullion (or “mull”) is the vertical or horizontal element that separates and joins multiple door panels or connects sidelights or transoms to the main door.

Casing & Brickmould
These trim elements add architectural interest and help hide the transition between the door frame and wall—casing on the interior and brickmould on the exterior.

Grilles
Grilles are decorative dividers that mimic the appearance of individual glass panes. They can be surface-applied or installed between panes of insulated glass.

Dentil Shelf
A signature feature of craftsman-style doors, this is a small ledge typically placed below a window pane for decorative effect.

Glazing (Glass)
Historic doors often feature beautiful glasswork. Today, glazing is usually insulated and may include decorative patterns, beveled edges, or leaded details.

Sidelights & Transoms
Sidelights are narrow, vertical windows flanking the door, while transoms sit above it. Both let in natural light and add visual grandeur to an entryway.

Hardware & Security Features

Hinges
These allow the door panel to pivot open and closed. Styles range from exposed barrel hinges to concealed or pivot hinges in modern or minimalist applications.

Knob or Handle
The main mechanism for opening a door. Knobs are round, while handles can vary in design—lever or pull-style depending on preference and accessibility.

Lockset
This includes all elements related to door locking: the handle, latch, strike plate, and interior locking mechanisms.

Deadbolt
An added layer of security, the deadbolt slides a solid metal bolt into the frame and is usually operated by a key or thumb turn.

Latch
The latch retracts when the handle is turned, allowing the door to open. It extends automatically when the door is closed.

Mortise Plate & Strike Plate
These metal reinforcements are located in the jamb and receive the latch or deadbolt. They enhance security and durability by preventing forced entry.

Astragal
If you have double doors, the astragal is the vertical strip that seals the gap between both panels and helps keep the doors secure and aligned.

Planning a full exterior restoration? Don’t miss these window guides.

Understanding window parts is key to choosing, restoring, and preserving historic windows. Learn more in our Window Anatomy Guide, and explore glass types and glazing details in Glass: What a Pane.

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A Lot on the Line | Installing Fire-Rated Lot Line Windows in TriBeCa

Installing 350-pound, 10-foot-tall steel fire-rated ceramic glazed lot line windows is no easy feat—especially in a historic TriBeCa building with just five feet of clearance between neighboring structures. When working several stories up, over skylights and alleyways, precision is key. These projects demand careful planning, expertise, and patience to ensure both compliance and craftsmanship.

We recently undertook the replacement of 130-year-old double-hung wood weight and chain windows on White Street—one of our favorite streets in Lower Manhattan, where we’ve worked on numerous projects over the years. Given the building’s age and NYC’s strict building codes, these new single-hung steel windows from Optimum Window were essential. The upgrade ensures compliance with both fire safety regulations and NYC Landmarks Preservation Commission requirements while preserving the historic character of the building.

Why Lot Line Windows Matter

Lot line windows are installed on walls that sit directly along a property line, meaning they must meet fire-rated standards to protect against potential fire spread between closely spaced buildings. These new steel-framed windows provide:

• Improved Fire Safety: The ceramic glazing and thermally broken steel frames enhance the fire resistance required for lot line windows.

• Sound Attenuation: The DB/OITC-rated glazing significantly reduces noise pollution—a major benefit in New York City.

• Energy Efficiency: The insulated steel frames and thick glazing offer better thermal performance, keeping interiors more comfortable year-round.

Preserving History While Enhancing Performance

One of the most rewarding aspects of this project was the careful attention to historical detailing. Custom interior casings were fabricated to match the original woodwork, ensuring that the new windows blend seamlessly into the building’s architectural style.

As this transformation nears completion, it’s clear that upgrading historic windows is more than just an aesthetic choice—it’s a structural and safety necessity. With proper planning, expert craftsmanship, and respect for historical integrity, even the most challenging projects can be executed flawlessly.

Top 5 Architectural Window Styles in Historic New York Homes

New York City is known for its rich architectural history, with buildings that showcase a variety of window styles from different eras. These windows not only contribute to the aesthetic beauty of the buildings but also reflect the cultural and historical significance of the time in which they were built. Understanding the different window styles can help you preserve your building’s original charm while ensuring compliance with preservation laws.

As a leading window company in New York City, we specialize in restoring and replacing landmarked windows and custom historic windows. Below, we explore the top five architectural window styles found in historic New York homes and buildings, offering insights into how they can be restored or replicated.

Double-Hung Windows

Double-Hung Windows

One of the most common window styles found in historic New York homes is the double-hung window. These windows feature two vertically sliding sashes, allowing both the top and bottom panes to be opened. Double-hung windows were popular in many architectural periods, from Colonial and Federal styles to Victorian townhouses and brownstones.

If your building has original double-hung windows, preserving their function and appearance is essential. Our window company near you can restore or create custom historic windows that maintain the traditional look while improving energy efficiency with modern materials.

Casement Windows

Casement Windows

Casement windows, which open outward like a door, are another common feature of historic homes, especially in early 20th-century buildings. These windows offer excellent ventilation and were often used in high-end townhouses and early apartment buildings.

Restoring historical windows like casement windows requires precision and expertise to retain their original design. Our window replacement services in New York City ensure that any casement window replacements match the building's architectural period.

Palladian Windows

Palladian windows, known for their grandeur, feature a large central window flanked by two smaller, arched windows. This design originated in classical European architecture and became popular in New York during the 19th century, especially in grand estates and public buildings.

Bay Windows

These elegant windows are often focal points of historic buildings, making restoration critical. Our window company in NYC specializes in landmarked window restoration, ensuring that your Palladian windows retain their beauty and compliance with NYC preservation laws.

Arched Windows

Arched windows are a hallmark of Beaux-Arts and Romanesque Revival architecture, two styles that heavily influenced New York's historic buildings. These windows feature rounded tops and intricate detailing, often found in churches, libraries, and ornate residential buildings.

Restoring arched custom historic windows requires careful attention to detail to preserve their intricate design. Our team is skilled in restoring these complex windows, maintaining their structural integrity while upgrading them to meet modern energy standards.

Bay Windows

Bay windows, often found in late 19th and early 20th-century townhouses, extend outward from the building’s façade, creating more interior space and allowing for additional light. These windows are commonly seen in Victorian and Queen Anne-style homes throughout New York City.

Replacing or restoring bay windows can be tricky due to their unique shape and size, but our window company near you specializes in creating custom historic windows that perfectly replicate the original style. We also offer solutions for improving insulation and weatherproofing, keeping the look authentic while enhancing performance.

Why Custom Historic Windows Matter for Landmark Preservation

Preserving the original architectural window styles in landmarked and historic properties is crucial for maintaining the building’s authenticity and complying with New York City’s preservation laws. The Landmarks Preservation Commission (LPC) requires that any restoration or replacement of landmarked windows matches the original design and materials, ensuring the building retains its historical significance.

At our window company in NYC, we have extensive experience working with historical homes and buildings, offering custom solutions for window restoration and replacement. Whether you're dealing with aging double-hung windows or intricate Palladian windows, we ensure that every project meets the LPC’s guidelines and enhances the overall value of your property.

Contact Us for Historic Window Restoration in New York City

If you’re looking to restore or replace the windows in your historic New York home, our team is here to help. As a trusted window company near you, we specialize in landmarked window restoration and custom historic windows that retain the beauty and integrity of your building’s original design.

Contact us today to schedule a consultation and learn more about our window replacement services in New York City. Let us help preserve your property’s unique architectural style while improving its functionality and energy efficiency.

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A Window to the Past | Reviving 214 West 16th Street

Nestled in the heart of New York City, 214 West 16th Street stands as a captivating example of architectural evolution. Built in 1898, this brick building seamlessly blends the Federal Style with touches of Neoclassical, Beaux-Arts, and Baroque elements. The intricate design of its facade, shared with its sister buildings next door, reflects the pride and craftsmanship of a bygone era. From Limestone and Terracotta arches to detailed coursing and carvings, every aspect of this building tells a story of meticulous attention to detail.

In our latest project, we were honored to restore a piece of this history by installing period-perfect, 2 over 2 NorClad Double-Hung windows from Norwood Windows And Doors. These windows, approved by the New York City Landmarks Preservation Commission, were carefully chosen to match the original aesthetic while offering modern performance. The rear of the building now features these historically accurate windows, complete with custom exterior metal brick mould capping and interior casing.

This transformation was not just about replacing windows; it was about reclaiming the building's original charm. We said goodbye to the black aluminum inserts and single-pane windows that had previously marred the structure's beauty, embracing a solution that honors the past while enhancing the building's functionality.

We invite you to explore the before-and-after journey of this restoration, where history and modernity meet in perfect harmony.

Before

After

Restoring History | Window Replacement at Mercer Street

In the heart of Manhattan's vibrant SoHo neighborhood, Mercer Street stands as a testament to the city's rich architectural heritage. Built in 1920, this five-story, five-unit building boasts a classic SoHo loft style with a historic cast-iron, brick, and limestone facade that epitomizes the neighborhood's charm.

However, maintaining such historic beauty comes with its challenges, particularly when it comes to preserving the building's original windows. These windows not only contribute to the building's aesthetic appeal but also serve as a vital link to its past.

Recently, in an effort to uphold the building's authenticity while enhancing its functionality, a comprehensive window replacement project was undertaken. The task at hand? Replacing all the historic oversized Double-Hung Mahogany Weight and Chain windows, each boasting dimensions of over 5 feet wide by 8 feet tall. These windows, approved by the New York City Landmarks Preservation Commission, are an integral part of the building's identity.

It's worth noting the sheer magnitude of the undertaking – the counterweights for each sash weighed a staggering 160 pounds! Such intricate details highlight the craftsmanship and attention to detail that went into the original construction of 153 Mercer Street.

Beyond its architectural significance, Mercer Street holds a special place in New York City's history. Originally known as Clermont Street and laid out prior to 1797, the street was renamed in 1799 in honor of General Hugh Mercer, an American soldier who made the ultimate sacrifice during the Battle of Princeton in 1777.

Moreover, SoHo, short for "South of Houston," is renowned for its elegant cast-iron facades, cobblestone streets, and a vibrant mix of boutiques and restaurants. It serves as an atmospheric backdrop for fashion, movies, and bustling tourist crowds. Often, it's mistakenly identified with TriBeCa, which stands for "The Triangle Below Canal Street," another historic neighborhood in Lower Manhattan.

For companies like ours, specializing in historical window restoration, neighborhoods like SoHo and TriBeCa are more than just locations – they're playgrounds of preservation. With a portfolio boasting hundreds of restored buildings, we at Historical Windows of New York take pride in our role in safeguarding the character and charm of the city we call home.

From meticulously crafted window replacements to immersive walking tours showcasing our restoration projects, we are committed to honoring the legacy of New York City's architectural treasures. 153 Mercer Street serves as a shining example of our dedication to preserving the past while embracing the future.