A Homeowner’s Guide to Heritage Window Replacement

Restoration vs. Replacement

Before you call a contractor, you need to determine if your windows are truly "dead" or just sleeping.

The Case for Restoration:

Many heritage windows are made from old-growth timber. This wood is incredibly dense and rot-resistant—far superior to the quick-growth pine used in many modern off-the-shelf windows. If the frames are solid, restoration (stripping paint, re-roping pulleys, and weatherstripping) is often more sustainable and keeps the home’s appraisal value high.

The Case for Replacement:

Sometimes, history has been unkind, especially when considering Ottawa weather. If you see "soft" wood (structural rot), significant frame warping, or if a previous owner replaced the originals with cheap, ugly inserts, it’s time for a full replacement.

Navigating Regulations

If your home is in a conservation district or is a designated landmark, you can’t simply pop over to a big-box store and buy a vinyl window.

Most heritage committees require a Heritage Permit. They look for "like-for-like" replacements. This means the new window must match the original in:

• Profile: The thickness and shape of the wood frames.
• Muntins: The "bars" that divide the glass panes (these should be structural, not snap-on plastic).
• Operation: Replacing a sliding sash with a crank-operated casement is usually a big "no."

The Art of the "Fake": Why Simulation Wins

For years, homeowners were forced to choose between the astronomical costs of custom millwork or the architectural "sin" of installing flat, plastic-looking modern windows.

Today, a new category of Simulated Heritage Solutions has emerged. This approach leverages high-precision technology to mimic the soul of 19th-century craftsmanship while delivering the thermal performance of a 21st-century laboratory.

The primary objection to non-wood windows has always been their "flatness." Historic windows have depth; they have shadows. Modern technology now bridges this gap through three specific engineering feats:

Putty-Line Detailing:

Modern CNC machining can now replicate the distinct 45-degree "putty" bevel where the glass meets the frame. This creates the sharp shadow lines essential to a historic facade.

Mechanical Joinery:

Traditional PVC or aluminium windows use diagonal welds. New "Timber-Alternative" systems use mechanical butt joints that mimic the vertical-to-horizontal joinery of a master carpenter.

Variable Sightlines:

Instead of one-size-fits-all frames, modern systems use "dummy sashes" and staggered frame depths to ensure that every pane of glass—whether it opens or not—looks perfectly symmetrical.

Other Alternatives:

Bridging the Craftsmanship Gap

While a professional millwork might cost $3,000 to $5,000 for a single mahogany sash, simulated solutions offer a 30% to 50% cost reduction without the "cheap" aesthetic.

High-Tech Performance, Low-Profile Look

The greatest "magic trick" of modern window technology is hiding the bulkiness. Historic homes look elegant because their window frames are slim.

Vacuum Insulated Glass (VIG):

This is the game-changer. VIG units are only 6mm to 10mm thick (the same as a single historic pane) but offer the insulation of a 1-inch thick triple-glazed unit. This allows for deep, historic millwork profiles without the "bug-eye" look of thick glass.

Argon & Low-E Coatings:

Modern glass incorporates microscopic metallic layers that reflect heat back into the room. When combined with simulated divided lites (SDLs), you get the look of individual panes with the airtight seal of a single continuous sheet. Note: some Low-E coatings have a slight tint.

How to Choose

If you are balancing a budget against a love for history, follow the "10-Foot Rule": If a window is indistinguishable from original millwork from 10 feet away, it is a successful heritage solution.

Match external Grids

Look for Simulated Divided Lites (SDL) with an internal spacer bar for a "see-through" authentic effect.

Match the Hardware

Don't use plastic latches. Invest in authentic forged brass or iron hardware if available. The hand-touch is where the "feeling" of quality lives.

Specify Deep Rails

Historic windows almost always have a taller bottom rail than the top. Ensure the manufacturer can vary these dimensions.

Window Frames

Look for sloped, bevelled "putty-line" profiles

Glass

You'll want to use clear, Low-E glass with neutral coatings

Welded Corners

Try to find Vertical/Horizontal "butt" joints, you may have to settle for diagonal "welded" corners, which are not period characteristic.

Find the Right Service

Most window replacement companies are looking for a fast return. Search for a professional who is willing to listen to your requests, one who will not push you towards a compromised alternative.

Things to Avoid

Avoid The InsertTrap

Be wary of "Pocket" or "Insert" windows. This is where a new window is slid into the existing frame. Because you are putting a frame inside a frame, you lose significant glass area. Your windows will look smaller, and your rooms will feel darker. For heritage homes, a Full-Frame Replacement is almost always the better aesthetic choice.

Avoid Internal Grids

Never put the decorative bars between the glass. It kills the reflection and looks fake.

Avoid Tints and Non-clear Coatings

Tinted or highly reflective glass is an instant heritage fail giveaway

Bayview's Brands: Canadian Weapons Against the Cold

At Bayview Windows, we’ve spent 30 years helping Ottawa homeowners find the middle ground for Simulated Heritage Solutions. Our approach uses modern, Canadian-made technology to mimic the deep profiles and "shadow lines" of historic windows at a fraction of the cost of artisanal millwork.

Martin Windows & Doors

The "Ancestral" line is the gold standard for heritage. They offer genuine wood interiors but use modern weatherstripping and triple-pane options that the original builders couldn't have imagined.

Del (The "Weather Fighter")

Their Bayview line is engineered specifically for our climate, featuring architecturally bevelled frames that mimic the look of traditional wood putty but in a maintenance-free PVC.

North Star

Ideal for "character homes" that aren't under strict heritage designation. They provide the thin sightlines and high-efficiency Zone 3 ratings needed to keep the furnace from running 24/7.

The Tech: Glass Performance with Modern R-Values

How do you mimic a 100-year-old window without the 100-year-old drafts?

Simulated Divided Lites (SDL)

Forget those "grids-between-the-glass" that look like plastic stickers. We use SDLs that are mounted on top of the glass, creating a real shadow line. From the sidewalk in Rockcliffe, they are indistinguishable from individual panes.

The Triple-Pane Secret

In Ottawa, double-glazing is often not enough. Many of our Martin and Del options allow for triple-pane glass that fits within a heritage-profile frame. You get the look of a thin Victorian sash with the insulation value of a modern wall.

Battling the Climate Zone

As of the current Energy Star Version 5.0 guidelines, Canada has eliminated climate zones in favour of a single, nationwide performance floor. To be certified today, any window installed in your Ottawa home must meet these rigorous metrics

For those looking for the "best of the best," the Energy Star Most Efficient category pushes those bars even higher (U-factor of 1.05 or an ER of 40), which is often the sweet spot for Ottawa’s deep freezes.

Conclusion: Investing in Legacy

Heritage window replacement isn't just a maintenance task; it’s a restoration of your home’s soul. By matching the original proportions and choosing high-quality materials, you ensure that your home remains a neighbourhood treasure for another hundred years, while finally being able to sit by the window without wearing a parka.