Restoring Old Windows: A Step-by-Step Guide

Heat gain and loss through windows can account for up to 30% of a home’s heating and cooling use, according to the Department of Energy. So, when you notice drafts, cracks, or spot a defect in your frame, it’s in your best interest to consider restoring or replacing your old windows.

Upgrading to today’s energy-efficient windows can help reduce utility bills, but in some instances, restoration may be the better option. “Restoring old windows can make sense if you’re dealing with historic homes where maintaining architectural integrity is a priority,” said Jake Zahnow, owner of Window Pro in Wixom, Michigan. “If the window frames are made from quality wood and just need some reglazing or weatherproofing, restoration can preserve charm and function.”

Restoration also makes sense when the damage is minor and the restoration cost is lower than the replacement cost. However, in many cases, especially with aging or inefficient windows, replacement is often the best option.

Below, we’ll explore when it’s best to replace versus restore your windows, how to restore your windows, and which projects necessitate calling a window professional.

When Restoring Old Windows Is Worth It

Restoring windows makes sense in a few circumstances: if the windows are part of a historical home, if the frames are constructed from high-quality materials like old-growth wood, or if the damage is minimal and it would be less costly to repair the windows than to replace them.

There’s also the environmental impact — restoring windows keeps them out of the landfill.

Here are some signs that your windows are good candidates for restoration:

• There’s limited water damage or wood rot on the window.
• You have single-pane windows and can add storm window inserts for increased efficiency.
• The sash and frame are in good working order.

When It’s Better To Replace

When you have safety concerns or see extensive damage, your windows may be beyond repair. “Rotting or warped wood, cracked or foggy glass, and nonfunctioning hardware are all red flags,” Zahnow said. “If you’ve got drafts, leaks, or visible mold, those are usually signs the window system has failed beyond what restoration can reasonably fix.”

Other signs that replacement is the better option include sagging frames, termite damage, or windows that no longer open. If your energy bills remain high even after adding storm window inserts, it may also be time for new windows.

How To Restore Old Windows

In cases of minor damage, restoring old windows can be a suitable project for capable DIYers. The best candidates for restoration are wooden windows with single-pane glass (common in older or historic homes). Here’s how to restore minor damage.

Step 1: Inspect and Evaluate the Window

Evaluate your windows to determine whether they’re good candidates for restoration. Look for signs of damage on and around the frames and inspect the glass for any cracks. Often, drafty windows result from worn weather stripping, a material that’s placed around the perimeter of the window to block drafts and seal gaps. This material is often foam or felt strips. If the weather stripping is torn, sagging, or has gaps, it will need to be replaced.

Also, open and close the windows to make sure they’re fully operable. Windows that stick, jam, or won’t stay open may require mechanical repairs or more extensive restoration.

Step 2: Remove Old Paint, Glazing, and Hardware

Before removing old paint, make sure it’s lead-free. Use a DIY lead test kit or have the paint professionally tested for lead. If you’re in the clear, proceed to make repairs.

Remove only the components necessary for repairs. This may include old paint, hardware, or glazing. If you need to replace a piece of broken glass, it’s best to remove the window sash first.

Step 3: Repair or Replace Window Components

For minor cracks or divots in your wood window frames, repair with wood epoxy. Allow the epoxy to fully cure before sanding or painting.

If a new pane of glass (in the case of single-pane windows) is needed, consult with a local window shop or home improvement store. These businesses can cut glass to size, just make sure it’s the appropriate thickness for your window.

To install a new window pane, follow these steps:

• Apply a window glazing putty around the window sash’s perimeter.
• Press the glass into the glazing compound.
• Install glazing points (small metal fasteners) evenly around the edge of the glass, about every 10 inches.
• Apply a bead of glazing compound around the perimeter of the glass to seal it, and smooth it out with a putty knife or your wet finger.

Replace any sash cords, sash weights, or pulleys as needed.

Step 4: Sand, Paint, and Seal

Once repairs are complete and the sash is reassembled, sand the wood frames. Then, paint the frames with a weather-resistant exterior paint. Finally, seal any gaps around the window with caulk to prevent drafts from entering.

How Much Does Window Restoration Cost?

The price of window restoration depends on the type of repairs and the number of windows. The national average window repair cost ranges from $100 to $800, according to Gal Cohen, the field area manager at JDM Sliding Doors in Fort Lauderdale, Florida. The cost to replace window glass is about $300–$700 per window.

According to Zahnow, if you have historic windows, restoration prices might be even higher. “Basic repairs like new weather stripping or fresh glazing might be inexpensive, but true restorations, especially on older or historically significant windows, often require custom millwork and skilled labor,” he said. “At times, full restoration can actually cost more than high-quality replacements.”

DIY Vs. Hiring a Pro

Restoring windows is possible for DIY enthusiasts with prior experience and the appropriate set of tools. However, DIY restoration jobs are best when windows are easily accessible (on the first floor) and have minimal damage.

When multiple windows require restoration, repairs are complex, or the job spans several stories, it’s time to call in a pro. True window restoration, especially for historic windows, is a craft and may require a contractor who specializes in this area.

“It often involves specialized tools and techniques, not to mention safety risks with old glass and lead paint,” advised Zahnow.

Improving Energy Efficiency in Restored Windows

Sometimes, small upgrades make a big difference in your windows’ energy efficiency. If you’re trying to delay the cost of new windows, try these tactics to make your restored windows more efficient.

• Install storm window inserts. Storm window inserts can reduce heating and cooling loss. Exterior inserts protect against harsh weather, while interior inserts can preserve your home’s curb appeal.
• Replace missing or worn weather stripping and caulk. Sealing small gaps with weather stripping or caulk prevents drafts and heat loss.
• Apply insulating window film in the winter. To help keep warm air inside during frigid winter months, grab an inexpensive insulation window film and apply it to your windows.
• Layer up shades and thermal curtains. Thick curtains and shades also act as insulators, helping combat heat gain in summer and heat loss in winter.

Next Steps

Restoring old windows can preserve your home’s character and keep materials out of the landfill. And, in some cases, especially when damage is minor, it can also be more cost-effective than complete window replacement.

To determine whether restoration is an option, start by evaluating your windows for damage. If the issues are minimal, consider repairing one window as a test restoration project or hiring a professional to handle the job. “In most cases, I’d recommend homeowners consult with a professional, especially if the windows are historic or if performance is a top priority,” Zahnow said.

Once windows are restored, enhance their energy efficiency by using storm windows or window films.

FAQs About Restoring Old Windows