Restoring old windows adds charm and character to a home, but cracked, crumbling putty can turn that charm into a drafty nightmare. If you want to preserve the architectural value of your home without spending a fortune, window glazing is your best solution.
Reglazing a window is a manageable DIY project that doesn’t require professional skills. With a little patience and the right tools, you can seal out the elements and achieve a high-end finish. Here is how you can do it yourself.
Key Takeaways
- Window glazing refers to the putty (compound) that secures the glass to the frame and seals out weather.
- The restoration process involves removing old putty, priming bare wood, inserting glazier’s points, and applying new compound.
- Reglazing is significantly cheaper than replacement, often costing less than $50 for a DIY project compared to hundreds for new units.
- You should choose reglazing over replacement if you want to maintain historical accuracy or if the wood frames are still solid.
What Is Window Glazing?
The term “glazing” can get confusing because it refers to three different things. Technically, glazing is the glass pane itself. However, in the DIY world, it usually refers to the “glazing compound” or putty used to seal the glass to the wood frame.
Finally, glazing also describes the actual act of applying that putty.
For this guide, we are focusing on the process: how to remove the rock-hard, cracked putty from your old single-pane windows and replace it with fresh compound.
How to Reglaze a Window Step-by-Step
The glass on older windows sits in a bed of putty that hardens over time. After decades of exposure to sunlight and rain, this compound cracks and falls out. This lets water rot the wood and allows heat to escape.
You can fix this in an afternoon. Before you start scraping, you need to gather the right supplies.
Tools and Materials
- Razor knife.
- Stiff putty scraper.
- Heat gun (or infrared stripper).
- Glazier’s points (crucial for holding the glass).
- Sandpaper (100 to 120 grit).
- Glazing compound (oil-based or latex).
- Oil-based primer.
- Sash brush.
- Lead paint test kit (for older homes).
1. Remove the Sash
While it is possible to glaze a window vertically, gravity makes it difficult. It is much easier to work on a flat surface. Remove the stops (the wood strips holding the window in) and carefully take the sash out of the frame.
Place the sash on a workbench or sawhorses. If there is paint sealing the stops, score the paint line with a razor knife first to prevent chipping.
2. Remove the Old Glazing
You need to remove 100% of the old, cracked putty. Use a stiff scraper or a specialized glazing knife to chip it away.
If the putty is rock-hard, use a heat gun to soften it. Move the heat gun constantly to avoid cracking the glass or scorching the wood.
Safety Warning
Old windows often contain lead paint. Always test for lead before sanding or scraping, and wear a respirator if lead is present.
3. Prep and Prime the Frame
Once the wood is bare, inspect it for rot. If you find soft spots, dig them out and fill them with a two-part wood epoxy. Sand the frame lightly to ensure a smooth surface.
This next step is critical: Prime the bare wood with an oil-based primer.
Many people skip this, but dry wood will suck the oils out of your new glazing compound, causing it to dry out and fail prematurely. Let the primer dry completely before moving on.
4. Secure the Glass
If you removed the glass to clean it or repair the bed, place it back into the frame. Push “glazier’s points” (small metal triangles) into the wood frame every 6 to 8 inches.
These points are what actually hold the glass in place; the putty is just a weather seal. Ensure the points are pressed flat against the glass.
5. Apply the Glazing Compound
Knead a handful of glazing compound in your hand to warm it up. It should feel like soft dough. Roll it into a “snake” or rope about the thickness of a pencil.
Press this rope firmly into the corner where the glass meets the wood. You want to overfill it slightly to ensure there are no air gaps.
6. Smooth the Joint
Hold your putty knife at a 45-degree angle. Drag it firmly along the line of putty in a single, smooth motion to create a clean, angled bevel.
This angle helps water run off the glass rather than pooling. If the putty pulls away or looks rough, just scrape it out and try again. Clean up the excess from the glass and corners.
7. Paint the Glazing
You cannot paint immediately. Oil-based glazing putty takes a long time to “skin over” (form a firm surface). This can take anywhere from a few days to a few weeks depending on humidity.
Once a skin forms, paint the putty with a high-quality exterior paint. Crucial tip: Lap the paint onto the glass by about 1/16th of an inch. This paint seal prevents water from getting behind the putty.
Cost to Reglaze Windows
Reglazing is incredibly cost-effective compared to replacement. If you hire a professional, expect to pay between $250 and $500 per window sash. This price accounts for the labor-intensive process of scraping and curing.
If you go the DIY route, your costs drop drastically. A tub of glazing compound, a few tools, and primer will cost you less than $50 total. Since one tub covers multiple windows, the cost per window is negligible.
How to Reglaze a Window Without Removing It
Sometimes, you cannot remove the sash because it is painted shut or stuck. In this case, you can reglaze it in place (in situ).
The process is the same, but you will have to fight gravity. Use stiffer putty and smaller sections to prevent the compound from sagging before you smooth it. This method is faster but can be harder on your back and arms.
Reglazing vs. Replacing Windows
Should you spend the weekend scraping putty, or should you just buy a new vinyl window? It depends on your goals and the condition of the home.
Here is when you should consider a full replacement:
- Severe Rot: If the frame crumbles when you touch it, putty won’t save it.
- Efficiency Needs: Single-pane windows will never be as efficient as double-pane gas-filled windows.
- Functionality: If the sash weights are broken and the window won’t stay open, replacement might be easier than a full mechanical restoration.
When to Choose Reglazing
I usually vote for restoration. Here is why you might want to stick with the original windows.
Historical Integrity
Original wood windows are made from “old-growth” timber, which is denser and more rot-resistant than modern wood. Vinyl replacement windows often look out of place on a historic home and can actually lower the property value of period houses.
Cost Savings
Replacing a whole house of windows can cost $10,000 to $30,000. Restoring them yourself costs a few hundred dollars in supplies. If the wood is solid, reglazing offers the best ROI.
Sustainability
Repairing what you already have is always greener than manufacturing new plastic windows. By reglazing, you keep old materials out of the landfill and reduce your carbon footprint.
FAQs
Here are the most common questions homeowners ask about the reglazing process.
How Often Do Windows Need to Be Reglazed?
Properly applied and painted glazing can last 20 to 30 years. You should inspect your windows annually for cracks or loose putty to catch problems early.
Is It Hard to Reglaze Windows?
The technique is easy to learn, but the work is tedious. The hardest part is removing the old, hardened putty without breaking the glass.
How Long Does Glazing Putty Take to Dry?
Oil-based compounds remain soft for a long time to allow for expansion. They typically need 7 to 14 days to form a skin before painting. Latex or water-based compounds can be painted in as little as 2 hours.
Can I Use Silicone Caulk Instead of Putty?
Technically yes, but it is not recommended for traditional wood sashes. Silicone is incredibly difficult to remove later if repairs are needed, and it often looks messy compared to the clean lines of traditional glazing compound.
Can You Glaze Over Old Glazing?
No. You must remove the old, loose putty. Putting new compound over failing putty traps moisture and ensures the new layer will fall off quickly.
What If I Break the Glass?
It happens to the best of us. If the glass breaks, wear heavy gloves to remove the shards, measure the opening, and have a local hardware store cut a new single-strength pane for a few dollars.
What Are Glazier’s Points?
Glazier’s points are small metal triangles or diamond-shaped clips that are driven into the wood frame. They serve as the primary structural support that holds the glass pane in the sash; the putty merely acts as a sealant.
Final Words
Now that you know how to reglaze a window, you can tackle those drafty sashes one by one. It is a project that rewards patience over speed. Take your time cleaning the frame and smoothing the compound, and your windows will look beautiful for decades to come.
