How to replace a broken window pane and reglaze the sash
Replacing a broken window pane and reglazing the sash is a manageable weekend project that saves money and restores weatherproofing. With basic tools, a bit of time, and attention to detail, you can remove the broken glass, prepare the sash, install new glass, and apply fresh glazing for a durable seal.
Step 1: Measure and order glass
Measure the inside dimensions of the rabbet (the recess that holds the glass) in three places: top, middle, and bottom. Subtract 1/16 to 1/8 inch from the smallest measurement for clearance, then order annealed or tempered glass of the correct thickness (usually 1/8", 3/16", or 1/4") from a local glass shop; expect turnaround of 1–3 days.
[Illustration: person measuring window sash interior with tape measure and notebook]
Step 2: Remove remaining broken glass
Wear heavy gloves and eye protection and remove loose shards by hand, then use pliers to pull out stubborn pieces. Dispose of glass in a sturdy container, sweep the sash and surrounding area with a brush and vacuum to remove tiny slivers; this prevents cuts and ensures a clean seat for the new pane.
[Illustration: gloved hands removing shards from wooden sash with pliers and vacuum nearby]
Step 3: Take out old glazing compound
Use a utility knife and a stiff putty knife or paint scraper to cut through and pry out the old glazing compound and glazing points; for painted-over putty, score both sides and gently heat with a heat gun at 200–300°F (93–149°C) to soften the compound. Remove all residue to a clean, slightly rough wood surface so the new compound bonds well.
[Illustration: close-up of putty knife scraping hardened glazing from sash corner with heat gun in background]
Step 4: Prepare and prime the rabbet
Sand the rabbet smooth with 80–120 grit sandpaper and remove dust with a damp cloth. If the wood is bare or the old paint is failing, apply a coat of exterior-grade oil or latex primer and let dry 2–4 hours to prevent moisture absorption and improve adhesion of glazing compound.
[Illustration: sanded wooden sash rabbet being wiped clean with cloth, primer can and brush nearby]
Step 5: Set the glass and secure
Put a thin bed of linseed oil or a dab of glazing putty on the rabbet bottom, then carefully set the new glass into the frame. Insert bronze or stainless-steel glazing points every 6–8 inches, pressing them flush with a putty knife to hold the pane squarely without stressing the glass.
[Illustration: new glass placed in sash with gloved hands inserting glazing points using putty knife]
Step 6: Apply glazing compound smoothly
Knead exterior-grade glazing compound until soft, then roll into a rope and press a 3/8" to 1/2" fillet against the edge of the glass with a putty knife, forming a smooth 45-degree bevel. Work in sections and tool the putty neatly; glazing seals the glass and sheds water, so smooth, continuous beads improve durability and appearance.
[Illustration: hand tooling fresh glazing compound into smooth beveled bead around glass edge with putty knife]
Step 7: Paint and cure the putty
Allow the glazing compound to skin for 3–7 days (depending on temperature and product) before priming; then apply one coat of primer and two coats of exterior paint, waiting recommended dry times (usually 2–4 hours) between coats. Full cure may take 2–4 weeks—painting sooner protects the putty and prevents shrinkage cracks.
[Illustration: brushed paint on glazed sash with paintbrush and small paint can nearby]
- Work on a dry day above 50°F (10°C) so glazing compound cures properly.
- Buy 10–15% more glazing points and putty than you think you need to account for mistakes.
- Label measurements and photograph the old glazing layout before removal to replicate bead thickness and point placement.
- Use a single-edged razor scraper for final clean-up of glass edges; replace blades often for a clean cut.
- If the sash is rotted, repair or splice wood before glazing to ensure a firm seating surface.
- Consider using blocks of wood and shims to square and level the glass while the putty skins.
- Always wear cut-resistant gloves and safety goggles when handling broken glass to avoid serious injury.
- Do not use silicone or construction caulk in place of glazing compound; these do not bond properly and can trap moisture, causing rot.
- Avoid applying glazing compound in temperatures below 40°F (4°C) or above 90°F (32°C) as it will not cure correctly and may crack.
- If the window is insulated glass (double pane) or part of a structural unit, replacing individual panes may not be appropriate—consult a professional.
Was this guide helpful?
More Home & Garden guides
How to solder copper water pipes and replace a leaking compression joint
This guide walks you through soldering copper water pipes and replacing a leaking compression joint in a clear, step-by-step way. You’ll learn how to cut, clean, flux, solder, and reassemble a compression fitting so the joint becomes watertight. Follow safety tips and take your time—most DIYers finish a simple repair in 60–90 minutes.
How to install a ceiling fan with remote control and balance the blades
Installing a ceiling fan with a remote adds comfort and convenience to a room. This guide walks you through the main steps—from power off to balancing blades—so you can complete the job in about 2–4 hours with basic tools and a helper.
How to build and install a sturdy floating bookshelf on drywall
Building a sturdy floating bookshelf on drywall is an achievable weekend project that adds clean storage without visible brackets. With proper anchors, a solid cleat, and attention to level and load, you can support 50–100 pounds safely depending on materials. Follow these steps carefully and measure twice before cutting once.