How to Replace a Cracked Windowpane (5 Steps That Save $200)

TL;DR: Replacing a single-pane window costs $150–$350 if you hire a glazier, but you can do it yourself for around $30 in materials and two hours of time. You'll need the correct glass size (measure the rabbet, not the old pane), glazing compound, glazier's points, safety gear, and a steady hand. The process: remove the old pane and putty, prep the frame, set the new glass with points, apply fresh compound, and let it cure for seven days before painting.

_Last reviewed: July 2026 · 7 min read_

A cracked pane leaks air, raises your heating bill, and looks bad from the curb. Whether a branch hit the glass or a settling frame stressed it, you can swap the pane yourself in a single afternoon. The job requires patience more than skill—removing old putty is tedious, and setting new glazing compound neatly takes practice—but the steps are straightforward for any wooden single-pane sash.

Okoniq Property Hub logs the date you replaced each pane, the glass dimensions, and the brand of compound, so you know exactly what worked when the next window cracks in five years.

What tools and materials do you need to replace a cracked windowpane?

You need five categories of supplies: safety gear, removal tools, the new glass, glazing materials, and finishing items.

Safety: Heavy leather gloves, safety glasses, and a dust mask. Glass shards and old putty dust are sharp and irritating. Lay a drop cloth below the window to catch debris.

Removal: A putty knife (stiff blade, 1–1.5 inches wide), a heat gun or hair dryer to soften old compound, needle-nose pliers to pull glazier's points, and a wire brush or scraper for the rabbet (the groove that holds the glass). If the putty is rock-hard, a gentle pass with the heat gun at 6 inches distance softens it without scorching the wood.

New glass: Measure the rabbet—not the broken pane—in both directions, then subtract ⅛ inch from width and height to allow expansion. Most hardware stores and glass shops cut single-strength (3/32 inch) or double-strength (⅛ inch) window glass while you wait for $10–$20 per pane. Bring your measurements in writing.

Glazing materials: Linseed-oil glazing compound (DAP 33 or Sarco MultiGlaze are common brands; $8–$12 per pint), a box of push-point glazier's points (also called diamond points or triangular points; $3 for 100), and a glazing tool or the flat edge of a putty knife to smooth the compound bead.

Finishing: Exterior primer and paint that match your trim, plus a small brush. The compound must cure for seven days before you paint it, so plan accordingly if winter weather is closing in.

Keep a roll of painter's tape on hand to protect the glass edge while you work the compound into place, and a damp rag to wipe fingerprints off the pane before the compound cures. If you're replacing multiple panes, buy compound in a quart and cut all glass at once to save trips.

How do you safely remove the broken pane and old putty?

Start by taping the cracked glass with masking tape in an X pattern—this holds shards together as you pry. Wearing gloves and glasses, gently tap the pane from the outside with a rubber mallet or the handle of a screwdriver to loosen it. Lift out large pieces carefully and drop them into a cardboard box lined with newspaper.

Once the glass is out, use the heat gun to warm a 6-inch section of old compound for 15–20 seconds, then slide the putty knife under it at a shallow angle. Work around the perimeter in sections—forcing cold putty breaks the wood or your blade. Pull the glazier's points with needle-nose pliers as you encounter them; there are usually four to eight per pane, spaced evenly.

After removing all compound, scrape the rabbet down to bare wood with a wire brush or the putty knife held perpendicular. Sand any loose paint and vacuum dust out of the groove. Inspect for rot: if the wood is soft or spongy, dig out the decay and fill with epoxy filler before proceeding. A sound rabbet is critical—compound won't stick to rot or flaking paint.

Wipe the rabbet with a damp cloth, let it dry, then apply a thin coat of linseed oil or exterior primer to the bare wood. This seals the grain and prevents the wood from sucking oil out of the fresh compound, which causes it to crack prematurely. Let the primer dry for an hour before setting the glass.

How do you set the new pane and apply glazing compound?

Roll a golf-ball-sized piece of compound between your palms to warm and soften it, then press a thin bead (about ¼ inch diameter) into the rabbet all the way around. This "bed" cushions the glass and seals the gap. Press the new pane into place, centering it so the gap is even on all four sides. Push gently around the edges—not the center—to squeeze excess compound out the back.

Insert glazier's points every 4–6 inches around the perimeter, midway up each side. Slide the point flat against the glass, then push it into the wood with the corner of your putty knife or a dedicated push-point tool. The tip should bite into the wood about ⅛ inch; the flat tab holds the glass. Two points per side (eight total) are enough for a standard 12×16-inch pane; larger panes need one every 4 inches.

Roll another rope of compound ¼ inch thick and press it into the angle between the glass and the wood frame on the exterior side, working around the perimeter. Use the putty knife or glazing tool at a 45° angle to smooth the bead into a neat triangular fillet that slopes from the wood down to the glass. The compound should cover the glazier's points and meet the glass at the same height as the interior rabbet edge—this keeps water from pooling.

Draw the knife in one continuous stroke per side if possible, rewetting the blade as needed to prevent drag. If the compound pulls away or looks lumpy, scrape it off and reapply—it's still workable for 20 minutes. Trim any excess from the glass with a razor blade once the bead is smooth, and wipe the pane with a damp rag before the compound skins over.

How long does glazing compound take to cure, and when can you paint it?

Linseed-oil compound takes seven to fourteen days to form a skin, depending on temperature and humidity. At 70°F and low humidity, seven days is usually enough; below 50°F or in damp conditions, wait two weeks. The compound should feel firm to the touch but not rock-hard—if you can dent it with a fingernail, wait longer.

Paint the compound within thirty days of application. If you wait longer, the surface oxidizes and paint adhesion suffers. Use exterior latex or oil primer followed by a finish coat that matches your trim. Lap the paint about 1/16 inch onto the glass to seal the compound-to-glass joint—this prevents water from creeping under the bead. A small angled sash brush (½ or ¾ inch) gives you the control to paint this hairline overlap neatly.

If you need to repaint the entire sash, do the compound first, let it cure, then prep and paint the wood and compound together. Never paint uncured compound—the solvents in paint will soften it and ruin the seal. For homes on the National Register or in historic districts, check local guidelines; some require traditional putty recipes or specific paint types.

Record the replacement date, glass supplier, and compound brand in your maintenance log. When a neighboring pane cracks in three years, you'll know exactly what you used and whether it held up. Tools like Okoniq Property Hub keep this timeline visible so you can compare product performance across windows.

What if the window has insulated glass or aluminum frames?

Single-pane wooden sash is repairable by any homeowner with patience. Insulated glass units (IGUs)—double- or triple-pane sealed assemblies—are not. If the seal fails or a pane cracks, you must replace the entire IGU, which requires removing the sash, measuring the unit, ordering a replacement ($100–$400 depending on size and Low-E coatings), and reinstalling it with new glazing tape or clips.

Most IGU replacements are best left to a glass shop unless you've done several and own a suction-cup lifter. The units are heavy (20–40 pounds for a typical 30×48 window), fragile at the edges, and expensive to reorder if you crack one during installation. If you decide to tackle it, measure the rabbet depth carefully—many newer vinyl or aluminum frames have a specific clip system, and ordering the wrong thickness means starting over.

Aluminum-frame windows with single panes use a rubber gasket or vinyl spline instead of putty. To replace the glass, you pry out the spline with a flathead screwdriver, lift out the old pane, drop in the new one, and press a fresh spline into the groove with a spline roller (the same tool used for window screens). The spline is $3 per roll at hardware stores and comes in several diameters—bring a sample of the old spline to match it.

For steel casement windows common in mid-century homes, the glass is often held by spring clips on the interior. Remove the clips, slide out the pane, clean the frame, and reverse the process with the new glass. These jobs are faster than wood-sash reglazing because there's no compound to wait for, but the clips can be stiff and the frames rust-prone—inspect for corrosion and prime bare metal before reassembly.

FAQ

How much does it cost to replace a single windowpane yourself versus hiring a glazier?

DIY costs $25–$40 for glass, compound, points, and primer. A glazier charges $150–$350 per pane including labor and materials, so you save $120–$310 per window. The job takes 90–120 minutes your first time, faster once you've done two or three.

Can you replace just one pane in a double-hung window, or do you need to remove the entire sash?

You can replace a pane with the sash in place if you have clear access to both sides. Tilt-in or removable sash makes the job easier because you can work on a bench, but it's not mandatory—many old double-hungs have fixed sash that you glaze from a ladder outside and stepstool inside.

What type of glazing compound should you use for exterior wood windows?

Linseed-oil-based compound (DAP 33 Glazing, Sarco MultiGlaze, or Abatron Master Glaze) is standard for wood sash. Avoid acrylic or latex "glazing caulk" on exterior windows—it doesn't harden properly and fails within two years. Traditional putty cures slowly but lasts 20–40 years when painted and maintained.

How do you know if the rabbet wood is too rotten to hold glazing compound?

Press a screwdriver tip into the wood. If it sinks easily or crumbles, the wood is too far gone. Dig out soft material with a chisel down to sound wood, treat with a wood hardener like Minwax, then fill the void with epoxy wood filler (Abatron WoodEpox or similar). Let it cure 24 hours, sand smooth, prime, and proceed with glazing. Skipping this step means the compound will fall out within a season.

Do you need to prime new glazing compound before painting it?

No, you paint the cured compound directly with exterior trim paint. The compound itself acts as a primer. Just make sure it's fully cured—seven to fourteen days depending on weather—before applying paint, and lap the paint edge onto the glass to seal the joint against water intrusion.

This is educational information, not professional advice. For historic windows, lead-paint concerns, or structural frame damage, consult a licensed contractor or preservation specialist.