How to Replace Broken Window Glass

Knowing how to properly remove and replace a broken window will save not only time, but also money, effort, and even injury. Removing and replacing windowpanes is not difficult; however, you must have the proper knowledge and skill to complete the job correctly. There is more to it than simply inserting a new windowpane and smearing putty. This article will teach you how to prepare glass, install glass, add the finishing touches, and replace the glass on doors.

Step 1 – Removing Broken Glass

To simply remove a cracked pane of glass, remove the putty in order to remove the broken glass. The next step is to remove the old putty from the window frame with wither a wood chisel, putty knife, or jackknife. Remove every trace of the putty.

Even if the windowpane isn’t a large one, use protective gloves when you remove the frame. After it is removed, place it on a flat surface. Then remove the broken glass. Gloves will protect your hands against cuts. Though monotonous, the simplest way to clear the pieces of a shattered windowpane is by plucking each single broken piece out one at a time.

Step 2 – Remove Any Putty

Use heat to soften the putty in stubborn areas. Run a heat source like a blow dryer along the putty ahead of your chisel to help the putty to pull away from the wood frame more easily.

Some putty may be extremely difficult to remove due to Glazier's points, which are small metal triangles driven into the frame beneath the putty. They hold the glass in place. Remove all the Glazier's points as you remove the putty.

Once you have removed all of the old putty and the glazier's points, use the point of the chisel or the knife to smooth rough spots in the wood frame.

Step 3 – Oil Older Frames

If you are replacing glass in an old window, use a small paintbrush to apply a heavy coat of linseed oil to all sections of the wood around the frame. Allow the oil to completely soak in before proceeding. Linseed oil is important because it maximizes the life of the putty, which holds the window pane in place.

Linseed oil on the frame prevents oil in the putty from evaporating or drying out too quickly. If you saturate the wood with linseed oil before applying new putty, it will remain pliable and last much longer.

Step 5 – Apply New Putty Layer

Next, apply a very thin layer of putty around the frame where the new glass will be set. Ensure that the base layer of putty is not too thick. This thin layer of putty provides a cushion for the new glass to be inserted in. This cushion prevents the air from leaking around the glass and buffers the wood and glass.

If the putty is too thick, it swells, smudges, and becomes visible at the periphery of your window pane, potentially impacting clarity and visibility through the glass.

Step 6 – Installing New Glass

Cutting

The replacement glass must be exactly the right size. Cut it to size with a glass cutter. Generally speaking, a window pane should be less than an inch smaller than the area it will fill. Insert the new windowpane into the frame carefully and press it firmly.

Placing

While it’s possible to hold the new pane in position with one hand and simultaneously use your free hand to insert Glazier's points every 4 inches on each side to firmly secure the pane, its not advisable. Instead, call over a friend for an extra set of hands. It is less risky that way.

A minimal amount of pressure should be used to insert the Glazier's points, and with a second set of steady hands, you’ll reduce the difficulty and the risk. The old pane already broke, don’t be reckless with this new one.

Tip: Having you and a friend each hold one side of the glass as you work, ensures it will fit properly.

Step 7 – Use Glazier Points

Lay each Glazier's point flat against the glass. Start them into the wood using the point of a putty knife. Use the glazing tool to drive the Glazier's points into the wood. Slide the glazing tool along the glass to eliminate the danger of breaking it.

Step 8 – Preparing Putty

Putty should be the consistency of dry and thick dough. If it is too stiff, thin it according to the manufacturer's recommended method. Use an old piece of glass as a kneading board to work the putty into the right shape and consistency.

Knead the putty until it is completely pliable and free of lumps. Then roll it into pencil-size strips. Take a roll of putty into your hands and applying it in one corner of the window frame. Lay the strip in the frame completely around the new piece of glass.

Once the putty is completely in place, smooth it with a putty knife using long, even strokes. Hold the glazing tool at an angle. Make sure the tool as cleans because any corrosion makes it difficult to do a smooth job.

Step 9 – Plan Your Putty Placement

Study the figure to learn the best way to apply putty to the frame. It should cover the Glazier's points. It should also be set at an angle so that it holds the glass firmly in place without showing from the opposite side of the window.

Step 10 - Finishing Touches

Refer to the label on the putty for painting instructions. You may be able to paint the putty right away. Whether you should wait to paint depends on the manufacturer's recommendations. Use at least two coats of exterior paint.

An simple paint coat can cover not only the putty, but also part of the glass. Don't worry about straight edges. Use a razor blade scraper to remove the excess paint from the glass.

Replacing Glass on Doors

Although most window glasses are held in position with putty, the glass on many doors is held in place with thin wood strips. Building codes in many areas require that safety glazing material be added to entrance doors.

If the pane of glass on a door is broken, you can remove and replace these wood strips without putty. Pry the strip on the long side with a screwdriver, putty knife, or some other prying instrument.

Always remove the long side first. After removing one strip, the others will come out easily. After the strips are removed, use a pair of pliers to remove the small brad nails or to pull them through the wood strips.

Information in this article has been furnished by the National Retail Hardware Association (NRHA) and associated contributors.