Replacing a broken pane of glass in a historic window or door is not a difficult task and does not require any expensive tools. This brief tutorial will walk you through the process step by step

1. Acquire supplies and tools

2. Prepare the work area
3. Remove the door or window
4. Remove the broken glass pane
5. Clean up the frame
6. Install new glass
7. Replace glazing
8. Reinstall door or window

Of course, not all doors and windows are constructed the same as this example. Before you go and tear your house apart, please read through this entire project description and determine whether your door or window matches.

Acquire supplies and tools

The tool list for this project is relatively simple. Only one specialty tool is necessary and should be available from your local hardware store for under $10.

Tools

• Tape measure (for measuring the glass)

• Hammer
• Pliers
• Scraper (various sizes)
• Small chisel
• old stiff putty knife (that you don't mind dinging up)
• Glazing knife (putty knife with an angled end)
• Paint brushes
• Cleaning supplies
• Saw horses or other stable work area
• Leather gloves
• Safety glasses

Supplies

• Replacement glass (tempered or safety glass if required)

• Glazing
• Glazing points
• Tack cloth
• Rags
• Boiled linseed oil
• Paint
• Plastic sheeting

If the broken pane is in a door a stairway window, or a window that is low to the floor, building code may require tempered or safety glass to be installed. Tempered glass can be purchased from a glass supply store, but must be cut to size by the supplier. Tempered glass is more expensive than standard float glass.

This project assumes no major repairs are required to the actual window or door. Rebuilding a window or door is a much more involved project that will be covered in another article.

Prepare the work area

Because old glazing has a habit of flying everywhere, and it is possible you will break the pane of glass you are removing, this project is best done outside.

Before removing the window sash or door for this project, determine whether or not there is lead paint. Failure to follow lead-safe work practices could create lead hazards for you, your family, and visitors to your house.

Whether or not there is lead paint, lay out 6 mil plastic below your work area, extending out at least several feet on either side to collect debris from the project. This plastic will collect the old glazing, any broken glass, and paint chips that fall. It can be rolled up and thrown away after the project is complete.

Set up sturdy saw-horses to work on.

Remove the door or window

This particular example is in a door. To remove a door, simply pull the hinge pins out and remove the door from the frame. If the hinge pins stick, use a squirt of lubricant such as WD-40 and pull them out with pliers.

You can also grab the head tightly with the pliers and tap upwards on the pliers with a hammer.

Remove the broken glass pane

Safety first during this stage: Wear leather gloves and safety glasses. If the glass pane shatters, you could end up with shards in your hand or even worse, your eye. You should also wear long pants and closed shoes in case glass falls down.

Depending on the condition of the existing glazing, this step could be very easy or very time consuming. On this particular door, the glazing was still relatively stable. Some pieces were difficult to remove. I had to alternate between a small chisel and a putty knife to pry it out.

The glazing is actually just a weather barrier. The pane of glass is typically held in place by small pieces of metal called glazing points that stick into the wood frame. Glazing points are spaced about every six inches and must be removed before the pane of glass can be taken out. They can be sharp, so remove them with a putty knife.

Clean up the frame

Use a small scraper to clean up any remaining glazing, shards of glass, and paint from the frame.

Then wipe it down with a tack cloth to remove any remaining dust. Once the bare wood is clean, it is time apply boiled linseed oil to the exposed wood. Applying boiled linseed oil to wood extends its life and helps paints and glazing adhere to the wood. Never store used linseed oil rags. If stored improperly, they may spontaneously ignite. They should be washed or incinerated.

Install new glass

Once the opening is prepared it is time to install the new piece of glass. There are certain circumstances in which tempered or safety glass is required by code, generally in places where people are more likely to impact the glass.

Kneed a bead of the glazing putty in your hand and press it into the rabbet (on what will be the inside of the door or window).

Gently press the glass in the opening and wiggle it to seat it into the putty. Don't worry about excess putty at this point - it will be trimmed later.

Install glazing points by pressing them into place with the glazing knife or a putty knife. You should place them about six inches apart.

The glazing points should be inserted until the flange rests against the wood frame. The glass pane should be secure with no movement or rattling.

Replace exterior glazing

Window glazing is a putty that hardens over several weeks. As mentioned before, it is not "structural" and is intended as a weather barrier - the glazing points hold the glass in place. the Glazing should be painted to match the window after 10 to 14 days.

First grab a handful of glazing and work it in your hands until it is warm and pliable.

Then roll out a snake about the diameter of dime and press it into place along one side of the glass.

Press the glazing into place with the glazing knife at about a 45 degree angle.

The glazing should look uneven and lumpy at this point. It will get trimmed off and smoothed next. After the glazing has been pressed into place, run the glazing knife along the edge at a 30 degree angle in one continuous move from corner to corner. This will create a smooth surface and trim off the excess glazing compound.

Don't worry if your edges are uneven or the surface isn't smooth - this takes some practice. The good news is that glazing compound is a very forgiving material. You can always remove the mistake and start over, add more to even things out, or try another pass with the glazing knife.

Corners take a bit of practice as well. To get a sharp corner, line the glazing knife up so the edge cuts into the corner at the angle you want. Jiggle it around a little to build a nice corner with the glazing compound, then drag it out in each direction to smooth out the surface.

Proceed with all sides of the window pane. It may be necessary to revisit the first sides. This is perfectly acceptable, and the glazing compound will stay workable for some time. If it cools down too much, it will start to "grab" at the glazing knife. If this happens you may need to pull it out and rework it in your hands.

Trim off the excess putty on the interior side of the glass with a clean putty knife.

Reinstall door or window

Congratulations! You have replaced a broken window pane! Now reinstall the window or door. You will need to paint the glazing in ten to fourteen days, after it has skinned over and hardened. Don't leave it unpainted and exposed to the weather for too much longer.

Prime with an oil-based primer followed by a latex paint.