Exterior Painting Tips: How To Reglaze A Window

If you're like many people with an older home, you might still be sporting single-pane wood windows and storms.  While they may not be quite as energy efficient as their insulated double-pane counterparts, not everyone has the money in their budget to replace them.  

The good news is that if you keep the drafts out by keeping your storm windows -- as well as the individual panes of glass in the sashes themselves -- in good shape they'll perform pretty well for you.  The problem is that old wood windows are a maintenance item, but most people don't take a good look at their condition until they're painting the house -- which is as good a time as any to make those needed repairs.

In this week's exterior painting tips article we'll discuss the proper way to reglaze a window pane.

Out With The Old 

Remove the entire window sash in need of repair, if possible, so you can work on it while it's laying down rather than trying to work on it in the frame.

Replacing The Glazing Only

To remove the old glazing you'll need a heat gun to soften the cured putty.  Cover the surrounding panes and glazing with aluminum foil to keep from affecting them.  If the glazing is in need of repair but the glass itself is still intact, lay a piece of metal step flashing onto the glass to deflect the heat and keep from cracking the pane with the heat gun.

Apply heat until the putty is softened then with a 5-in-1 tool remove the old putty.

Replacing The Glazing & The Glass

Wear gloves and eye protection when removing broken or cracked glass.  Remove the glazing as described above, and using your 5-in-1 tool carefully remove the old metal glazing points from the wood that secured the glass in place.

Use your heat gun to continue to remove any glazing that lived in between the glass and the frame.  Once all of the putty has been removed from the wood channel where the new pane will lay, apply some exterior wood primer to the bare wood areas and allow it to dry.

If you're replacing the glass, have the new piece cut to the exact size of the old one that you removed, or if the old one was too damaged to take a measurement, then measure the channel when the the new one will go and have the new piece of glass cut to 1/8" smaller than your measurement in each direction.

In With The New

Step 1:  (If you're only replacing the glazing and not the glass you can skip to Step 5)  Knead a ball of new oil-based glazing compound in your hands until it's softened then roll it between your hands to make a rope.  Lay the rope of compound along the channel where the glass will sit and press it firmly into the channel.  Make sure you use plenty of compound and don't worry if you're afraid it will make a mess, you can clean it up later.  It's more important to make sure you have plenty of putty in the channel.

Step 2:  Using gloved hands for protection, press the new window pane into the putty and into place, gently wiggling it back and forth as you press so it can seat itself until the glass is nearly touching the wood in the channel -- about an 1/8" from making contact with the wood.

Be sure there are no bare putty spots between the glass and the wood channel.  If there are, pull the pane back out and add more glazing compound.

Step 3:  Once the glass has been bed into the compound, lay a metal glazing point flat onto the surface of the glass and, Using a stiff putty knife or 5-in-1 tool, carefully push the point into the wood frame centered along one of the edges -- gently rocking it back and forth until it is buried into the wood.  

Repeat the process on the opposite side of the pane, then again on each of the other two sides.  For larger panes of glass, the glazing points should be installed evenly-spaced every 4-6 inches around the perimeter of the glass to hold it firmly into place.

Step 4:  Flip the sash over and scrape away the excess compound that pushed out while inserting the glass.

Step 5:  Knead another ball of putty into a rope about 3/4" thick and press it into the gap where the glass meets the wood channel, all along the perimeter.  

To smooth out the compound, take your putty knife at about a 45 degree angle between the glass and the outer face of the wood surrounding the glass.  While applying downward pressure, pull the putty knife along the length of the compound starting at one corner and working your way to the next, removing all of the excess.  

Try to keep a crisp line in each of the four corners.  Keep your putty knife clean with each pass to avoid dragging the compound or pulling it out of the joint.

Allow the putty to dry for about 1 week until it's stiff.  

Step 6:  Wipe off any oily residue from the surface of the glass with a dry cotton rag, then apply an oil-based exterior primer to the putty overlapping it just slightly onto the glass to seal down the edge.  

Step 7:  Once the primer has dried you're ready to topcoat it with a good 100% acrylic latex paint.

Step 8:  After the paint has dried you can come back with a razor blade to scrape off any excess paint/primer from the glass.

Reglazing damaged old wood windows will not only improve the look of your paint job, but also give you the added benefit of increased energy efficiency.  It can be a time-consuming project to complete but it's well worth the time and effort.  Make it a practice to walk around the house and inspect your window panes to see if they're in need of attention before you start any exterior painting project.

If you're located in the Greater Pittsburgh or Western Pennsylvania areas and would like some assistance with your exterior painting project please give us a call at 724-898-2446, visit our 'Contact Us' page, or click on the button below to have us contact you. 

 photo by:  George Hodan / CC BY CC0 1.0