Now that fall is upon us we are all trying to find ways to save on our energy costs. If you have a cracked or broken window or the old glazing has fallen out it’s time to fix the problem. This How-To will help you tackle the job. Re-glazing is an easy and inexpensive job that will give you an airtight, watertight bond. To make the window look like a pro did the job will take patience. The good thing is that glazing compound is very forgiving, just remove the putty and re-apply.

Finished window with all new glass.

(A) Glazing compound, comes in two sizes (B) Hammer (C) Chisel (D) Hack-out knife (E) Window points (F) Angled putty knife (best to use for glazing) (G) Putty knife (H) Small pry bar if you don’t have a hack-out knife or chisle (I) Glazing Compound tube to use in a caulking gun, best to use for metal windows. If replacing glass in a metal window use metal glazing. You will need to lay an 1/16” of putty down before placing the glass into the window.

When removing broken glass always wear heavy gloves and safety glasses. Work from the top of the frame toward the bottom, and use pliers to wiggle glass shards free from the putty. Work on the exterior of the window if possible, since the putty around the glass is on the outside of the window.

For upper story windows work from the inside. To remove the window from the frame you’ll need to remove the mouldings around the front of the window. To remove the back window take out the spacer that holds the back window in. Be careful not to mar the wood because you’ll be re-using the trim when replacing the sash back in the frame. Use a putty knife to separate the moulding enough to place a flathead screwdriver in to get a better bite on the wood. For safety issues never remove a upper story window from the outside. With larger glass it will be easier to work on when the sash is removed and placed on a flat surface.

With the help from Mark Wambold, owner of Acme Glass Company, Inc., we worked on one of my windows in his shop. I had to repair this window and when making the repairs I had to remove all the glass. I asked Mark what it would cost to repair a broken window. He said it depends on how big the window. A 2’x 2’ window could cost around $50-$100 based on time and materials. By doing this yourself you could save some money. So let’s get started.

Tip: Use duct tape to hold the broken pieces of glass together as you remove the old putty.

Skill Level One hammer: Novice Five hammers: Experienced

With a hammer and chisel or hack-out knife chip out the old putty working left to right, taking care when you come across the old points. Keep the chisel an 1/8” from the glass when working. If the wood starts to split change direction until the putty is removed.	Go back over and remove left over putty and smooth any rough spots until you have a flat surface. If you gouge the wood you’ll have to lay a thin (1/16”) bead of putty so that the glass has a flat surface to lie on.	After all old glazing has been removed, measure the top and bottom of the opening(s) and use the shortest dimension and subtract 1/16″. Have all glass cut to size.
Lay the glass in place. Do not force the glass into the opening. There is a flat side and an L-shaped side to the window points. Lay the flat side down, using a screwdriver or glazing knife, push and wiggle the point until it holds the glass snug. Smaller glass uses one point per side, larger glass uses two.	Like above, work putty in the palm of your hand to heat it up and roll it into a snake, keeping the thickness uniform. If you are fixing one pane, average size (8″x10″) buy the smallest can of glazing compound. The product has a short shelf life.	Apply the putty working left to right, bottom to top forcing the putty into all the gaps. Apply all the putty at one time. After you’ve applied all the putty take your glazing knife and apply pressure with your right index finger and use your left hand index finger to guide the knife along the sash. Keep the knife 1/8″ away from the glass. When you reach the corner make a beveled edge. Now repeat the process keeping the knife clean. With each edge you will get better. If by chance you waver you can remove the putty and start again. Keep working until you get a smooth look.
Check from the other side of the window to make sure you can’t see the glaze. To remove the putty that can be seen past the wood adjust the angle of your knife and repeat the stroke. Let the glazing set-up for three to four days until a skin develops over the putty. Paint with oil-base primer and when it dries paint your final color coat.