Learning Center » Windows

How to Measure Glass for Window Replacement

Measurement is the most important part of window replacement. So, whenever you need to replace your window glass because it is old, broken – you will need to know how to measure glass for window replacement.

The measurements need to be exact, just as they need to be when you replace the entire window. When you buy new glass, it needs to fit precisely in the frame of the window, or you’ll experience drafts and higher heating bills due to improperly placed window glass.

With that in mind, let’s take a look at what you need to do to get it right:

Step 1 – Remove the Old Glass and the Sash

To measure the glass, first, you need to remove the old one. Use leather gloves for protection and apply some masking tape in a crisscross pattern on both sides of the glass to ensure it doesn’t break. If the glass is already broken, carefully remove all the pieces and clean the frame properly. 

If the glass is whole, you will also need to remove the sash on the window. The sash holds the glass in place, and the glass cannot be removed without removing the sash first. You can do this with a screwdriver or a pry bar. Make sure you clean the frame afterward of all the adhesive, glazing, or any other debris that’s left. You won’t be able to make proper measurements if there is any debris remaining inside.

When it comes to glass in windows, you will have to measure the surrounding frame, but you still need to measure the thickness of the glass because your replacement will need to be of the same thickness. Plus, it should be of the same type. That’s why it’s best to take a piece of the glass with you when you go to buy a new one. Alternatively, you can contact a professional service that can easily determine the best type for you and deliver it to your home. 

Step 2 – Do the Measurements

Measuring needs to be exact, which is why it needs to be to the nearest 1/16 of an inch. To do it properly, you need to measure the full interior of the frame. Start with the top and the bottom and record the numbers. They should be the same, but it’s important to check.

Now do the same for both sides of the frame and record the numbers again. 

When you have the measures, you need to subtract 1/8 of an inch from the smallest measurements on both the width and the height to account for the contraction and expansion that will take place in the frame. It swells from heat and contracts from cold, making these variations necessary, or the glass might break when it’s installed.

Check all of your measurements at least once again to make sure you’ve made no mistake. 

The Bottom Line

If you follow these instructions, you are unlikely to make any mistakes. You now have the proper fit for your window glass. If you need more help, or if you’re looking for high-quality windows, schedule a no-obligation free in-home estimate with 1-800-HANSONS, and we’ll be happy to assist you.

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