Things You'll Need:
- Tape measure
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Step 1
Examine the exterior side of your entrance way. Most homes will have a door installed within a frame, as well as casing or trim surrounding the frame. The casing that is used on the exterior side of the home is known as brick molding and is generally wider than the frame itself. When measuring for your storm door, you will use the dimensions of the brick molding, not the frame itself.
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Step 2
Measure the width of your brick molding at three separate locations. Measure a few inches from the top and bottom of the opening, as well as somewhere near the middle. On most doors, these three measurements will vary slightly. Use the smallest of these three measurements to determine the width of your storm door.
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Step 3
Determine the height of the opening. Take this measurement at one side of the opening and then again at the other side. The shorter of these two measurements will give you the height of your storm door.
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Step 4
Calculate the thickness of the opening. This is the dimension from the face of the brick molding to the face of the frame and is usually about 1 inch. This measurement will be used when determining the thickness of your storm door.
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Step 5
Purchase your door based on the height, width and thickness values you measured in Steps 2 through 4. Most storm door manufacturers offer doors that work within a range of opening sizes. Find the range that fits your opening and choose a door meant for that size range.
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Step 6
Look for a storm door with a Z-bar extender when fitting storm doors into over-sized openings. Storm doors generally come in standard widths to match average door openings. If your frame is larger, a Z-bar extender will allow you to fit a too-small door into a large frame. Most storm doors have this bar available as an option, or you can purchase a Z-bar at home improvement or hardware stores.
