Rochester Door Co

When replacing a door or door frame, precise measurements are crucial to ensure a seamless fit. Here's a guide on how to measure a door opening like a professional:

Measure the height, width, and thickness of the door.
Note hinge pitching (distance from the top of the door to the top of each hinge) and strike location.
Recognize nominal vs. actual door size; commercial doors are typically undersized by 1/8" on each side and the top.
Measure hinge pitching on the frame, ensuring the top hinge's pitch is 1/8" larger than on the door.
Measure lock centerline locations on the frame, from the bottom to the center of the strike.

Replacing both eliminates the need to measure hinge pitching and strike locations.
Frame sizing is more about wall condition than the door.

Commercial hollow metal frames typically have a 2" face and various throat sizes.
The most common throat size for welded frames is 4 ¾".
Heights and widths of frames can be modified to accommodate different opening sizes.

Commercial hollow metal frames typically have a 2" face and various throat sizes.
The most common throat size for welded frames is 4 ¾".
Heights and widths of frames can be modified to accommodate different opening sizes.
For width or height, measure at different spots along the opening and go with the smallest measurement.

Rough opening should be approximately 1" larger than the nominal size of the frame on each side.
Example: A 3'0 x 7'0 knockdown frame should have a 38" x 85" rough opening.

Rough openings cut in concrete should be approximately ¼" larger than the nominal frame size on each side.

By following these steps, you'll be equipped to take accurate measurements for your door opening, ensuring a perfect fit for your replacement door and frame.

Opening Width (A): Add 2".

Opening Height (B): Add 1".

Example for a 3’0” x 7’0” door & frame:

A = 3'0" + 2" = 38"

B = 7'0" + 1" = 85"

Rough Opening Dimensions:

Optimal rough opening: 38" x 85".

Note for Fire Rated Openings:

For fire-rated openings, ensure drywall extends at least 1/2" into the frame.

(A): Measure the width of the opening and add 4-1/2".

(B): Measure the height of the opening and add 2-1/4".

Example for a 3’0” x 7’0” door & frame:

A = 3'0" + 4-1/2" = 40-1/2"

B = 7'0" + 2-1/4" = 86-1/4"

Rough Opening Dimensions:

The rough opening should be 40-1/2" x 86-1/4" for optimal fit.

Frame Outer Dimensions (O.D.):

The O.D. of the frame is 40" x 86", considering a 2" face around all three sides.

How to Measure a Door Opening for a Perfect Fit