Q&A / 

Door Rough Opening Not Square

Don Sanders is pulling out his hair in Peculiar, MO.

It seems he installed a door in his shed and the rough opening wasn't square.

Here's what he sent to me:

"I installed an entry door in my shed.

The floor was level and the jack and king studs were level.

So why weren’t they square with each other?  If two objects are level, one vertically and horizontally, shouldn’t they be square?"

Here's my answer:

Don, first you're using the term level where you shouldn't.

Horizontal surfaces are checked for level.

Vertical surfaces are checked for plumb.

Let's go back in time to your high school geometry class.

A square or a rectangle has for 90-degree corners.

The top, bottom and sides of both shapes have straight lines.

The straight lines are mission critical.

In a square, the top, bottom and two sides are the exact same measurement.

In a rectangle, the top and bottom are the same measurement and the sides are a different measurement, but they are equal. 

For example, in your door rough opening which is a rectangle, the top and bottom might be exactly 38 inches, and the two sides are 83 inches.

Here are the possible problems and you might have two or more of these going on at the same time:

  • Your level is out of calibration
  • The vertical king and jack studs have a bow in them
  • The measurements are not exactly equal as stated above
  • The floor is not level
  • You have a sloppy vial where the bubble doesn't meet the lines on the vial making it hard to determine level and plumb. READ this past column about this issue.

Even if the rough opening is not square, because it's oversized you should be able to hang the door and get the door square making prudent use of shims.


Leave a Reply

You have to agree to the comment policy.