Before you purchase your shower door, you must take proper measurements to ensure that it will fit. Unless you are an experienced shower door installer, this might sound like a daunting task - especially when you hear terms such as out-of-plumb and out-of-square. But don’t despair! We have all the information you need to conquer this task with ease. Once you finalize your wall material, you will then measure your opening and check that surfaces are level & plumb. (You can learn more about how to measure your space here).

Unless you have measured many wall spaces, you may not be well versed on how to determine how to find an out-of-square condition and what can be done. We're here to help.

To get started, let's do a vocabulary 101 course:



Out-of-Plumb conditions are non-level, vertical wall conditions.

Core Curb Plumb Color
Core Actual Curb Color



Out of Level conditions are non-level, horizontal curb, ceiling and or buttress wall conditions.


Filler - A piece of anodized aluminum that matches the desired finish and is installed behind a wall jamb or under a bottom track to plumb or level the surface. FIllers are recommended for any surface that is out-of-square 3/8" or more and they may be tapered. These are most commonly used on framed and semi-frameless shower doors.

Core Filler Color

Now it's time to check all surfaces (including top of buttress if applicable) and walls for level. To check the curb or wall of your opening for an out-of-level condition or an out-of-plumb condition, place a level of appropriate length on the curb. Any out-of-level dimension that is out of level 3/8" or more, a tapered filler is recommended.

*Note: Heavy glass will be cut out-of-square, so no filler is required.

Once you figure out the specific out-of-plumb/out-of-level conditions that you have, you will need to determine which fillers you'll need to install your shower door. Based on your shower door configuration, here are instructions to guide your filler installation.

The filler supplement for a pivot-hinged shower door will look like this: Click here for PDF

The filler supplement for a sliding shower door will look like this: Click here for PDF

The filler supplement for a Door & panel shower door will look like this: Click here for PDF


If you are unsure which filler you need, please don't hesitate to call our technical support line at 1800-45BASCO or by filling out our Contact form here.

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