I was recently told that the previous owners of our house used casing instead of the trim throughout the house. What is the difference between window casing and trim? Are there are got-yas that I need to be aware of because one was used and not the other?

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    I say window casing, you say window trim, someone else says case moulding, lets call the whole thing off! It's one of those cases where a picture would be worth a 1000 words, along with their explanation as to what they really meant. Mar 13, 2013 at 0:41
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    Either way, the trim/casing is mostly decorative. If it looks attractive to you and the insulation between the window and the wall isn't exposed then it is perfectly acceptable. Mar 13, 2013 at 1:28

2 Answers 2


Trim is a general term, often used to describe all types of molding and millwork.

Casing is a type of molding, typically used to trim the perimeter of windows and doors. Casing is typically less wide (tall?), but thicker than base molding.

11/16" x 2 1/4"

Base molding (or baseboard) is a type of molding, which is applied where the wall and floor meet.

Base molding
9/16" x 3 1/4"

Crown molding (or crowns) is a type of molding, which is applied where the wall and ceiling meet.

Crown molding
7/16" x 3 5/8"

I think what the person was saying, was that the previous owner used casing in place of base molding.

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    Not that there's anything wrong with that. Don't go ripping it up just because it's casing. It's not going to cause a problem. Mar 13, 2013 at 16:02
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    @ChrisCudmore - exactly. If it looks good, it was appropriate. Sometimes the effect you want isn't available in the naming of the trim that's available. Unless you're on TOH and can affort to have someone make custom planer blades, but then you'd better be redoing the whole house for historical restoration to justify the cost. Mar 16, 2013 at 18:46

You can always add a decorative strip to enhance the thickness of the casing if it bothers you that much but if it looks good, don't worry about it and leave it. It's for whatever look that pleases you. It's just different words they use in construction for certain decorative accents. It's like getting gels instead of a regular manicure.

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