We are preparing to tape and mud the 'inside corners' of a diagonal attic ceiling, where the short walls meet the ceiling. What is the best way to achieve a straight line? Is there a special tool we can use? Free-handing is not working for us. Our 90 degree trowel works fine for vertical inside corners, but of course the 'corners' we are trying to do are horizontal.


1 Answer 1


I've had decent luck not taping inside corners at all. Instead I've use a sanded caulk. The key is to have a nice sharp edge to work with where the two pieces of sheetrock meet.

But if you want to mud and tape, there are tools for that:

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They come in various angles, but most can adjust the angle merely by angling the handle yourself.

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