Gaps in the Ceiling Joint with Crown Moulding

Troubleshooting a gap that appeared between architectural crown and the bathroom ceiling. February 16, 2014

I put in some crown molding in a bathroom about 6 months ago. After installation I prepped it for paint and lightly sanded and caulked where the crown meets the ceilings and walls and then painted. I was just there and there is now a space were the crown meets the ceiling. Any idea what caused this? Should I re-caulk and paint again?

Forum Responses
(Cabinet and Millwork Installation Forum)
From contributor M:
How big is the gap? If it's just a small gap, it's most likely from settling or maybe the crown had a high moisture content and dried, causing it to shrink a little. Did you nail the crown to wall and ceiling? Did you hit anything in the ceiling? The only thing I can suggest is for you to recaulk and repaint. That should do it. You shouldn't see any more gap. Use a good quality caulk.

From contributor L:
My guess would be that it is wood crown mould. Wood shrinks against the length, whereas MDF mouldings shrink with the length. One good thing you can do at the time of installation is use 16p finish nails to slightly convex the crown. Then when it shrinks it will still be on the wall.

From contributor M:
It is probably the roof trusses lifting in the winter. It will more than likely close up in warmer weather.

From contributor K:
Was it at the exterior or interior wall or both?

From the original questioner:
It is both interior and exterior walls.

From contributor K:
Then the guys who installed the sheetrock put a fastener within 18" of the wall on the ceiling (or used glue on the ceiling), which is causing the movement. The only way to correct that is to remove the fastener. That's not going to happen, so your only solution at this point is caulk/repaint. I mean, I guess you could go up into the attic and use a Fein Multimaster to cut the fastener from the truss (assuming you could find it), but chalk this one up to some caulk/paint and explain to the homeowner.

When we install crown on homes post-1990, we glue the top part of the crown only so it attaches with the ceiling and run caulk on the wall. Takes a lot longer for any cracks to appear and when they do they are only hairline to a max of 1/16" and people are usually ready to repaint by then. Make sure you cope the corners, though, or you will end up with cracks in the corners.

From Gary Katz, forum technical advisor:
Contributor K, excellent advice!

From contributor B:
You can use a magnet to find the fastener and remove it by backing it out if the sheetrock has been screwed, or drive it in all the way with a nail set if it's been nailed. Then you only have a very small hole to patch and touch up the paint. I often do this on the initial install when I see a somewhat sizeable gap between the ceiling and the crown.