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Crown Molding Gap Ceiling

crown molding ceiling gap

Here's a crown molding gap at the ceiling. The red arrows point to the ugly gaps. See below how to avoid and fix them. Copyright 2018 Tim Carter

"Crown molding ceiling gap happens because the rough lumber behind the drywall shrinks. It can be prevented by nailing the ceiling molding to the ceiling allowing it to float up and down on the wall."

Why is There a Crown Molding Gap at Ceiling?

Ceiling molding, or crown molding, can pull away from the ceiling because the humidity inside a home is less in the winter months.

Charlie from Easley, SC has a crown molding gap where it meets the ceiling. I have the same issue at my own home.

It's important to realize he’s got ceiling crown molding in at least one room of his home and in the winter months a gap appears between the top of the crown molding and the ceiling.

He felt it was a temperature-change issue, and in some ways he’s correct. However, it’s important to realize the temperature in his home is very likely fairly consistent month to month. Perhaps it varies by eight to ten degrees.

Related Links

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CLICK HERE to get FREE & FAST BIDS from local painters who can caulk the ceiling gap.

crown molding ceiling gap

This ceiling crown molding gap happened because the wall drops down in the winter from lumber shrinkage. Copyright 2018 Tim Carter

Does Rough Lumber Shrinkage Cause Crown Molding Gap?

Yes, rough lumber shrinkage is the cause of crown molding gap.

Crown molding ceiling gap happens because the rough lumber behind the drywall shrinks. It can be prevented by nailing the ceiling molding to the ceiling allowing it to float up and down on the wall.

Another key point is the outside temperature and humidity is much different in South Carolina during the year. As the air cools down during winter months, it holds much less humidity.

The lumber in Charlie’s, and my, house dries out and shrinks. This rough-framing lumber shrinkage is the source of our joint woes.

How Can I Fix Ceiling Molding Gaps?

You can fix ceiling molding gaps temporarily in the winter by caulking the crack. Do this when the gap is the largest and use the most expensive flexible caulk you can buy.

crown molding ceiling gap

This small piece of ceiling molding is affected just like long pieces. It's easy to do it right, but hard to repair. Copyright 2018 Tim Carter

How Can Crown Molding Gap Be Prevented?

The problem could have been prevented had the carpenters that installed the crown molding attached it to the ceiling instead of the wall studs. The foot of the crown molding would then just ride up and down the wall surface as the lumber expands and contracts with the change of seasons.

A simple triangular block of rough lumber that just about fills the void space behind the crown molding could have been nailed to the ceiling joists on two walls and blocking on the other two. The crown molding would then be nailed to this wood with the nails aiming up towards the ceiling.

crown molding nailing

Crown molding gaps at ceilings can be eliminated if you attach the crown molding this way. NO nails should enter the wall studs or top plate. Note the blue triangular block that is custom cut to fill the void behind the crown molding. Nail it to the ceiling joists or blocking in lieu of joists. Then nail the crown molding up through the triangular block into the ceiling. Copyright 2018 Tim Carter

Charlie’s best chance of fixing the crack without reinstalling the crown molding, a huge pain in the keister, is to caulk the gaps in the middle of winter when the gap between the molding and the ceiling is the greatest. I’m going to fix mine by using the most expensive caulk I can locate that has the greatest amount of long-term flexibility.

Six months from now the caulk seam may squeeze out of the gap a little bit, but come next winter if the caulk performs as expected, there will be no gap.

CLICK HERE to get FREE & FAST BIDS from local painters who can caulk the ceiling gap.

Fix Crown Molding Gap at Ceiling | AsktheBuilder.com
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Fix Crown Molding Gap at Ceiling | AsktheBuilder.com
You can caulk the crown molding gap, but the better fix is to make sure it's not nailed to the wall. Nail the molding to the ceiling.
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9 Responses to Crown Molding Gap Ceiling

    • Well, you can try to caulk the gaps when they're at their widest and hope for the best. The contractor was supposed to GLUE the miters and pin the two pieces together with cross nailing to prevent the wood from gapping.

  1. This problem along with the similar problem of cracks in the wall/ceiling joint are much more common in newer construction that uses trusses instead of stick built roof construction. The problem occurs because of the heavily insulated attic space, the insulation causes uneven heating in the truss, which will cause the upper part of the truss above the insulation to expand differently than the portion of the truss below the insulation. This will cause the bottom chord of the truss to rise in the middle in the winter and come back down in the summer, causing cracks in the ceiling or the crown molding cracks discussed. The solution to this is to use drywall clips that are installed before the dry wall is installed. The clip is nailed to the wall framing and the ceiling dry wall is slid into the clip, the dry wall is then fastened to the truss about 18 inches from the wall. This allows the drywall to flex winter to summer and prevents the ugly cracks from occurring.

    How many of you professionals out there are using dry wall clips? Apparently not many, as the last house I built the clips where special order from Lowes!

  2. Thank you, Tim ! for the specifications...and for ALL of your suggestions/recommendations. How much I, and we, value your wisdom, expertise, and humor ! Jim

  3. Thanks for the possible solution of redoing the caulk when it is cold. I am going to try that and see what happens. I am going to use a Sashco product called Big Stretch. If I remember I will let you know how it worked.

  4. Several years ago, a contractor installed crown molding, a chair rail, and wood around the two entrances in my dining room No gaps in the ceiling, but the mitered corners, one mitered chair rail, and the wood around the entrances in places need caulking. I also had another contractor install crown molding in my family room. The only gaps are in three mitered pieces, not the ceiling. One looks bad and I had the contractor caulk it before I paid him.

    The rooms still look good with the molding, and I am not going to do anything until they need repainting.

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