Installing Crown Moulding on a Sloped Ceiling

Old 10-12-14, 08:17 AM
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Installing Crown Moulding on a Sloped Ceiling

A room in my home features a sloped ceiling. The builder’s trim carpenter installed crown moulding throughout every room in this house except this one and it has always bothered me.

After I modeled the room in a CAD software, it quickly became apparent to me why he skipped this room: the corners--it's impossible to join moulding at corners where three none-perpendicular surfaces intersect.

Take a look at the images below. This is the room. Has anyone seen a technique (e.g.: transition cuts, blocking, crown pendants, etc...) to mitigate the problem of trimming along sloped ceiling that works in an aesthetically pleasing way?

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Name:  Fancy Room Trim Study - Corner A.jpg
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Last edited by lothian; 10-12-14 at 08:53 AM.
Old 10-12-14, 09:03 AM
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You will get more input from other woodworkers.

Crown can be installed in this room. It's very difficult (for me) and I've installed a lot of crown.

You will need a good/very good compound miter saw and crown molding tables or crown molding calculator. The formulas are scientific.

Here's a link to a website I found where you can look at the basics.
I don't have any affiliation with this site. It looks like they try to sell a few items to aid in installation, but it also looks like a lot of free information and I found it useful and honest.

Cutting crown to a ceiling angle
Old 10-12-14, 10:59 AM
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You need to add a transition piece to the corner to adjust for the different angles of attack. Here is a website that explains what needs to be done. You already have the angles so half the battle is done. There will also be some trial and error. Gary Katz Online

You can also use premade blocks to make the job a little easier. You basically would make straight cuts and flush up to the blocks.
Old 10-12-14, 12:32 PM
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You cannot transition from a slopped ceiling to a level ceiling with the same trim piece. That link czizzi provided does have one trick for doing inside corners, but nothing for outside except adding a block. To to the transition and have it look perfect, you need two different size crowns that are designed for that exact situation.
Old 10-12-14, 12:37 PM
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Always remember, too any trim angle must be equal on both sides. Determine the angle of drop, either mathematically or with trial pieces, and divide in two. Otherwise you will have unwanted uneven tails on the molding.

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