Do It Yourself Installation: Quick Guide To Cutting Crown Molding

This article targets beginners and gives a concise description of cutting crown moulding. Tip for a quick and easy install.

Cutting crown molding is baffling at first. The reason is that it appears so similar to base molding and other types of flat molding. Crown molding, however, does not lie flush against the wall or ceiling.

What we see when we look at crown molding is essentially the hypotenuse of a hollow right triangle, the right sides being the wall and ceiling forming the 90 degree right angle. Furthermore, in a corner, the top edge must be longer than the bottom edge by a forty-five degree angle or you will be left with a v-shaped gap at your joint. Demonstrate this effect to yourself by holding up two scrap pieces in a corner. You will find that to cut any corner joints the molding must be cut 1) at a forty-five degree angle from top to bottom making the top longer, and 2) at a forty-five degree angle from outside to inside. On an outside corner, the outside of the molding must be longer than the inside. Conversely, on an inside corner, the outside must be shorter than the inside. Luckily, miter saws are designed for these types of cuts. The hard part is knowing which way to place the molding in the saw and where to angle the blade.

The materials you will need for this project in addition to all the crown molding include a tape measure, a pencil, a miter saw, maybe a little bit of sandpaper and some paintable caulk.



The first step in any cutting process is to measure and measure twice. Crown molding measurements are always marked on the back of the piece. To cut the piece flat, place it face down in the miter box, knowing which is the top side and which is the bottom. It never hurts to mark this information on the back of your pieces, and it can save you a whole lot of frustration. Place your saw blade both at a forty-five degree angle to the table of the miter box (the part parallel to the floor) and at a forty-five degree angle to the fence of the miter box (the part perpendicular to the floor).

The grooves are provided in the miter box for this purpose. If you are cutting an inside corner, your saw blade must be angled toward the part you are keeping and always with the top longer than the bottom. Conversely, if you are cutting an outside corner, your saw blade must be angled away from the part you are keeping and always with the top longer than the bottom. Practice on a few scraps by making model inside and outside corners.

You may want to sand off very rough cuts. However, sanding too much, especially on the visible edges, will increase the gaps a great deal, so avoid sanding if possible. When you are through, you may notice slight gaps in your joints. This is not necessarily due to mistakes on your part. It is highly likely that your walls were not flush ninety-degree angles to begin with. This is due to settling or original discrepancies in construction. The easiest way to remedy this problem is by filling in the gaps with paintable caulk before painting.

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