Before you nail any crown molding to the wall you need to do a little prep. First you need to locate all the studs in your walls and the ceiling joist. This is easily done with a stud finder. Make some light pencil marks that you can see as you nail your crown molding up.

Next you need to figure out which way your ceiling joists are running. This important because if for example you are installing crown molding in a square room you will only have nailers for the top of your crown molding on two of the four walls. Joists almost always run from the front of your house to the back, but take the time to be sure with your stud finder.

Now this leaves two walls where there is no nailer for the top of your crown molding. So you need to make nailers. You do this by holding a small piece of scrap molding against the wall and ceiling how it will be install. Notice there will be a triangle gap behind the molding. You need to make nailers the size of that triangle gap out of wood.I like to use 5/4” x 4” pine to cut my triangle nailers, but you can just use 2” x 4” also. Another easy way to find the size of your triangle nailer is to use a framing square as the wall and ceiling and place the crown molding in the square how it will sit on the wall and ceiling. Now you see the triangle gap and the square has the measurements right on it. Be sure to deduct at least 1/8” to 1/4″ off your triangle nailer measurement.

When installing crown molding the nailer doesn’t have to fit perfect behind the molding to work effectively. The last thing you want is the nailer forcing your molding not to sit flush against the wall and ceiling. So leave a little room.

Next install the nailers on the walls without ceiling nailers. Hold the nailer against the wall and ceiling and pre drill the nailer with a counter sink drill bit into the studs on the walls. Next use a 3” coarse thread drywall screw to attach to the stud.

Next you need a reference line on the wall at the height the crown molding should sit on the wall. I do this by taking a piece of scrap molding placing it against the wall and ceiling properly and then scribing a pencil mark on the wall at the bottom of the molding.

Now go around the room and make marks in all the corners and several points along the wall. You could also use a chalk line and mark the corners and then snap lines around the room. This can be a pain if you are by yourself and also messy if you are working in a room with furniture and carpet. Now your prep is done.

You now have located all your nailers in the walls and ceiling so when installing crown molding you know where to nail. Where there were no nailers you installed them and you also know how and at what height you want your crown molding to sit on the wall.

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