Molding Installation

Many people think that cornice is very difficult to install. Others think it very simple because they saw the guy on T.V do it in half an hour. The truth is cornice can be done by the do it yourselfer, with the right tools and a little bit of patience. Please be aware that this guide is meant for the first time installer, so some of the terminology and things that come as second nature to professionals will be explained thoroughly. There are many schools of thought when it comes to installing cornice; this guide will teach you the method our installers use. It's not to say that the other ways are wrong but we find that this method works very well for us.

First we have to look for a large open floor area to cut; normally the garage. Our cornice comes in 12, 14 and 16 foot lengths; look for an area where you will be able to cut lengths of that size. We look for a spot outside otherwise the MDF dust will get everywhere. All cutting is done on the floor using a Compound Miter Saw with a 10 inch draw . The draw is the distance the saw arm can cut in one pull. Although the cornice comes in various widths up to 7 inches, the width of the cornice increases in direct correlation with the angle of the miter. The difference between a compound and a normal miter saw is that the compound allows you to make both a Bevel and a Miter cut at once. Cornice requires a two angled cut because it is installed onto the wall and ceiling on a 45 or 52 degree angle. Unlike baseboards which are installed flat onto the wall and only require a single angle cut (or a miter). The reason our installers cut on the floor is quite simple, the cornice is too long and moves too much to be cut accurately on a table.

Take out your Measuring Tape and start measuring the walls that are going to be finished. Measure as accurately as possible down to the closest 16th of an inch. Make sure you note the Inside and Outside Corners . To explain inside and outside corners, imagine a perfect square, if you are standing inside the square, you will only see inside corners. If you walk around the outside of the square all you will see is outside corners.

Before we begin cutting we must determine the correct angle using an Angle Finder . An angle should never be assumed, what looks like a 90 degree angle may be off slightly. Once the angle is determined use our Cutting Chart to set the compound miter saw in order to get a nice tight corner.

There is some prep work required, remove anything hanging on the walls, and clear everything approximately 30 inches from the wall in order for the ladders to fit. Your ceiling may have a stucco finish, do not concern yourself; the stucco doesn't need to be removed. Once you start to pin the cornice up on the ceiling you'll find that the stucco breaks off. The little gap that is visible will easily be covered by the paint able latex caulking that will be applied later.

In order to cut you will require a Compound Miter saw with a ten inch draw. Using the Angle Finder and our Cutting Chart you should be able to set the Bevel and Miter angles required to make the proper corner. We normally recommend that you make yourself small inside corner and outside corner samples before you begin cutting into the long lengths that will be installed.

Compound Miter Settings

45 Degrees
52 Degrees

This should allow you to visualize what each corner will look like before cutting. Now that we've cut a few pieces, it's time to pin them up in place. We will require a Compressor and a Pneumatic Finishing Nail Gun . The reason for the nail gun is simple, when set properly; the nail gun automatically counter sinks the nail heads about a ¼ inch into the cornice. This allows for an easier time when finishing (we'll get to that later). We normally have the compressor set to between 98 and 110 psi. Installers, who have never worked with MDF before, should test and adjust the air pressure as needed for their specific equipment. We find the best fasteners for the job are 15 - 18 gauge brad and pin nails approximately 1 ½ to 2 inches in length. We apply a pair of nails on both the top and the bottom of the cornice every 12- 16 inches in an "X" pattern. The "X" ensures that even if a joist wasn't caught with a nail the cornice will not fall down because the "X" creates a fastener in the drywall.

The placement of the nail on the face of the cornice plays an important part in the installation. If you look at the back of the cornice, you will notice that there are three flat sides to it. The two small angles are the parts that touch the wall and the ceiling. These two angles run along the entire length of the cornice and these are the two areas you should be aiming for when you begin nailing. You should always try to place the nail gun so that the nail head is hidden into a crease on the face of the cornice. Although the nail head is countersunk, the hole is visible sometimes even after we cover it and sand it, whereas in a crease, it disappears.

All corners should be glued using MDF glue which can be picked up at any of the large box stores. We don't use either white or yellow wood working glue because both of these glues remain slightly flexible, even when they are fully cured. That means that in time they will allow the MDF wood fibers to slip a bit. Manufacturers call this "creep". The solution is to use glues that will cure rock hard. Another thing to consider is that MDF is far more fibrous than solid wood and so using water-based glues will cause "swelling" at the joints. MDF glue is solvent based glue that allows a virtually invisible seam.

Joints are a little different than corners. Joints happen when you have a straight wall that's longer than the available lengths. There is a process that goes along with it in order for the joint not to come apart.

If a wall is 16 feet long, we will cut one piece 5 feet and one piece 11 feet. Never cut the wall into two halves, peoples eyes are always drawn to the middle of the wall and so any imperfections will be visible.
Do not use a straight cut to join the two pieces. Cut the two ends at 30 degrees to ensure a tight fit and to allow for a larger glue surface.
Find a block of wood that is approximately 8 inches in length and narrower than the cornice. Glue this piece to the end that is being joined, ensuring half of it is sticking out at the end in order for the next piece of cornice to be joined to it. Nail this piece of wood in from the front of the cornice. By both nailing and gluing, you ensure that this piece will never move.
Next, install the length with the block attached, to the wall.
Add a little glue to the face of the block and install the next length just as you normally would. After ensuring a tight fit, add a few nails to ensure the two lengths don't come apart.

After having nailed up all the lengths, we are ready to start the finishing of the installation. We use a paint able latex caulking to caulk the cornice to the ceiling and the wall. Apply a generous amount to all seams, when the caulking dries it tends to sink inwards. Go over the freshly caulked seams with your finger in order to get rid of excess caulking.

The nail holes, corners and joint seams should be sealed and filled with a Spackling Compound . Spackling is a plaster like material that is applied wet and is allowed to dry before being sanded off. It should also be applied generously. A fine (200 grit) sandpaper should be used to sand down the spackling in order to get a smooth finish. The nail holes can easily be filled with a finger and do not need to be sanded.

Do not paint the cornice before you install it, you will have to paint it again anyways after all the sanding is done.

Your cornice is now installed and ready to be painted. If you are thinking of painting the house please do yourself a favor and install the cornice first before you paint. Any professional painter will tell you it is easier and faster to paint the cornice before the walls. Due to the fact that we are trying to recreate plaster cornice, we suggest a flat white or at most an eggshell paint. Flat paints tend to hide imperfections better than a gloss or a semi gloss, which tends to show the brush strokes. Although we have seen cornice painted every color in the rainbow, we are trying to recreate the look of plaster which is traditionally a flat white. As a rule of thumb we suggest a glossy or semi gloss paint for Baseboards, chair rails, door and window casings and any other trim you or the kids can touch. The lower trims will more than likely get dirtier than the cornice ever will and so therefore you need a paint and finish that is easily cleaned.

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Installing Molding