How to Install Polystyrene Crown Molding

Video Transcript

Video Transcript

You know, I really love architectural millwork and molding. It adds detail, character and elegance to just about any room. Now I'm fortunate to have a good bit here in the living and some in the family room.

But this is one room, the master bedroom, where I haven't put up any crown or cornice molding and I think it would look really nice in here. So I'm gonna do it. But I've kind of set up a challenge for myself. I want to work alone and I want to do this project in the very simplest way possible.

A little bit of exploration on the Internet led me to Creative Crown Molding of Dallas. Now here, I found an intriguing option to the usual solution. So I placed an order. The whole thing arrived in a box only four feet long and weighing just a couple of pounds.

Now this cornice molding is not wood, but polystyrene. It's lightweight, easy to handle, I can cut it using regular woodworking tools, and get this, it requires no nails or screws to put up. I'm going to start in a corner. So I’ll cut a 45-degree miter on one end -- and square up the factory cut on the other. Instead of screws and nails, this molding will be attached using construction adhesive.

First I trim the end off the nozzle, then puncture the inner seal. On the backside of the polystyrene trim, I place strips of adhesive, about half-an-inch wide and a couple of inches long. I lay one of these about every six to eight inches.

Now I take the very manageable four foot section and simply press it onto the wall. The adhesive holds it in place. Then I square up the ends of the next section, apply adhesive to it, and press it in place, making sure the ends of the two pieces align with each other.

Trim, apply adhesive, press on the wall. It's really that simple – and fast -- to put this molding up. When I get within four feet of the corner, I first cut a miter on the far end of the next section. Then place the cut end into the corner and mark the point where the two pieces overlap.

Now, I can make a simple straight cut. To insure I'm exactly on the mark, I like to nibble away at the material, moving it closer and closer to the blade until I'm in just the right spot. This way, I end up with a piece that’s almost always an exact fit.

Now I can begin the same process on the next wall as I work my way around the room. In most cases, the construction adhesive will provide enough tack to hold the lightweight molding in place as it dries. If necessary, strips of blue painter's tape can be used to prevent any slippage and make doubly sure that cut ends and joints stay exactly in position. The tape can be removed in a few hours. Once the adhesive has set, I apply acrylic painter's caulk to the joint between the molding and the ceiling and tool off the excess with my finger. After that, I fill and smooth the joint between the molding and the wall.

The caulk also works well to fill any small gaps in the miter joints. To conceal irregularities where the molding sections abut each other, I apply a bit of spackle with my finger -- then smooth off the excess with a putty knife.

Once dry, the spackle could be sanded smooth with number 320 sandpaper. Now, I like to fold or roll the paper to fit the molding contours. Now it's time for a bit of painting. I like to use a spout like this one. It helps to keep paint out of the can rim when stirring and pouring.

When doing trim, I prefer to transfer the material into a smaller container that I can easily hold in one hand. Polystyrene molding should have at least one coat of primer before finish painting. I prefer two, with a light sanding in between.

Now, if you've got a steady hand and plenty of patience, you can cut the paint onto the molding into the wall and ceiling. Or you can place strips of painter's tape on the wall and/or ceiling and be a lot freer with the brush strokes.

I usually remove the tape shortly after I finished applying the paint to lessen the possibility of peeling the paint away, along with the tape. Another big time saver is to paint the molding before you put it up. You can paint in a comfortable position and not have to worry about being careful around the edges. You will though, have to plan on a bit of touchup at the joints.

Now, I'm always gonna be a fan of wood trim, but I have to say, the polystyrene has a lot going for it. It's lightweight, easy to install and relatively inexpensive.

So I guess what it comes down to is choosing your weapon. Will it be a nail gun or a caulking gun?

Learn how to install lightweight polystyrene crown molding by yourself; watch a video of step-by-step instructions.

Architectural millwork and molding can add detail, character, and elegance to just about any room, but it can be difficult to put up on your own. A great innovation has made crown molding easy enough for one person to do alone.

The polystyrene molding used in this project was provided by Creative Crown Molding.  You can click here to go to their website.

For this project, I did cut miters on the corners.  However, you can eliminate the need to do that by using these corner blocks also available from Creative Crown Molding and other suppliers.

This molding came in eight foot sections which means, not only can a section easily be handled by one person, but it can be conveniently shipped.