How to Install Wood MoldingUpdated: Feb. 15, 2023
Extraordinary results with ordinary moldings
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Tip 1: Combine moldings for extra drama
I’ve installed miles of trim over the years, most of it in old houses, where I’ve encountered every conceivable shape, size and combination of wood molding. I’ve learned a lot in the process, but I’m still discovering new tools and techniques that make trim work faster, easier and better. Here are a few tips—some classic techniques and some with a modern twist—that’ll help you do a better job on your next trim project.
I love looking around old houses to see how wood moldings are combined to create baseboards, casings and cornices. I’ve even been surprised when removing old moldings to discover more layers than I originally noticed. The builders knew the advantages of combining small wood moldings. In addition to allowing endless possibilities for customization, smaller moldings are easier to cut and install than large moldings, and allow more flexibility on wavy or irregular walls. Plus, you can often achieve a great effect for less money by combining small wood moldings. I made the decorative ceiling cornice shown above using moldings I found at a home center.
The best way to plan wood molding combinations is to get your hands on some short lengths of molding and play around with them. Many full-service lumberyards have wood molding samples available. At home centers, you may have to purchase short lengths of each molding you’re considering, or ask for scraps. Learn how to do wood trim work on your own.
Tip 2: Inspect before you buy
Wood moldings can vary quite a bit in looks and quality, so it pays to examine them closely when you’re picking them out. It’s not as critical if you’re installing trim that will be painted, but for stained moldings, there are several things to watch for. Make sure moldings that will be close to each other have a similar grain pattern and that the wood is about the same tone (Photo 1). Chatter from shaper blades is another common problem to pay attention to (Photo 2). Although you can’t avoid chatter marks entirely, choosing wood moldings carefully can keep them to a minimum and significantly reduce your sanding time. Also watch out for “snipe,” gouge cuts near the end of the molding that are caused by the molding machine. That 10-ft. stick of molding you need may not give you a full 10 ft. of usable molding.
Tip 3: Put the pinch on miter joints
I recently ordered four miter clamps and a special pliers-type tool to install them and am amazed at how well they work. These handy little clamps are basically bent spring steel with sharp points that grab the moldings and squeeze them together. They’re perfect for holding small pieces of mitered trim together while the glue dries and for clamping crown molding miters while you pin them together. They’re also great for picture frame assembly. Our clamps are from Collins Tool Co. (collinstool.com; about $29 for the four clamps and special pliers), but other brands are available.
Tip 4: Spice up your project with reveals
Like every other rule, this one has many exceptions. But in general, when I’m combining wood moldings, or adding moldings to plain boards, I offset the parts so that the edges aren’t perfectly aligned. The exposed band of molding or board is called a “reveal.” Creating reveals has two big advantages. First, it allows a bit of flexibility, since the two edges don’t have to be perfectly aligned. Second, reveals look better in most situations.
The typical method of creating a reveal is to set back the edge of the molding from the edge of the board as shown here. However, an equally effective method is to allow the molding to protrude. Some reveals are set by tradition. Door and window casings, for example, are usually moved about 3/16 in. from the edge of the jamb. In other cases, you’ll have to trust your eye to determine the right amount.
Tip 5: Attach small parts with super glue
Mitered returns are tough to attach. They’re usually too small to nail unless you have a micro pinner. I’ve tried attaching small parts with wood glue, but often the moisture from the glue causes the thinnest part of the trim to warp before the glue dries. Here’s a tip I learned from a trim carpenter. Get some cyanoacrylate adhesive (CA) and activator, also known as “super glue.” You may be able to find a kit of CA that contains an activator at home centers, but a sure source is a woodworking store like Rockler. Go to rockler.com and search for “super glue” to find a wide variety. I like the medium-body CA. Spread a thin layer of CA on one piece of the molding and activator on the other. Then just press and hold for a few seconds. It works like magic, forming a strong bond unbelievably fast.
No Framing—No Problem
Once in a while, you may need to attach moldings where there’s no framing behind the drywall to nail into. For example, if you’re making frames on your wall out of wood moldings, it’s likely that one of the vertical moldings won’t have a stud behind it. The solution is to apply a thin bead of panel adhesive or construction adhesive and then tack the molding to the wall with a nail gun. For a better grip, shoot a pair of nails next to each other and at opposite angles so they form a wedge. If nails alone won’t hold the molding, press it tight with 1x2s wedged against the opposite wall or the ceiling to hold it until the adhesive dries.
Tip 6: Use nearly invisible nails
I was talking to John Frost, a local cabinetmaker, about how he installs wood moldings. After giving me a bunch of good tips, he said, “And of course you know about micro pinners.” Actually, I didn’t. John explained that a micro pinner is a finish nail gun that shoots super-thin 23-gauge pins. He uses a micro pinner because the small-diameter pins leave smaller holes that are almost invisible after you fill them. Plus, the tiny pins allow him to nail very small parts without splitting them as thicker pins might.
There are several brands of micro pinners ranging in cost from $120 to $330. The more expensive models drive pins up to 2 in. long. You’ll find micro pinners at home centers and online.
Tip 7: Add an auxiliary fence
I asked a cabinetmaker friend if he ever adds a fence to his miter saw, and he said, “Absolutely, always” An auxiliary fence has several advantages. It reduces the gap under and behind the molding to only what’s needed for the blade to fit through. The small gap helps prevent splintering on the back of the board and keeps small cutoffs from dropping through the fence and getting flung by the blade. You can also use the saw kerfs in the fence to help you line up your cut.
An auxiliary fence needs to be accurate but not fancy. I like to build fences from MDF because it’s straight, stable and inexpensive. Another good choice is 3/4-in. plywood. Make the back of the fence as tall as possible without letting it interfere with the motor housing or blade guard. If you need several short pieces cut to the same length, make the fence long enough so you can attach a stop. Be sure the bottom and back are exactly perpendicular and that you don’t put fasteners where the blade will cut. If you own a plate joiner, use glue and biscuits to join the back and bottom—no need to worry about hitting fasteners. Attach the auxiliary fence with screws through your miter saw fence.
Tip 8: Create original designs with SketchUp, a computer program
For this article, I worked on SketchUp, a drawing program from Google, to design a fireplace mantel and simple wainscot and window trim. I used moldings that I found at a home center and a local full-service lumberyard. The SketchUp model and some of the building details are shown here. I’ve been dabbling in SketchUp for a few years but still have plenty to learn. What I like best about this versatile 3-D drawing program is how quickly you can learn the basics and create useful drawings. You’ll be drawing 3-D shapes in minutes, and be able to draw a simple bookcase with a few hours’ practice. I use SketchUp routinely to design sheds, build bookcases or just work out a tricky building detail.
Get a copy of SketchUp by going to sketchup.google.com. Then click on “Download Google SketchUp.”
DIY Success Story
I built a new mantel and surround for the fireplace in my den. I decided to combine a number of different design ideas and customize it exactly as I wanted it. I used marble tile, various size pine boards and several types of wood molding, all from my local home center. The total cost was less than $500. FYI, I’m not a professional woodworker or builder.
— Allan Shaw
Required Tools for this Project
Have the necessary tools for this DIY wood molding project lined up before you start—you’ll save time and frustration.
- Brad nail gun
- Miter saw
- Super glue (with activator)