PFJ vs. MDF trim: what are the differences?

It’s said that the devil is in the details, and I feel like this is entirely true because a small finish can ruin what could have been a beautiful project. I’ll give you an example.

When I purchased my 1969 home a few years ago, every room needed painting badly. I chose beautiful beachy colors and the whitest white paint I could find (do you know how many hues of white there are?) for my trim and baseboards. I knew it would look gorgeous. Turns out, I was wrong. The brightest white I found had a pinkish tinge to it, which did not go well with the soft aqua I used on the walls. I didn’t compare them in the store, because they were purchased at different times.

This may be a strange example when talking about PFJ and MDF trim, but again, the devil is in the details. Both PFJ (finger jointed pine) and MDF (medium-density fiberboard) are common choices for contractors when finishing a room and its trim. There are some major differences between the two, and you must be aware of those differences before selecting your trim.

PFJ vs. MDF trim: what are the differences?

Below, we’ll look at what PFJ and MDF are, their differences, and which would work better for you in your home. Most importantly, we’ll look at what trim is, what it’s usually made of, and whether PFJ or MDF makes for better trim.


What Is Trim?

Let’s start with a basic question, what is trim? If you’ve come this far to question whether MDF or PFJ is better for trim, you likely already know the answer to that. However, did you know that there are several types of trim? Trim tends to be a blanket term for any of the casings added around the floors, doors, and windows. There are more kinds of trim than you likely realize, and many of these are more about adding flourish to your design than for functionality.

Crown molding: This is the stuff you see at the top of a room that helps the wall and ceiling join more beautifully.

Baseboard: We see this at the bottom of the drywall providing a proper seal to fill the gap between the drywall and the flooring.

Wainscoting: This type of trim is a larger decorative piece of wood (often plywood) that’s added to the drywall. It typically takes up the upper or lower half of a wall and is about 36 inches high. You may also hear this referred to as “bead board,” which is typically vertical lines.

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Chair rail: Originally used to protect the wall from the backs of chairs, the chair rail runs along the wall horizontally. It should be placed at the height of the room’s chairs. Check out these incredible chair rail ideas!

Picture rail: These pieces of trim were used to hang pictures without adding holes to walls. If hung properly, they still can be used for this purpose. This trim is typically placed a foot or so below the ceiling.

Picture frame molding: Similar to wainscoting, picture frame molding is purely decorative and takes up a large portion of the wall. Smaller pieces of trim make up a square frame that provides architectural flair to the room.

Casing: Casings are what we typically refer to when we are discussing trim. Casings are the pieces that go around windows and door frames. Unlike many pieces of molding, this is functional as well as decorative. These pieces cover the gap between the drywall and the frame of the window or door.

Corbel: These pieces are typically L-shaped and stick out from the wall connecting vertical and horizontal spaces, such as a square archway between rooms. These are often seen as decorative pieces on the outside of stone buildings. Its purpose is to help distribute weight but is often used as decoration in trim work.

Stool: This is what we call the “windowsill” in most areas. This is the larger flat wood set on top of the actual window sill. It is notched on the ends to extend beyond the window casings. My cat, and likely yours, likes to sit on these.

Apron: This is another piece of the window casings. This is the piece that sits just below the stool against the wall. It’s the bottom casing for the window.  The stool/windowsill and the apron go hand in hand. The top is called the head casing, in case you were curious.

Okay, you now know most of the important trim work that you’ll find in an average room. While medallions, rosettes, and other intricate filigree can be added, we’ll stick to the basic trim found in most houses for the rest of this article: casings and floorboards.

What Is MDF?

Medium-density fiberboard (MDF) is a newer product in the construction game. You may have seen it before in prefabricated furniture or even at the home improvement store. I first used it when building additional shelves in my pantry. Because I planned to paint the MDF, and I was on a tight budget, it seemed my best option. Let me explain why.

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Many people who don’t know what MDF is may scoff and claim that it isn’t really wood, and they would be wrong on that guestimate.

Companies that make MDF use all types of wood to create the MDF. Wood chips, pulp, sawdust, and scraps are ground down into a fine flour consistency. This wood dust is then cleaned, sifted, and added to a resin and other chemicals to create a very thick paste. This paste is run through a high-temperature roller, which presses the mixture together tightly and dries it.


The look of MDF is similar to cardboard. Depending on the wood used, it may be darker or lighter, but it is usually about the color and look of cardboard. A dark tan to light brown, there are small imperfections and flecks in the wood, but there are no knots or large defects. Since there is no natural grain in the wood, it cannot be treated like a piece of pine, so it should be painted.

Because it is made of so much material, it is denser than wood and plywood. This also makes it harder than some woods. With enough pressure applied to the MDF, it will buckle under the weight, so it was something I had to take into account when putting heavy cans on it in my pantry. MDF is also up to 25% cheaper than wood for projects, like trim and shelves. For these reasons, I believed it was perfect for my needs in the pantry.

What Is PFJ?

PFJ is a bit confusing in name – PFJ does not seem like the appropriate acronym for finger jointed pine. However, this is because while PFJ is typically referred to as “finger jointed pine,” it actually stands for “primed finger jointed.” It is also sometimes referred to as a “comb joint.”

PFJ is a great step forward in the construction game because it allows you to use a piece of wood that would not be strong enough to withstand its length in some cases.

See, PFJ is a process used by lumber yards to take smaller pieces of wood and put them together to make a larger/longer piece of wood. To do this, the pieces of wood have the edges cut similar to a comb’s teeth. These teeth are the exact opposite on each end so that they will lock together like a puzzle piece with other finger-jointed wood. These pieces are then glued together to make a stronger bond that will create what looks like one piece of wood.

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PFJ, sometimes also called PFP, is typically made from pine wood. However, the “P” may also stand for poplar, which is a popular choice for trim and baseboards. Poplar is often seen as a harder wood than pine, though both are very inexpensive softwoods. Since these are softer, they do not work as well for high-abuse areas.

Which Is Better for Trim?

This is a loaded question that can cause arguments between contractors. Whether you choose MDF or PFJ in your home project really depends on your budget and needs. When I was making shelves for my pantry, I focused on strength and cost. When selecting trim, you’ll want to consider the look of each, the ease of installation, and possibly the budget. What works best for you, not contractors?

The table below should help you decide what is more important for your project.

Look Looks like very hard cardboard. It is basically plain and brown. During the finger-jointing process, all knots are removed leaving you with only the look of natural wood. The zigzagging joints can be quite obvious depending on the wood match.
Cost MDF tends to be a bit cheaper than PFJ. Because PFJ is a natural wood product, it costs more than MDF.
Strength MDF has a hard outer casing that protects the trim from getting dented. However, the edges and corners are weaker that PFJ Since PFJ is made from softer woods, it can easily dent when hit. However, it is consistent all the way through.
Stain/Paint MDF can be painted, but its composition does not allow it to be stained. If the PFJ is primed, it cannot be stained. If it is raw, it can be both stained and painted.
Installation Use a nail gun to install since the hard exterior of the MDF makes hammering difficult. Makes very clean cuts with a saw. Installation of PFJ is simple, you can use a hammer and nails or a nail gun.
Hazards Because of the chemicals used (sometimes formaldehyde), this can be dangerous to cut. It also kicks up a dust storm every time it is cut, so wear safety goggles. Wood can easily rot and warp if not properly sealed.