Next to giving your interior walls a fresh coat of paint, investing in new casings, baseboards, and crown moldings is one of the best value added ways of improving your home.
That being so, there are some basic finishing rules to follow, along with a few installation strategies, that’ll help make working with MDF moldings all the more easier.
If you haven’t shopped for finishing trims in the last 15 years or so, the market has almost totally gone MDF (medium density fiberboard). You can still buy the finger-joint, clear pine, oak, and poplar species of casings and baseboards, but with the fashion trend still leaning towards painted moldings, as opposed to staining, MDF delivers the biggest bang for the buck.
Simply put, MDF is far cheaper in price, and is available in far more profiles, than traditional paint grade moldings such as finger-joint pine or poplar. Because the MDF product consists of sawdust and various glues, some home builders, fearing the off-gassing or VOC (volatile organic compound) element of a manufactured product, choose solid wood.
Actually, all wood species omit small doses of formaldehyde in their natural state. However, today’s MDF moldings are purchased factory sealed with a primer, which basically eliminates the off-gassing or VOC factor. As a result, the off-gassing or VOC concern regarding MDF moldings is old news, dating back about 20 years.
If you’ve worked with real wood moldings in the past, and are looking to install your own MDF casings and baseboards today, there’s one major factor that separates MDF from the popular finger–joint pine moldings of the 70’s and 80’s, and that’s the fact MDF moldings accept a nail the same way a cat accepts being tossed into a pool of water.
MDF moldings don’t like regular finishing nails, or being hammered, or being pre-drilled, and due to being so hard and somewhat brittle a product, the moldings’ edges can dent easily if over-handled.
Therefore, if you’re about to take on the task of installing MDF, be sure to buy, rent, or borrow, a pneumatic finishing nailer. What about pre-drilling the MDF, then tapping in a finishing nail, you may ask? Although a useful technique with hardwoods, a finishing nail tapped into MDF (even if pre-drilled) will cause the surface material to puff out once the nail head embeds the surface, creating a bump, which will essentially look lousy. MDF moldings absolutely need to be air nailed, and there’s no getting around that.
Rules to follow when choosing a casing and baseboard? One, they should match each other, of course, and two, the casing always needs to be thicker than the base. The baseboard molding will in most cases be wider than the casing, but it should never be thicker.
Some folks choose a thicker baseboard, with the strategy that it will hide the expansion spacing required between a wall and the hardwood or laminate flooring, thereby saving on the need for a shoe molding. Please don’t commit this finishing faux pas. Too thin a casing, or even a casing that is the same thickness of the base, looks horrible. When these two moldings meet, the shadow line created by having the casing thicker than the base, is key to proper finishing.
If you absolutely can’t live with a shoe mold following the perimeter of the floor, or have fallen in love with a particularly thick baseboard molding, and as a result, are left with too thin a casing, consider using a back-band molding to beef up the thickness of the casing.
Next, pre-paint your casings and baseboards before installing them. This strategy simply takes advantage of gravity, given that it’s easier to paint a molding while it’s lying flat, than sitting up on a wall.
Finally, caulk the seam where the casing or baseboard meets the wall, but never the miter joint. Gaps in a miter or butt joint can’t be saved with caulking. If the joint’s not tight, accept the loss and cut it over again.