RELIABILT Door Trim
RELIABILT door trim and casing that frames interior and exterior door openings for a finished look.
RELIABILT door trim (casing) frames the perimeter of door openings, covering the gap between the door frame and the wall. Available in primed MDF and finger-joint pine, in 2-1/4" and 3-1/2" widths. Sold in 7ft lengths (enough for one side of a standard door) or as complete door casing kits with pre-cut pieces. Priced from $3 to $12 per piece. All profiles come primed and ready for paint.
Door trim is one of the most visible finish elements in any room. Replacing damaged or mismatched casing is an affordable way to refresh the look of a space without replacing the door itself. Pair trim with matching baseboard for a cohesive finish.
Casing Styles
| Colonial | Curved profile with a subtle ogee shape. Traditional look. The most common casing profile in American homes. 2-1/4" wide. |
| Craftsman / Flat | Flat, square-edged profile. Clean, modern look. Works with shaker-style doors. 2-1/4" or 3-1/2" wide. |
| Ranch | Rounded edges, simple profile. Casual, unobtrusive. Common in 1970s-2000s construction. 2-1/4" wide. |
Match your door casing profile to your baseboard moulding profile for a cohesive look throughout the room.
How to Choose RELIABILT Door Trim
Each side of a door opening requires one piece of trim at least as long as the door height (typically 80"). The top requires one piece as wide as the opening plus the width of both side casings. For a standard 32" door, plan on two 7ft side pieces and one 38" header piece per side of the wall. Double that for both sides of the opening.
Match your casing profile to the architectural style of the home. Colonial profiles suit traditional homes, flat/craftsman profiles suit modern and shaker-style interiors, and ranch profiles match mid-century or casual spaces. Consistency matters; use the same profile throughout the house.
All RELIABILT trim comes primed and ready for paint. Buy trim and paint at the same time to keep the project moving. For stain-grade applications (natural wood finish), choose finger-joint pine rather than MDF, as MDF does not accept stain well.
Buy 10-15% more trim than your exact measurements call for. Miter cuts create waste, and you may make mistakes cutting angles. Having extra material on hand prevents a second trip to the store mid-project. Leftover trim stores flat and can be used for future repairs.
Key Installation Steps
Start with the header piece across the top of the door opening. Cut 45-degree miters on each end. Then cut the side casings with matching 45-degree miters at the top and square cuts at the bottom where they meet the floor or plinth blocks.
Apply wood glue to the miter joints before nailing. This prevents the joint from opening up when the wood expands and contracts seasonally. Use a brad nailer with 1-1/2" to 2" brads, nailing into the door frame and the wall studs behind the drywall.
After nailing, fill all nail holes with lightweight spackle or wood filler. Caulk the seam between the trim and the wall with paintable latex caulk. Sand the filler smooth, then prime and paint the entire casing for a seamless finish.
Common Problems and Fixes
| Miter joints open up | Wood and MDF expand and contract with humidity changes. Apply wood glue to the miter joint before nailing. If the gap has already appeared, fill it with paintable caulk, smooth with a wet finger, let dry, and touch up with paint. |
| Trim pulls away from wall | The wall is not flat. Use a brad nailer to pin the trim closer to the wall, then fill any remaining gaps with paintable caulk. Do not force the trim flat with screws, as this can crack MDF. |
| MDF swells at the bottom | MDF absorbs moisture from floor cleaning. Seal the bottom cut edge of MDF trim with primer or wood glue before installation. If already swollen, replace the affected piece and seal the cut edge of the new one. |
Long-Term Care for Door Trim
Caulk all joints between trim and wall, and between trim pieces, after installation. Re-inspect caulk lines annually. Shrinkage cracks and seasonal movement open small gaps that collect dust and look untidy. Re-caulk and touch up paint as needed.
Clean painted trim with a damp cloth and mild soap. Avoid abrasive cleaners that dull the paint sheen. For scuff marks, a melamine foam sponge works well on semi-gloss and gloss painted surfaces without damaging the finish.
If trim is in a high-moisture area (bathroom door frame), monitor the bottom 6 inches for signs of swelling or paint peeling. MDF is especially vulnerable to moisture wicking from the floor. Apply an extra coat of paint or primer to the bottom edge as a preventive measure.
When repainting a room, do not skip the trim. Freshly painted walls next to dingy, scuffed trim makes the trim look worse by contrast. A semi-gloss or gloss paint on trim is easier to clean and more durable than the flat or eggshell finish used on walls.
Frequently Asked Questions
What tools do I need to install door trim?
A miter saw (or miter box with hand saw) for cutting 45-degree angles, a brad nailer or hammer with finish nails, paintable caulk, and wood filler. A miter saw makes the job significantly faster and more accurate than hand cutting.
Should I use MDF or finger-joint pine trim?
MDF is cheaper, perfectly smooth, and ideal for painted applications. Finger-joint pine costs slightly more and can be stained or painted. For bathrooms and high-moisture areas, finger-joint pine resists moisture better than MDF. For most painted interior doors, MDF is the practical choice.
Can I install trim without a brad nailer?
Yes. Use 4d or 6d finish nails and a hammer. Pre-drill through MDF to prevent splitting. A brad nailer speeds up the job and reduces the risk of splitting, but it is not strictly required. Construction adhesive combined with a few nails is another option for lightweight MDF trim.
Door trim is part of the broader moulding and trim line. Install after your prehung door is set. For the bottom of the wall, add matching baseboard moulding. See installation tips for miter cutting guidance.