RELIABILT Window & Door Moulding
RELIABILT window and door casing moulding that frames openings. Colonial, craftsman, and ranch profiles.
RELIABILT window and door casing moulding frames the perimeter of door and window openings, covering the gap between the frame and drywall. Available in 2-1/4" and 3-1/2" widths, sold in 7ft and 8ft lengths. Same profiles as baseboard (colonial, craftsman, ranch) so they can be matched. $0.40 to $1.20 per linear foot. One standard door takes about 17ft of casing (two sides and a header).
How Much Casing Per Opening
| Standard Door | 2 legs (80" each) + 1 header (32-38") = ~17ft. Buy 3 pieces of 7ft casing. |
| Standard Window | 4 pieces (2 legs + header + sill casing) = ~14ft for a 36" wide window. |
| Waste Factor | Add 10% for miter cuts and mistakes. Better to have extra than to make a second trip. |
How to Choose Window & Door Casing
Width: 2-1/4" casing is standard in most production homes. 3-1/2" casing creates a more substantial, upgraded appearance and is common in homes with 9ft+ ceilings or traditional styling. Use the same width throughout each floor of your home.
Profile matching: Always match your casing profile to your baseboard. Colonial casing pairs with colonial baseboard. Craftsman casing pairs with craftsman baseboard. Mixing profiles in the same room looks inconsistent.
Material: Primed MDF is best for painted casing. It has no grain, takes paint smoothly, and costs less than pine. Use primed finger-joint pine in kitchens or bathrooms where moisture exposure is a factor.
Quantity: A standard interior door requires approximately 17ft of casing (two 80" legs and one 36" header). A standard 36" window requires approximately 14ft (four pieces). Always buy an extra piece per room for miter mistakes.
Reveal: The reveal is the narrow strip of jamb visible between the casing edge and the jamb face, typically 3/16" to 1/4". Mark this distance on the jamb before nailing casing. A consistent reveal is what separates professional-looking trim work from amateur installations. Use a combination square set to your reveal distance as a marking gauge.
Rosette blocks: If you want to avoid miter cuts entirely, use corner rosette blocks at the top corners of door casing. The casing pieces are cut square and butted into the block. This is a legitimate traditional trim style, not a shortcut, and works especially well with craftsman-profile casing.
Issues and Fixes
| Miter gaps at corners | Out-of-square door frames cause miter gaps. Adjust the miter angle by 1-2 degrees until the joint closes. Fill small gaps (under 1/16") with paintable caulk. Larger gaps require re-cutting. |
| Casing not flush with wall | If the door jamb protrudes past the drywall, plane or sand the jamb edge flush. If the jamb is recessed, add jamb extensions before installing casing. Casing must sit flat against both the jamb edge and the wall surface. |
| Nail pops after painting | Nails set too shallow will push back through filler. Sink finish nails at least 1/16" below the surface with a nail set, fill with lightweight spackle, sand smooth, and prime before painting. |
| Casing pulling away from jamb | The reveal (gap between casing and jamb edge) should be a consistent 3/16" to 1/4". If casing shifts, it was likely nailed only into drywall. Renail through the casing into the framing behind the jamb. |
| Uneven reveal | An inconsistent reveal (varying gap between casing and jamb) is the most visible sign of amateur trim work. Mark the reveal distance on the jamb before nailing using a combination square. Start at the top corners and work down, checking alignment as you go. |
Window and door casing is the most visible trim in any room. Take time to get reveals consistent and miters tight. The difference between good and great casing work is attention to these small details.
Long-Term Care
Cleaning: Dust casing with a dry cloth or vacuum brush attachment. Window casing collects more dust on horizontal surfaces (stools, headers). Wipe with a damp cloth as needed.
Caulk lines: Re-caulk the joint between casing and wall every 3-5 years as it cracks from seasonal expansion. Use paintable acrylic-latex caulk and smooth with a wet finger or caulk tool.
Repainting: Door casing shows wear faster than window casing due to proximity to hands and foot traffic. Expect to repaint door casing every 5-7 years. Use semi-gloss paint for durability and easy cleaning.
Humidity considerations: In kitchens and bathrooms, casing near sinks and dishwashers is exposed to steam and splashing. Inspect these areas more frequently and touch up any paint chips promptly to prevent moisture from penetrating the MDF core. Consider finger-joint pine casing in high-moisture areas for added durability.
Replacement timeline: MDF casing lasts 15-20 years under normal conditions. Replace if edges are crumbling, joints have permanently separated, or moisture has caused swelling. When replacing casing around windows, inspect the window stool (sill board) at the same time.
Frequently Asked Questions
Should door casing match on both sides of the door?
Yes. Both sides of a door opening should use the same casing profile and width. If two rooms have different baseboard heights, the casing still stays consistent. The casing belongs to the door, not the room.
Can I install casing without a miter saw?
A miter saw produces the cleanest cuts and is strongly recommended. Alternatively, you can use a hand miter box for small jobs. Another option is a butt-joint (or rosette-block) method where casing pieces meet square-cut at corner blocks, eliminating miter cuts entirely.
How do I case a window without a stool (sill)?
Picture-frame the window by running casing on all four sides with mitered corners at each corner. This is common in modern and craftsman styles. For a traditional look with a stool and apron, install a 1x6 appearance board as the stool, then case the top and sides with the stool extending 1" past the casing on each side.
Install after setting your prehung doors or new windows. Match profile to baseboard in the same room. See all moulding options.
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