Framing Door Openings: Cased Doors

Framing door openings includes a cased opening which is a doorway with no door in it. To trim the opening out, follow these steps:

The pieces that go inside the opening need to be solid wood so that no ply shows. A standard 2x4 wall is 4 and a half inches thick after the sheetrock is installed.

When framing door openings:

STEP 1: Measure the thickness of the wall at the opening.

STEP 2: Rip the inside pieces one-eighth inch wider than the measurement.

STEP 3: Sand off any saw blade marks.

STEP 4: Install the top piece against the door header. Make the piece the full width of the opening and shim the piece to make it level. Don’t just accept that the door header is level. Make sure that the piece “hangs out” a little on both sides of the opening.

STEP 5: Install the two side pieces. Cut them full length for a tight fit and shim them to make sure they are plumb. Don’t just accept that the door frame is plumb. This is very important if you will add bi-fold doors later. Make sure that the pieces “hang out” a little on both sides of the opening.

STEP 6: Measure the width of the opening remaining between the two side pieces you installed, at the very top of the opening.

STEP 7: Cut a 45 degree miter on one end of your casing material. The long end of the miter will be on top, and the short end of the miter will be on the bottom.

STEP 8: Cut your casing material a half inch longer than the opening dimension. This dimension is from the short ends of the miters on each side. The total length of the piece will depend on how wide the material is.

STEP 9: Install the casing piece on top of the opening. Center the piece across the opening. Raise the piece up off the edge of the opening an amount equal to the amount of space on either end past the opening. By making the piece a half inch longer than the opening, you create a “lip” or “space” called a “reveal”. You want to make the reveal the same across the top and down the two sides. Fasten the top piece near the middle, not near the two ends yet.

STEP 10: Measure the length of the two side pieces, including the reveal amount that the top piece has been raised.

STEP 11: Install the two side pieces, making sure to keep the reveal correct. Start at the bottom and fasten in place, coming up and fastening every 12 inches or so.

STEP 12: When you near the top, pull the end of the top piece and the end of the side piece together tightly and make sure you have a good fit. While holding the ends together, fasten both pieces near the corner.

STEP 13: Repeat the process for the remainder of the trim.

Now you have learned about framing door openings. Return from Framing Door Openings to Home Building Mentor

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