How to Install a Door Frame

Installing a door frame correctly is the foundation of a well-functioning door. A plumb, square, and level frame ensures the door hangs properly, swings freely, and seals tightly. Here's how to do it step by step.

Types of Door Frames

• Pre-hung frame: Comes assembled with the door already mounted; easiest to install
• Knock-down frame: Three separate pieces (two side jambs and a head jamb) assembled on site
• Split jamb frame: Two-piece design that installs from both sides of the wall

What You'll Need

• Door frame (jamb set)
• Shims
• Level and carpenter's square
• Drill and screws (3" for structural attachment)
• Hammer and nails (for casing)
• Utility knife
• Measuring tape

• Mr. Pen Carpenter's Square 8×12" — essential for checking frame squareness at every step
• AikTryee Laser Level Kit — check plumb and level quickly and accurately
• Amazon Basics 8-Piece Wood Chisel Set — for trimming shims and fitting jambs

Step 1: Prepare the Rough Opening

The rough opening should be 2" wider and 2" taller than the door size. This gives room for the frame and shims. Check that the rough opening is plumb, level, and square before proceeding. Fix any issues now — they're much harder to correct after the frame is installed.

Step 2: Install the Head Jamb First

Cut the head jamb (top piece) to the correct width. Set it in the top of the opening and check it's level. Shim as needed and nail or screw into the rough framing.

Step 3: Install the Hinge-Side Jamb

This is the most critical piece. Set the hinge-side jamb in place and check it's perfectly plumb in both directions (front-to-back and side-to-side). Shim behind the jamb at hinge locations and nail through the shims into the rough framing. Check plumb after each nail.

Step 4: Install the Latch-Side Jamb

Set the latch-side jamb and check plumb. The gap between the two jambs should be consistent from top to bottom — equal to the door width plus 1/4" for clearance. Shim and nail in place.

Step 5: Check Square

Measure diagonally from corner to corner in both directions. If the measurements are equal, the frame is square. If not, adjust by pushing one corner in or out until the diagonals match.

Step 6: Score and Break Shims

Score protruding shims with a utility knife and snap them off flush with the jamb face. Don't cut with a saw — it can damage the jamb.

Step 7: Install Door Casing

Nail the decorative casing trim around the frame on both sides of the wall. Miter the corners at 45 degrees for a clean finish.

Step 8: Hang the Door and Test

Hang the door and check the gaps are even on all sides. A properly installed frame produces consistent 1/8" gaps at the top and sides.