How to Assemble Your Door Frame

Your door and frame arrive flat packed: two long boards (the legs), one short board (the header), and the hinges already screwed on. Putting the frame together takes about 15 minutes with a hammer and a handful of nails. Here is how, step by step.

What you need

  • A hammer (or a drill, if you prefer screws)
  • Six 2" finish nails, or six wood screws
  • A measuring tape
  • A pencil
  • A clear, flat spot on the floor
  1. 1

    Get to know your three boards

    Clear a spot on the floor and set your three boards out. The two long boards are the legs. One of them is the hinge leg: it has the hinges already screwed on. The other is the latch leg: it has the opening cut into it for the door latch. The short board is the header, and it is already cut to the exact length, so there is nothing to trim.

    The three frame boards laid out on a floor: the hinge leg with two black hinges, the latch leg, and the shorter header board.
    Two legs and the header. The hinges come already screwed on.

    All three boards stand on their narrow edges, just like in the photo, and they stay on their edges for the whole build. Never lay them face down.

  2. 2

    Find the top and the bottom

    The frame has a top and a bottom, and it matters. The top is the end the header joins across. The bottom is the open end, which sits on the floor when the frame goes into the wall.

    How to tell which end is the top: measure from each end of the hinge leg to the nearest hinge. The end that reads about 8" is the top. This works no matter how many hinges your door has.

    ~8" longer top end bottom end the end nearer a hinge is the top
    The hinge leg seen from the side. The top hinge starts about 8" from the top end; the bottom hinge sits much farther from its end.
    Which side faces out? The smooth primed face of each board goes into the doorway. Primed means the wood already has its base coat of paint on it. If a face has shallow grooves running along it, that is the back of the board, and it ends up hidden against the wall.

    Now stand the two legs on their edges with the hinges and the latch opening facing across at each other, exactly how they will sit in the finished frame. Bring both top ends together at the end where the header will go.

    Do not build it upside down. If the header goes on the wrong end, the hinges end up at the wrong heights and the door will not hang right. Check the hinge spacing before you nail anything.
  3. 3

    Set the header on top of the legs

    The header sits on top of the two legs, covering the end of each one completely, with the outside edges lined up flush. It is already cut to the exact length, so there is nothing to trim.

    Check it: the header should measure the width of your door plus 1-7/16". With the header in place, its ends sit flush with the outside faces of the legs, and its top edge sits level with the edges of the legs. Flush means perfectly even, with no lip you can feel when you run a finger across the joint.

    header leg leg nail down through the header the header covers the top end of each leg
    The header sits over the top ends of both legs, flush at the outside edges.
    Check twice before fastening. Both hinges and the latch opening should face into the frame, and the header should cover both leg ends with the edges flush.
  4. 4

    Nail the corners

    First, mark where the wood is. At each corner, take a pencil and trace the outline of the leg's end onto the top of the header. Once the header is sitting on top, the leg is hidden underneath, and the outline tells you exactly where the wood is down there.

    Then nail inside the outline. Each corner gets three 2" finish nails, driven straight down through the header into the end of the leg, all of them inside your pencil outline: one near each edge and one in the middle. A finish nail is a thin nail with a very small head.

    Do one nail per corner first. Drive a single nail into each corner, then check that the corners are still flush and the header still covers both leg ends fully. When everything looks right, come back and drive the other two nails in each corner.

    Brace the boards before you swing. Boards standing on their edges tip and slide when you hammer. Push the outer edge of the header up against a wall so your hammer blows push into the wall, and have a helper or a heavy weight hold the leg steady.

    If the wood wants to split, drill small pilot holes first. A pilot hole is a small hole you drill before the nail goes in so the nail does not split the wood. Screws work too: use 2" wood screws with pilot holes.

    top of header three nails per leg: one near each edge, one in the middle
    You are looking down at the top of the header. The dashed boxes are the two legs underneath, one at each end. The nails go down through the header into the legs, one near each edge and one in the middle.
  5. 5

    Stand your frame up

    That's it, the frame is built. When you are ready to install, stand it up and place it into your rough opening, which is the framed hole in the wall where the door goes.

    The open bottom end will flex a little when you move the frame. That is normal: nothing holds the legs at that end yet. The frame gets held perfectly straight and square when it is fastened into the wall.

    The fully assembled white door frame: two legs joined by the header, with the hinges already mounted on the hinge leg.
    The finished frame: two legs, one header, six nails.

    Please note: this guide covers building the frame only, not hanging the door in it.

Questions at any step?

Get in touch and we will walk you through it.