Install a cripple stud between the header and the top plate halfway between the king studs.
Build interior door frame.
Install the door inside the jamb frame by assembling the hinges.
This yields a stronger more stable door frame which has less tendency to warp or distort over time.
Then you can cut the bottom plate out after the wall is installed.
I build mine by laminating two pieces of 3 4 thick stock.
Then measure the height and width of the doorway you ll be installing the door in and mark the dimensions on the plywood.
Place the head jamb over the top ends of the side jambs.
Build the wall with a bottom plate running across the doorway.
Make a header by fitting two 2 x 8s around a 1 2 inch piece of plywood.
Most interior doors today are made from a material called masonite which is a kind of wood fiberboard that is steam cooked and pressure molded onto a thin wood frame to create a slab door that has an appearance of a door with rails stiles and panels.
When complete you should have a door frame without a bottom piece.
But they can be done with regular clamps too provided you have enough.
You will need to add 1 2 of plywood between the 2x4 s to get the right wall thickness of 3 1 2.
To make the door header the top of the door frame cut two 2x4s to the same length as the width of the original opening and nail them securely together.
This domestically produced pocket door frame includes the track installation hardware and instructions.
This is the actual thickness of a 2x4.
To make a door start by getting a 4 foot by 8 foot sheet of plywood that s 1 2 inch thick.
Cut the door header.
The builder s choice wood pocket door frame is the builder s choice wood pocket door frame is constructed from solid hemlock and is conveniently pre assembled for easy installation.
The benefit of these doors is that they are cheap stable and easy to paint.
Interior doors are usually 1 3 8 thick.
To make it easier to remove the bottom plate under the door cut most of the way through it in the correct places with a circular saw.
I usually do these lamination clamp ups in a vacuum press.
Next use a circular saw to cut out the plywood and sand the wood so the faces and edges are smooth and level.
The unfinished natural wood frame can be installed to either side of the door opening.