Are you looking to replace your front door.
Fitting a door frame external.
Step 1 assemble frame parts lay the frame on a clean dry floor or appropriate workbench where there is enough space to assemble it.
External door frames need to have a waterproof course or builders membrane installed in the rough opening before any frames or doors are installed.
Note that wickes hardwood frames can be used for inward or outward opening doors simply by locating the jambs the correct way round on the sill.
External doors should open inwards.
In addition there will be thresholds and weatherstrips to consider as well as choosing a primer and finish suitable for withstanding the elements.
Measure the distance between the jambs at the head of the liner and cut a piece of timber the same length.
Use a spirit level to get the sill perfectly horizontal.
Insert the assembled frame into the opening.
Fix this piece of timber between the jambs at the bottom of the frame.
This will keep the frame sturdy while you fit it in the opening.