To help the new basement blend in with the rest of the house we bought a bunch of old interior doors from used building materials place. They are nice solid, heavy doors with that substantial, comforting feel like the houses they came out of. We also bought the old kind of doorknob hardware to go with them.

I am trimming the doorways in the same style as the ones in the original part of the house; wide trim with a thickened pedestal at the bottom and a thin rounded moulding at the top. The dimensions of the original door frames vary throughout the house, so using averages I settled on 4-1/4" wide verticals and 5" lintels for the new frames.

All these frames are made from 1x6 pine lumber. They will all be painted, so I don't really care about the grain or even small knots. I just picked out nice straight boards. The waste from ripping the verticals down to 4-3/4" gets turned into quarter-round moulding on the router, and will be nailed to the bottoms of the baseboards.

This photo shows the doorway to our yet unfinished laundry room. No door yet.
Side note - the laundry room is going to be interesting. The front-loading washer and dryer are raised up on bases to make them easier to load and unload. Each base will contain a big drawer for laundry soap etc. Cabinetry above the machines will feature slide-out shelves for easy access. When I get around to this room I will put up another page showing construction.

Here is the lintel above the doorway, showing the proportions and the bullnose moulding.

The lintel is mounted flush with the door frame, but the side trim is offset about 1/4" to leave a reveal. This provides room for the hinges to stick out, and for the door latch not to hit the trim when the door closes. It also just looks good. A practical reason for the little bullnose moulding at the top is to tidy up the joint between the vertical trim and the lintel. The vertical trim does not always lie flat against the wall, especially in old construction.

A door jamb is a little wider than the thickness of the wall. The edge of the jamb where the trim gets nailed on is usually slightly bevelled back toward the wall, so that the edges of the trim can lay flat against the both the jamb and the wall. See my exaggerated drawing at right. The vertical pieces of trim usually don't lie flat on the wall, but lie at a slight angle. So the little bullnose trim at the top serves the practical purpose of hiding the discrepancy where the verticals would otherwise butt against the lintel. It's not just a fancy bit of frill.

I'm sure this bullnose moulding can be bought, but I made my own, using my thickness planer to reduce a 3/4" board down to 3/8" and then ripping it into 1-1/8" strips (3/8" wider than the thickness of the lintel). Then I used a router with a 3/16" rounding over bit to round off the front edges. After cutting a piece an inch longer than the lintel, I round off the ends using a sander.

Our baseboards are 7-1/4" wide (standard 1x8s), so the pedestals are 8" tall by 5-1/4" wide. Just a bit taller and wider than the boards that butt against them. I'm making all the pedestals from pieces of ordinary 2x6 (selected for no defects), milled down to 1" on my thickness planer. You can buy 1" thick lumber, it's just more expensive than standard. The pedestal is flush with the inside of the door jamb (no reveal) and the vertical is about centered over it.