Trimming out prehung door

[Bob Cooper]

I know this is not so much of a woodworking question but we all do this type of stuff too so I’d like to get a couple opinions.

I’ve got a couple pre hung doors that I’m trimming out at home and the frame sticks out about 1/4”-3/8” past the drywall. So I’d like to plane that down so the 1x4 trim sits flush against the drywall.

What the best approach?

Handplane? Seems like a lot of material to remove
Flush trim route bit? Worry that drywall won’t be a great pattern to follow.
Power plane?
Put a spacer on the other side of the trim?

Really curious how trim carpenters that knock this stuff out quickly solve this. And don’t say “they don’t let this happen” ;)

[Kevin Jenness]

One way is to set up the jamb plumb, mark it, pull it back out and cut to the lines with a track saw. I have trimmed jambs in place with a power plane and with a router set up with a subbase for flush trimming where the base rides on the drywall, finishing with a block plane. You can also build up the casing thickness with spacers where needed.

One way to ease the trimming process is to dado the back of the casings so they bear on the jamb and wall surface only on the edges and span over some unevenness in between.

[Richard Coers]

If the gap is close to the same all around, and you are truly using 1x4 stock for casing, I'd cut a rabbet on all the casing pieces.

[Andrew Seemann]

If the door isn't secured yet, you could center it in the opening so the 1/4" ends up split on both sides at 1/8". You might be able to hide that with just the casing.

[Bob Cooper]

The jamb is in place and I did try and center it as best I could. The casing/trim on the other side is finished so I really cannot remove them, scribe,…

Also the gap varies. Good point though about the rabbet…I could do that to get rid of some of the difference

[David Stone (CT)]

I've run into this situation in renovating my old house, where walls, windows and doors are never plumb and usually out of whack in other ways also. Adding extensions to the outer edge of the casing (or, as suggested above, rabbeting the inner) and trimming down the jambs with a router on an offset base followed by a clean-up pass from a plane will both work. The first method is going result in trim that may be noticeably thicker or thinner in places than the rest of the room, so you need to decide if that will be objectionable.

In the door shown, the wall was twisted and wildly out of plumb. I elected to split the difference, which required adding tapered jamb extensions at the top of the opening and building out the lower parts of the casing with tapered pieces glued on to the back edges. Having a woodworking shop is a real plus in this situation; it'd466798 be tough to accomplish with site tools.

[Mark Bolton]

Scribe, pull them out, cut them and reinstall or make a quick overhanging shoe for your router so you can run a straight bit in your router and the base of the router rides back on the drywall and you can flush the jambs all but the very bottom (make your shoe with a tapered front so you can trim to within the distance of the floor of the router base).

The problem with trimming with a shoe is if your drywall is coming and go-ing more than your casing will allow you'll still have gaps where you wont be able to draw the trim in tight.

The best solution is to scribe the jambs, remove them, cut them a shad proud but straight averaging the wall variation then re-install them and skim the wall out flat as it should have been. Tough to deal with in older homes or drywall where someone landed a nasty seam(s) somewhere in the opening.

[Rich Engelhardt]

The Dremel Ultra will make flush cuts.
It might be worth looking at.

I dislike anything Dremel - but - they seem to be the only ones that have a small saw like that which can make a flush cut.