Framing new interior door

Since you’re filling in an existing opening, you don’t have to worry about supporting the existing structure. The framing already in the walls takes care of that. You only have to put in enough framing to support the door.

You can remove the existing drywall if you want, but it’s not necessary (see above about structural integrity). On the other hand, you’ll feel better if you remove it, and that’s worth a lot.

You didn’t provide a photo, so I’ll assume the existing drywall installation is typical. Every corner should have at least three inches of support behind it, either the edges of two studs or the face of one; so you should have plenty of room to put more screws into the existing wallboard.

Yea, I wish you had supplied a photo too. I would like to see this odd shaped opening before making any judgment on what you may be attempting to do. Some odd openings are not what they seem to be.

-- Methods are many,Principles are few.Methods change often,Principles never do.

Ok, here is a photo of the opening. Please ignore the extra crap inside the room.

Just off the left edge of the photo is the front door. This is one of 2 entrances to this formal living room. I am hoping to close it in with doors to provide it with some privacy and noise control so it can be used as a music room, a guest bedroom, etc. I would like the doorway at this entrance to be as wide as possible. Unfortunately the current opening is 50”, so I don’t see any way to get a 48” double french door centered in this opening.

As you can see, the opening is an inverted L. You both are suggesting I can simply nail the top plate through the ceiling drywall. I suppose I should at least knock the texture off so the top plate lays flat against the drywall. A friend suggested using 3” decking screws to attach that.

The other issues are the king and jack studs for the rough opening. For the moment don’t worry about the tile; I installed the tile and I’m confident I can either cut it in place or remove / replace the affected pieces.

On the left side of the opening the options I can see 2 options if I want the opening to stay as wide as possible. Regardless, I expect to remove the narrow strip of drywall that faces into the opening. Option “A” is using the existing framing as the king stud and add a jack stud up against the existing framing. Option “B” is to notch the existing framing and fit the header into the notch.

On the right side of the opening I expect I would have a typical king stud / jack stud arrangement, positioned so the rough opening is centered. If I use option “B” above, the king stud will, I think, need to go next to the existing framing. In that case I’m thinking of leaving the drywall on the short wall to overlap the existing framing 1/2” so it can stay nailed to that. Then I would cut a 1/2 rabbit in the king stud to fit over the drywall.

A few other questions:

What should I use for the header? I thought 2×10s would be more than safe. The final rough opening will be maybe 48”.

When do I need to install sole plates? For example, in option “A” where I’m just nailing a jack stud up against existing framing on the left side does it really need a 1-1/2” long sole plate between it and the slab? On the right side the new sole plate would be either 3” long or 4-1/2” long. I’m pretty much resigned to putting in that one although it seems a bit silly if the king and jack studs are right up against existing framing.

Thanks for your help!

BTW, regarding doors, I’m expecting to need to build them custom. I could find no interior doors between 36” and 48”, although I did find some expensive 42” exterior doors. I’m expecting to end up with 22” or 23” double doors.

How about this:
The rough opening will be 51” if you remove the wallboard on both sides. Your 48” door should fit in that.

Doors in non-load-bearing walls don’t need a header, so frame the portion over the landing separately, lining up the new edge with the old framing, then frame the portion over the door with a 2×4 on the flat as the top of the rough opening. (Even if that wall is load-bearing, the existing beam at the top is taking the load.)

Attach your pre-hung door to the existing framing. If you have to, you can use 3/4” material to shim out the opening.

Your only remaining problem is cutting down casing to fit around the narrow edges.

On interior pre-hung doorways, door size +2”+6” framing, case out door trim std. 2 1/2”. In your case 45” door+2” +3” (you already have king stud and trimmer on one side).case out door 2 1/2” trim.Any thing larger than a 45” door and you will be ripping trim.when done your base on side walls will slip behind door casing.example if you set a 48”hall door the rough frame for the hall will be 56”.All your trim work will then fit. you only have 53” of hall.

-- Michael

Michael – Yes, I was expecting to end up between 44” and 46”.

SteveB – The book I checked said no header as long as the space between the top of the door and the ceiling is no more than 24”. If I match the height of the other doorways I’ll have about 26”. It didn’t say what to do in that case.

I’m thinking of using a joist hangar (the style with the flange on the inside of the hanger) to attach the header to the existing framing on the left side rather than notching the existing framing.