Doors and Windows - Interior door installation question

Hello,

I am trying to update all of the interior doors in my house. I want hang prehung doors because the old doors sometime stuck and I didn't have a good template to work from. I removed the first door, the jamb and am left with a rough opening that is 80.5" tall and 32" wide and 4" deep. The pre-hung door that I purchased does not fit because the rough opening is not tall enough and the depth of the new jamb is 4.5". I don't want to spend too much on these doors as we are planning on selling in the next 6-9 months.
Can anyone please tell me if there are pre-hung doors available at that height or am I going to have to reframe the opening? Also, the depth of the new jamb is off and I don't know how I would get the trim to lay flat against the drywall with the extra .25" on each side hanging over. Any help would be greatly appreciated. Thanks so much!

Welcome to the forums! What type wall covering do you have on each side of the studs? Normally, with a 3 1/2" stud, and 1/2" sheetrock on each side would equal 4 1/2". You may be able to fit your doors if you look at the bottom. There should be maybe 1/2" excess framing that could be trimmed off enabling you to fit it into the opening. Of course it will lower your door, so any floor covering will need to be taken into account.

As previously mentioned, there should be room to spare on the bottom of the door frame as well as the door if necessary.

Assuming that it is a hollow core door of some sort, between and under the door skins, and located at the very bottom of the door, there is very likely an 1 1/2" solid wood support (faming) member which should give you more than a sufficient amount to cut down the door,and thereby reduce the height of the door without impacting its structural integrety and fit into your opening. Reframing the opening will innvolve a lot of work. That framing structure should continue around the parimeter of the entire door to add support and to allow for modifications.

If the doors jamb is 4 1/2" deep (as you indicated) it is a standard size and should fit assuming the wall thickness is standard 3 1/2 stud and 1 drywall.

Ther is no magic to cutting down a door, you just need to measure correctly and cut a straight line. ust be sure to use a straight edge as a guide and your cut will be perfect.

Thanks for your responses. I don't think I did a very good job explaining. The existing rough opening of the door is 4". There is a 2.5" stud and a .5 in slat of wood on either side. The drwyall runs up to this slat on each side. The house is 50+ years old and I think they tried to build as cheaply as possible. The door jamb that I bought to install is 4.5". I am trying to locate a pre-hung door that will allow me to fit this smaller opening. Will a split jamb be of any assistance or is that only if the opening is too large?

I have pictures, but I don't know how to post. I would be happy to send them to anyone who thinks they could help out. Thanks!

If you have a tablesaw you can rip the jambs to the width you need. Cut the door and jamb height to fit your opening with a circular saw. Use a fence/guide to make sure your cuts are straight and square. A pain but not a hard job.

IMO split jambs are junk. At least the ones sold at the big box stores. I don't think they would help much in your case. You would still have to cut the jamb width. While they expand, I don't think they will go much narrower than 4.5".

Thanks for the response. I do have a table saw (my husband does) what do you mean rip the jambs? Do you mean cut off a quarter of an inch from the jam all the way around on each side? I will not be doing the actual work because I am not that handy, my husband will. But, I do know how to ask questions much better and do the research to learn how to do something.
The big box stores have not been very helpful!
Thanks!

Ripping the jambs means cutting their width to match the thickness of your wall. Remove the door and disassemble the jamb. They are usually just held together by staples or small brads. It's best done on a table saw.

The lack of knowledgeable help from big boxes is frequently mentioned here.

I'm trying to figure out my interior doors so I'm reading up. Did you consider using the existing frame and just putting a new door in place? Not sure if that would be easier or not.