Installing Interior Doors in Old Style Door Frames

Submitted by TheJoker516 t3_10m2t22 in DIY

I'd like to get rid of the 70 style hollow doors with something more modern. I'd like to install them myself, but I can't find any guidance on Youtube. They only show the traditional style door frame/jamb.

Would it be as simple as just taking out the old one and putting in the new one?

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Tolenkanor t1_j619mck wrote

People who have never tried it will assume that a slab door is easier than installing a prehung. Experience shows the opposite is true. A slab (bare door) is cheaper for the initial purchase, but is more difficult to install, and requires additional tools, plus hinges, and way more fussing about.

Search for "slab or prehung door reddit" if you care to see how other redditors have discussed this.

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TheJoker516 OP t1_j61cz0t wrote

Right.. I don't think I'd want to install it with a slab door. I definitely would go for prehung.. Prehungs are more money but not so much more to make it cost prohibitive..

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Traveling_Carpenter t1_j61i8mv wrote

A prehung door comes “prehung” in a frame. You’d have to either pull out the existing frame to put in the prehung door, or - I’ve never seen it done but it could be possible - leave the existing frame and buying a prehung door sized to fit inside that frame, similar to what’s done with a replacement window. You’d lose width and height, and you’d probably end up spending a bunch extra to get a custom-size door (it would probably be about 78 in. tall, and about 2 in. narrower than your existing door). You could also cut down an off-the-shelf prehung door and frame to fit the space, but then you’re getting into territory similar to installing a slab. Like I said, I’ve never seen anyone do this - never seen anyone want to shrink their doors - but there’s not really a reason it can’t be done.

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Becuz_I_Win t1_j60x268 wrote

I'm in the middle of doing this for an interior door.

Option A is to order a "slab" door. Measure the interior dimensions of your frame, and look for a slab door that matches.

Example: 30x80.

Just know, that slab doors usually require finishing.

  • trimming the sides, routing for the hinges, and boring the holes for the door knob. Some doors have a limit to how much you can trim (ex. <1/4")

Option B is to order a "pre-hung" door. This is more involved since it requires you to remove the old casing and jamb, then replace it with your pre-hung door/casing. I haven't done one of these since it's cheaper and easier for me to install a slab door.

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partywithdrugs t1_j624dg7 wrote

Just make sure you measure the depth of your walls correctly. Pre-hung doors are typically made for walls that are built with 2x4 studs and the sticker or packaging will specify this. My house was built in 1973 and the interior walls are built with 2x3’s, so my walls are an inch too thin for a pre-hung door. You can probably guess how I learned that little factoid.

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TheJoker516 OP t1_j62e4mu wrote

why should I measure the depth of the walls if the door that's there now is the same dimension of the one I'm gonna buy?

Edit: I get it.. I'm not going to use the frame.. just the door

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skydiver1958 t1_j64ucy0 wrote

Can you remove doors and fit new ones in existing jambs? Yes but you need to measure and make sure the new ones are the exact same height and width and thickness. You will need slabs as any pre hung there is no guarantee hinge slots and knob holes are in the right spots

Ok so say you have a standard 30x 80 inch door. Well you can use the old door as a template for hinge slots and knob holes. But still might have to do some planing or sanding as you really have no idea what was done to make the old ones fit. But say you get a decent fit. Quite often you need to remove and reset the door stops as they are set to the slight warps of the old one and the new one might not hit right.I've done a lot of doors and sometimes they go smooth and other times you spend time playing around to get a good fit.

So as long as you are replacing a standard size with the same it shouldn't be too hard. Most can be more or less plug and play but there is always at least that "one". GL

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