Slab door or prehung?

Didn't want to hijack the other thread.  I have 6 interior doors that are junk and since the cars are running and the boats still float I have time to go after this.  So the slab doors are cheaper but I will have to mortise in the hinges and drill the knob holes.  It doesn't look that bad but many here have done it.  I know there are drill guides for the knob, but do I chisel for the hinges or borrow a router?  Can I use the old door as the template?  I hate door work, every time you use it a mistake stares you in the face.

I replaced doors in an older house with brand new slabs. The router jig and a small trim router for recessing hinges makes the job really easy. Use the old door to mark the locations for the hinges on the new door.

I would rather stab myself with a fork in the nuts than hang doors. 

I have hung hundreds of slab doors, and I am VERY good at it.  I still choose to replace the entire frame whenever I can.  It's a lot easier.  I can hang about 10 doors an hour that are pre-hung (new construction).  Mortising a door properly will usually take nearly half a day for me.

If you've never done it, I can almost guarantee you will overcut something on the mortises which will annoy you for a long time.

Are you sure the slabs are cheaper? You have to add the jambs, stops, casing, and hinges.

I've changed out a bunch of nasty hollow interior doors for solid slab ones in my last couple of houses. I use the old door as a template and use a chisel to mortise the hinges etc. It's not rocket science, you just have to pay attention. I usually don't replace anything else other than maybe hinges and the lockset. It's a big improvement. Since I'm my own client, taking a couple of hours to get the fit right is not a problem.

Haven't done new construction, so I can't comment there. Also have not stabbed myself with a fork in the nuts, so cannot offer a comparison.

I think it depends on the extent of the surrounding renovation.  Are you replacing everything? A pre-hung will be easier, but if in an existing wall, you'll have to re-trim the door on both sides.  But if you're re-trimming the rooms, then this doesn't matter as much.  This also assumes the sizes for all of the doors are standard. 

What is exactly "junk" about the existing doors? My ex's house had a lot of old doors she pulled off and refinished (mainly, stripping off decades of paint and then reapplying a fresh layer), since it is an old 1800's house and all of the doors were of non-standard sizes and re-framing the openings was not an easy option due to old-house, atypical construction. 

In reply to Ian F (Forum Supporter) :

That's a good point on the sizes. Prehung doors are very limited in size availability, and frequently don't fit openings in very old houses.

They are also almost always hollow core, and not the same quality or heft as older doors (or solid core new slabs, which generally don't come prehung).

If you have mortise locks in your old doors they may be worth the effort to save. 

95% of the doors we install are slabs. The difference being I order them pre-prepped for the existing hinge locations and locksets. From there it's a 30-45 minute job to swap the door out. Changing a frame adds 3-4 hours to the job. 

You can probably do that for residential doors but it would also add a fair amount to the cost of the door. 

With a couple of jigs, one for the hinges and one for the lockset, prepping the doors isn't that difficult as long as all of the sizes are standard and you are careful with your measuring. You can probably do 6 doors in a day once you get set up to do it, assuming they are all identical. The first one will take you an hour or two, the last one, less than half that time. 

The old doors are luan and have a few holes.  The jambs and hinges are fine.  Same with the door fram molding.  I cannot see any reason to rip everything out, risk damaging fresh paint on the molding and doors to fix this.

I can practice on the lock side of the doors to mortise hinges in, is this a chisel or router job?

I use a chisel. 

Luan doors have no redeeming qualities whatsoever. 
 

If you are doing 6 of them, I'd use both a router and a sharp chisel. The router is the easiest way to make a nice flat surface for the hinge to seat against. The chisel is the best tool for cleaning out the corners and fine tuning any small issues.