I'm installing custom door jambs with pine and hanging some solid wood doors.
i secured the jambs in place plumb with 16g finish nails. Are these strong enough or should I hammer in something stronger? If so, what type?

 

How many and how long? ,,,,,,,,,,,,,

 

Currently 8 per jamb plus header 2" long with nail gun

 

That should be fine. It's only the door jamb. The door will stop when it engages the striker plate. Close the door first and let the latch engage in the striker plate. Snug the door jambs against door with just a slight amount of slop to allow for expansion and contraction. Then nail your jambs.

 

2" nails are only long enough if you have no more than a 1/4" shim between the stud and jamb. You want at least 1" of nail penetrating the studs. Any more shim than that and you should have used 2 1/2" nails.

I typically only use 2 1/2" nails when hanging prehung door frames because there are too many cases where 2" is too short.

And you rarely need to nail the head of a door jamb.

 

I was nailing the jambs in plumb and was then going to hang the door and mortise in the hinges after. Should I be hanging the door in the jambs whilst on the floor?

 

I've replaced many doors (prehung and slabs), but always the frame was installed then the door was hung on the frame (pre hung doors the slab is locked into the frame so it's not an issue). Careful location of the hinges is the hard part.

So the question is, are these prehung or new slabs on existing frames?

Send us few pics

 

Depends how good of a job you do at getting them plumb, level and square. I have no idea what kind of carpenter you are. But no, you probably should not hang the doors on jambs while on the floor. You just need to be very sure that your jambs are perfect.

At a minimum I'd suggest you take a slab and just dry fit it into each jamb opening before you put a million nails in them. You should be able to use the slab to check your jambs. 1/8" shims should fit around the perimeter of the slabs. If you set the door into the opening after the jamb is in, you should have 1/8" around it on all 3 sides. If you don't, then its not as plumb level or square as you think it is.

Once you test fit, you may need to adjust. Then when you are satisfied with the reveals, fasten the jamb as well as you like and you will have no worries and no surprises when you go to mortise and hang the doors.

Clearly they are not prehungs.