Home Improvement Bleg
Posted by
tgirsch
So I’ve got a new pre-hung door that I need to install in a newly-constructed section of wall. Here’s the problem: The jamb of the door is 4″. A 2×4 is actually 3.5″ thick. Add a piece of 1/2″ drywall on either side, and you’ve got an opening of 4.5″. So WTF am I supposed to do about the extra half inch?
I checked all the doors at Lowe’s, and they’ve all got 4″ jambs. So how’s this supposed to work?
Well, the trim on my doors hang over the wall a bit. Barring that, they make these things called ’saws’.
Comment 12/11/2007
Shim it, unless I’m not understanding something.
Comment 12/11/2007
most jambs are 4 9/16 (6 9/16 for 2X6 walls). If you truly have 4″ jambs, I would look into returning the doors. Short of that, you should install door so jamb is 1/32 proud of the drywall on one side and then attach an extension jamb on other side to be 1/32 proud (probably 9/16). I hope you have a table saw…
Comment 12/12/2007
Ted:
I stained the door before hanging it, so no returns possible. But all of the doors I could find had 4″ jambs. Really weird.
Uncle:
If the door jamb is already too small, I don’t see how sawing more off will accomplish anything.
Kevin:
You must not be understanding me. What we’re talking about is the front-to-back part of the door jamb; it needs to be flush with the drywall on both sides so that the casing trim will fit flush. Maybe this diagram will help.
When you put in a prehung door, you take the casing off one side, and set it into the wall, so that the casing on the other side is flush with the wall. If everything works correctly, you then nail it into place and reattach the casing on the other side, and it should all be flush. But in my case, on the other side, the jamb falls 1/2″ short, so I’d need to trim out with 1/2″ extra all the way around, as Ted suggests.
Comment 12/12/2007
Yeah, trim it out with 1/2″ strip on the other side. If that’s the only problem you run into when doing a remodel, consider yourself lucky. The guy who built my last house seemed to have a T Square that wasn’t actually 90 degrees.
Comment 12/12/2007
Most pre-hung doors come with a split jamb, not a solid jamb, and are adjustable for width. I haven’t bought a door with a solid jamb in years. You need to check to ensure that you don’t have a split jamb as your diagram illustrates. They are adjustable out to better than 4½ inches.
Comment 12/12/2007
ding ding we have a winner. It has to be a split jamb. No doubt. My company only does high end work so we never use split jambs, but if your door has casing already attached, it HAS to be a split jamb.
Comment 12/12/2007
*raises hand*
So how do I adjust the split jamb? I don’t see any obvious way to adjust it.
Comment 12/13/2007
you probably have to remove a couple screws or nails and the two sides come completely apart
Comment 12/13/2007
yanked from a DIY site……
Remove all packaging materials, blocks and nails from your door assembly, and separate the jambs.
Place the closed door in the rough opening and center it. Use a level on the hinge side of the casing to align it vertically. Tap shims into place between the door jamb and the rough framing to make the jamb plumb.
To hold the door in place, nail through both the jamb and shims into the wall stud near the top hinge using an 8d finish nail. Any nails that you drive through the jambs should also go through shims behind the jamb. This is necessary to prevent distortion of the jamb in the nailed area which could cause the jamb to bow outward at the nails.
Do the same for the other hinges.
Check the door’s alignment with a level again before continuing around the door jamb installing shims and nails in the same manner. The space between the jamb and door should be the same for the entire length of the unit.
With a saw, trim any shims that protrude from between the jambs and framing to allow the second jamb to be installed. Be careful to avoid damaging the jamb or wall. Slide the second jamb and casing unit in place against the first.
Nail through the center of the stop and jamb to secure the second jamb. align the nails with the ones you installed in the earlier steps to ensure that the nails will go through the shims as well.
Nail the casings to the wall at 16″ intervals with 4d nails. Use a nail set to recess the nail heads.
Install the doorknob. The holes for the knob and latch assemblies should already be cut for you. For more about this subject, see Installing Locks and Deadbolts.
Comment 12/13/2007
See, it’s the “separate the jambs” part where I get stuck. When I hung the door originally, I had instructions that didn’t include that step, so the door is already up. I’ll probably take it back down and start over, most likely with a new door.
Comment 12/13/2007
You dont need a new door, you can buy a jamb kit if you have destroyed your jamb…
Comment 12/13/2007
I don’t think the jamb is destroyed; I’ll just have to take the door down and see what I’ve got.
Comment 12/13/2007
or leave door in place and remove walls
Comment 12/13/2007
That is what I was thinking.
Comment 12/20/2007