Can someone tell me how to set the jam stock in a doorway

[wotan]

I recently framed in an extra closet in my bedroom with the help of my buddy. I finished all the drywall  and now I need to trim it out. When we framed up the closet, I found out that my wood floor sagged about an inch and a half, so I have a gap on the right side (facing) and I don't know if I should trim the left side even, or just scab in a small piece at the bottom.  Also I don't  know where to start with leveling the Jam stock and what size nails should I use to attach it with.

I tried to start it once by using my finish nailer and working up one side and then using shims along the top, but when I got to the right side I ran out of space to move the stock and couldn't get it level.
what am i doing wrong?

 

[Notorious T.O.D.]

Is it a single door or multiple doors?

Todd

 

[nickao]

There are a few door specialists here that can help, I have made more doors than installed.

 

[Dave Ronyak]

Wow, that is a lot of sag!  Whenever I see Tom Silva encounter anything near that on This Old House, he is usually headed for the basement to inspect the foundation.  Then he often sets up some jacks and beams and slowly and gradually lifts the house structure back toward level.  I did this once on my former house to correct doors that would no longer latch, but the amount of sag was not nearly half as much as you described.  The drywall did not crack.

Hopefully, others who have more experience in dealing with this issue will jump in with an answer you can use.

Dave R.

 

[wotan]

It is a single door, and it is on the second floor of my house. Correction, it is about 1 1/4" difference in length. My house was built in 1912 and uses 3 massive metal i-beams for support. i have plaster and lath walls with no cracks. The floors just sag a bit.

 

[Notorious T.O.D.]

Well, being a single door makes it a lot easier.

I'll assume that the lock side is 1 1/4" lower than the hinge side. So the lock side jamb will need to be 1 1/4" longer than the  that the hinge side jamb is from the bottom of the jamb to the bottom of the dado for the top jamb.  This is assuming a standard 80" tall door.  So, you will trim the door so it is 1 1/4" shorter on the hinge side of the door at the floor.

I don't know if you are making your own jambs or using purchased stock.  I usually make my own from 3/4" stock and I bevel each edge about 3 degrees and cut 3 or 4  dados 1/2" wide and 1/8" deep into the back of the jamb stock.  I also cut 3/4" wide by 1/4" deep dados in the face of the jambs for the top jamb piece to go into.  So, if your door is say 36" wide the top jamb piece would be cut to 36" plus 1/2" for the two dados plus the width of 2 nickels which is about 1/8"+ or 36 5/8"+ total. 

I also bevel the edge of the door on the lock/doorknob side about 2-3 degrees so you have clearance when closing and opening the door.  So, the door is widest on the side you see and a tad narrower on the side inside the closet due to the bevel.

I usually put the top jamb into the side jambs and drive a pair of screws from the backside of the side jambs into the ends of the top jamb which is in the dado of the side jamb.  I keep these screws maybe 3/4 " form the jamb edges so they can be loosened slightly if needed for adjusting the width of the top jamb.

I then start with the hinge jamb and and get it plumb vertically and even with the front and inside walls.  Now you see why we want the tapers on the jambs so that the door trim can land on the taper and leave a nice little reveal and lie flat on the wall, the other spot where the trim will be nailed.

You want to put shims behind the hinges on the hinge jamb and keep the shims so that you have room to shim the lock side jamb too.  I often use long screws to put up the side jambs drilling the holes where they will be hidden by the door stop molding when it is installed at the end of the door hanging. Using a few screws here makes it much easier to adjust things than if you use a nail gun and nails to put it all in place.  Once the hinge side jamb is in place and secured with a few screws and all shimmed nice and plumb you can level the top jamb with a 90 degree square and/or a 2 ft level.  Once that is level then you can shim and plumb the lock side jamb.  And now you are ready to hang the door assuming you have mortised in the hinges already.  If the door fit is tight side to side you can loosen the two screws on one end of the top jamb and slip a penny into each side of the dado and retighten the screws.  This will usually give enough clearance and the tiny gap at the dado will be covered by the door trim.  What I am looking for is a nice even nickel width gap on both sides of the door and with the top of the door and the top jamb... So, if you mortise the jamb for the hinges first, you then need to move the hinge mortices location on the door edge by a nickels width to leave the clearance at the top of the door. Of course the easy way to make this is to tape a nickel on the top of the door and set it in the jamb to transfer the jamb hinge locations.

Last the door stop is added after the lock/knobset is installed and latching the door properly. Simply close the door and put the door stop right up against the door or if you want you can use a dime as a spacer which is a good idea if your door and trim are not yet finished  so you leave a little room for the finish films.  Then it is just a matter of putting the trim around the door.  And keep in mind that you want the top of the doors in the room to be at the same height all around the room.  This can result in you needing jambs that are either shorter or longer than normal.

Hope this helps and is not too confusing.  It is one of those things that is much easier to show someone than to describe in words.  If you have questions just ask.

Best,
Todd

 

[Eli]

I do it much the same way Todd described, excellent description.

Todd left very little unsaid:

I'd add that if the two side walls are very out of plumb you can cross strings on the front of the jambed opening and get them to touch in the middle, ensuring both legs sit plumb relative to each other/ in the same plane. This will prevent your door from touching door stop in one corner and having space in the other. Also make sure if you fabricate your jamb stock that it is wide enough to be flush or even better stick out a shave from the surface of the wall (the face of the wall). This will help the architrave sit flat when you trim out the door, which will make your miters a bit easier/better.

I nail the jamb and stops in with a finish nailer, but I throw out the hinge screws that come with the hinges and use longer ones, to go through the jamb and into the rough framing if I can. Make sure all the hinges (and the strike on the other side) have solid shimming behind them, or the screws will suck the jamb all out when you sink them.

Don't be surprised if you buy prefab jamb stock to see that the dados might be in the (short) top piece to accept the legs and not in the legs themselves. They are delivered like that here often.

Be careful about having the hinge side bottom of the door being shorter than strike side in that the longer strike side may hit the floor when you open the door fully. Depends on what the floor is really like.