Building a door jamb - 36" exterior

[tyb525]

I am putting in a 36" exterior door, it is used so it does not have a jamb. I don't want to fork out $40+ for a pre-made one at Lowe's.

I need to know what dimensions I need to make it, i.e. is there is a standard jamb size, or do I measure the door and then add for a small gap around the door?

Thanks

[jdtuttle]

For the width add 1/2" for a 1/4" reveal on each side. The height will be determined the same way except add extra for the threshold. hope this helps.
jim

[tyb525]

Ok thanks, I just wasn't sure how much reveal was normal.

[Planman1954]

The width of the door jamb is determined by the wall finish used on each side of the door. Say, for instance that you have 1/2 " Sheetrock on one side of the wall, and 3/4" siding on the outside of the wall. If you have a 3 1/2" thick stud wall (which is standard) you would add 3 1/2" plus 1/2" plus 3/4", or 4 3/4" thickness. This would be the width of your new jamb. The sheetrock and 3/4" wall material should butt up to the new jamb. This allows trim to run flush along the jamb. Good luck!

[trim4u2nv]

Be sure to substitute 2 of the short hinge screws for extra long screws on the top hinge.  These shoud be put through the hinge, jamb, and jack stud especially on the top hinge to prevent the door from sagging.

[tyb525]

Yes, I knew that from previous building experience. I have just never had to make a jamb, we've always used pre-hung.

But I'm completely remodeling a 100+ year old kitchen, and partially remodeling/updating the rest of the house for a family member. So anything I can do to save money is a good thing, as long as it is done right.

Gotta love trying to adapt to balloon framing methods, where there is no real foundation, just brick pillars every 4-6 feet : Nothing is level or square, and the walls can have dips/waves as much as 1"+

[trim4u2nv]

I did a 1910 building in 5/4 white oak jambs that was all balloon framed.  The biggest challenge was compromising on keeping the door in the same plane with the wall versus leveling prehungs with a plumb bob.  The lady that ran this office thought the place was haunted because quite a few doors always shut all by themselves.

[jdtuttle]

I have done renovation work on numerous old houses. Your better off without the level in most instances. Look for straight lines & compromise. The only exception is the Kitchen & Bath. Use your level there. Good luck  ;D
jim

[thecfarm]

I use to work for the state on low income homes. We did not use a level on some things. Just stand back and eye ball it. If we would of used a level,the door or window would look pretty bad.

[Handy Andy]

  You need to look at a boughten door jamb before you start this. And see if you can get the sill they use that sits on top of the floor.  Course your old one was probably notched into the floor. The wrapped weatherstrip they use now is great, it slips into a slot cut into the corner of the notch you make in your doorjamb.  Start with a 2" board, make the cuts for the offset on your tablesaw, and the long side run your blade about 1/2" deep.  And your shallow cut will have to be wider to allow for the weatherstrip.  Think it was an extra 1/4. So, you have a notch 1/2 x 2".  And your 2" cut needs to be about 2 &1/2".  Make your top notches 1/2" to match the offset for the door, and also the bottom.  Seems that sills were cut at 7 degrees if you have to make one. make the same length as the top, except you have to leave the "ears" stick out so the trim sits on top of them.  I'd make the height of the jamb about 3/4" taller than the height of the door,  and the width of opening for door 1/4" wider. That is if you are using a 1 3/4" exterior door. Use a thin kerf blade so your slot isn't too wide for the weatherstrip.

[tyb525]

I do have the old sill actually. The bottom half of the frame that came with this used door was torn up beyond repair, but the sill is fine.

All the exterior doors in this house are 30", too narrow to get much furniture in, which is why I'm replacing one of them with a 36".

Thanks for the in-depth tips, Handy Andy,

[Clam77]

Just as a thought.... you MAY want to check your local building codes and maybe ask an inspector... Alot of places mandate that when you do a remodel you have to make the doors wheelchair friendly - especially if the building is going to be open to the public.  This includes both innner and outer doors.

[Larry]

Don't forget to leave space for door clearance when you mortise the hinges.  Normal is 1/8" for new construction.  For old work sometimes it is better to trust your eye and make it whatever looks good and works.  Doors that just open and close can be a major accomplishment.




When cutting jams I leave about 1/16" clearance (2 degrees) on the edges.  This allows the casing to flush up nice and tight.



Good luck and don't pull too many hairs out.

[Handy Andy]

  Years ago, before prehungs, used to trim houses.  When making exterior frames with 1 3/4" doors, allowed 1/4".  For interior doors 1 3/8", allowed between 1/8 and 3/16".  That is if you don't want to plane the door to fit the jamb. Did that a lot when the jambs were made 36 1/8".  Used one of those old porta planes.  Still have it.  Haven't used it in years. Really like that wrapped foam weatherstrip.  Much tighter than anything that used to be available.