Old homes may have thicker walls than what are standard today. To properly fit an interior door in your home, the door jamb must match the thickness of the finished wall or be slightly deeper than the wall. If the wall is thicker than the jamb depth, the door trim (called casing) will not fit properly over the jambs and wall surfaces. Dimensions A standard interior wall consists of a two-by-four frame with one layer of 1/2-inch-thick drywall on each side, for a total thickness of approximately 4 1/2 inches. The depth of a standard door jamb is 4 5/8 inches, which provides an extra 1/8 inch to account for slightly thicker walls due to stud size variation. Variations While most modern homes have standard wall thicknesses, older homes often have thicker walls, as well as variation in thickness from wall to wall. For these cases, you can try a special split-jamb interior door, which has a slightly adjustable depth. Another option is to create door jamb extensions: hold one side of the door jamb flush with the wall and measure the distance needed to make the jamb flush with the opposite side.
Use a table saw to rip strips of wood to the width needed, and attach the strips to the edges of the jamb. References The Detering Company: Door GuideThis Old House: Extending Door Jambs Photo Credits Jupiterimages/Comstock/Getty Images Suggest a Correction1-Panel Knotty Pine Single Prehung Interior Door with Bronze Hinges Sign up or log in to customize your list. Here's how it works: Anybody can ask a question The best answers are voted up and rise to the top Normally a 2x4 wall has a finished thickness of 4.5" (2x4 + 2x 1/2" drywall) I have 1/2" soundboard under one side of the drywall so my finished thickness is 5" I know that I can custom-order pre-hung doors with this jamb size, but is there way to cleanly install a standard 4.5" jamb? Should I install flush to one side, leaving the half inch and add a moulding to cover it? Should I split the difference to 1/4-inch on both sides? doors framing finishing door-frame One approach is an oversized pre-cased, split-jamb door.
These have casings (room side moldings) pre installed to the jamb and are attached separately from each side. The joint in the middle is hidden by the stop (the molding that the door actually rests against when closed). This is a home center site describing the process. These doors probably would have to be special ordered and cost more than standard prehung doors. An alternative is to create your own jambs using standard clear boards. This does require some skill with either a chisel or router, but is not beyond the skill level of a fair DIY carpenter. You could also install a standard pre-hung door with the jamb on the hinge side flush to the outer edge of that wall. This will leave the other edge of the jamb about 1/2 inch recessed, the thickness of the soundboard. Just putting a narrow piece of board the same thickness as the jamb would work (there is no structural issue). However, butt aligning boards generally does not look good - the edges shift slightly and it always looks like an unintentional (or unprofessional) joint.
The standard way to solve that is to create a reveal. This is a small step in level between two adjoining lengths of wood. You could put in a simple square edged molding (or thin strip of board) that is set back from the inner edge of the jamb opening about 1/8 to 3/16. If the soundboard is tight up against the jamb (it really shouldn't be, but sometimes is) use a board/molding slightly thinner than the jamb. Other wise, just slid it back a bit. Then when you measure for the casing. create a second small reveal set back from this filler strip. Another, simpler, but less elegant approach, is to use a backband or cap type molding. The one illustrated is a bit deep, but you can probably find one smaller and simpler. Putting the shorter edge on the outside edge of the short jamb with the thin edge overlapping onto the inside edge of the jamb. Then nail the casing agasint the cap/backband. Becasue the door opens on the hinge side, this inset molding should not interfere with functionality.
I've done this in a similar situation. Rip some 1/2 by 1/2 strips of whatever you have. Glue them to the inner edge of the casing you are going to use. Use a jointer or a plane to make the two pieces flush. You would be making a custom version of the cap moulding 'bib' shows above. When you install the door, you can either center it in the wall and use the modified casing on both sides, or hang the door flush on one side and just use the modified casing on the other. Like Bib says, a split jamb door will do it. I bought one a few weeks ago and it was split jamb. I think most are that way now. It didn't cost extra. So it simply slides to the thickness you need. It even had the casing already around it too. So the first thing you do is split it into two halves, mount one half by attaching to the casing, then adding shims inside the jamb, then slide the other half into place. Sign up or log in Sign up using Google Sign up using Email and Password Post as a guest
By posting your answer, you agree to the privacy policy and terms of service. Not the answer you're looking for? Browse other questions tagged doors framing finishing door-frame or ask your own question. Before you choose your new pre-hung door the size of the opening is important to know. Getting the right size door for the opening helps to make your installation smooth and will eliminate some very big problems. Measure the opening to your door frame. Be sure to allow for about a 1 1/2 inch larger opening than the standard door sizes. Typically a pre-hung door is measured in 30 inch and 36 inch sizes with additional sizes available in non-standard widths. The doors are also a standard 80 inches tall. Presuming the door is a 36 inch wide door, the dimensions of your opening should be 37 1/2 inch wide by 81 1/2 inch tall. Reasons for Door Opening Size When a pre-hung door is being installed into an opening there have to be considerations for leveling the door, and ensuring that it has a obstruction free swing.