Interior doors can be pre-hung on different frame or jamb options. Sometimes the jamb availability is based on the market area. Other times it may be desirable to match an existing frame type in an older home. Below are the different jamb options for interior doors.
Flat Jambs
Flat jambs are just that – a flat piece of wood. The standard flat jamb is 11/16″ thick. While the jambs are noted as 4-9/16″ or 6-9/16″, their nominal sizes are 4-5/8″ or 6-5/8″.
In addition to an 11/16″ thick flat jamb, there is the 5/4 flat jamb which is 1-1/16″ thick. While the jambs are noted as 4-9/16″ or 6-9/16″, their nominal sizes are 4-5/8″ or 6-5/8″.
Flat Jamb Stops
Since flat jambs have nothing to stop the door, a piece of wood called a stop is added to the jamb. This prevents the door from pushing through the frame too far.
Single Rabbeted Jambs
A single rabbeted jamb has a built in stop. These frames look very similar to exterior frames. There is an option for a 1-3/8″ or 1-3/4″ rabbet to fit the interior door thickness. While the jambs are noted as 4-9/16″ or 6-9/16″, their nominal sizes are 4-5/8″ or 6-5/8″.
1-3/8″ Single Rabbeted Jamb
1-3/4″ Single Rabbeted Jamb
Double Rabbeted Jambs
Double Rabbeted jambs have two rabbets – one that is 1-3/8″ and one that is 1-3/4″ – so that almost any interior door will work with the jamb. While the jambs are noted as 4-9/16″ or 6-9/16″, their nominal sizes are 4-5/8″ or 6-5/8″.
Split Jambs
Split jambs are a two piece system. The frame is pre-hung together but can be taken apart for easy installation. Very often interior casing is pre-attached so after installation, the unit is complete.
