What is the difference between a prehung door and a slab door?


             We get asked all the time, what is a prehung door and is it better than a door slab? First let’s talk about what a prehung door is. There are many parts and components that make up a door unit. The most obvious part  is the door slab itself which is what you open and close.  Another component are the hinges that allow the door slab to swing. You also have the door jamb which is the frame that surrounds the door slab in the closed position and houses the weatherstripping that blocks out exterior elements from entering the home. The threshold/sill is the bottom portion of the frame that rests on the floor and what you walk over when entering through the door. If you have made it this far, you are probably still wondering what is a prehung door?

                A prehung door is a door slab that is “pre-hung” in a frame from the manufacturing company. Basically all the above components pre assembled together to create a door system that is ready to be installed into your home. There are different types of prehung doors including single prehungs, double prehungs and prehung doors with sidelites. A door slab is just the door itself. Most of the time the door slab will come with no door knob holes and no hinge mortises (cutouts). Also typically full sizes and are required to be cut down on the width and height before installation. Installing a slab door only, means that you will need to hang the door only on-site in an existing door frame. Doing this limits the ability to get a great seal and proper operation because of using existing conditions that may not be square, level and plumb. Prehung doors are the best solution when replacing the door in your home. This is due to the fact the door can be installed square, level and plumb in an existing rough opening to allow the best fit, operation and seal. So make sure to consider this on your next door replacement project.

               While a prehung door is going to be the majority of your materials for a door replacement project, there are other materials and parts that may be needed for completing the project. Typically door knobs and locks are not part of a prehung door unit. These can be purchased separately and installed on the door once the prehung door is installed. Interior casing is another component that is not included in a prehung door. Often times interior casings can be removed and preserved to reinstalled once the prehung door is installed. Other times new casing may be required to complete the project. And lastly sill support materials are sometimes needed to finish off an installation and items for this are also not included in a prehung unit. 

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