It used to be, not so long ago, that just about every carpenter hung doors from scratch. But as we rushed to build faster and more efficiently in the post-WWII boom years, specialty shops began making prehung door assemblies that required less skill and less labor to install.

These days, carpenters routinely install prehung doors in both new construction and remodels. But prehung doors are not very forgiving, so having a systematic approach to installation is crucial to being efficient and leaving behind a solid, problem-free product.

We start by unpacking and inspecting every prehung door we take delivery of. In order to have a successful installation, the door slab must fit properly within the jambs with even reveals and accurately mortised hinges. The door itself must also be square. If I see any issues, I send the door back—an improperly fit prehung door can be very difficult to install with any degree of success.

When I first started out, I’d just grab a prehung assembly and try to wrestle it into position. But I’m much more methodical these days. I’ve realized that if the door has been prehung correctly, most of my work should be focused on the rough opening and adjusting accordingly.

Objective:
To demonstrate the process of installing a prehung door assembly quickly and efficiently.

Prerequisite Skills:
Familiarity and skills with basic hand tools: Measuring tape, level, rafter square, utility knife.
Familiarity and skills with pneumatic nail guns.
Familiarity and skills with circular saw.

Tools and Materials:
Measuring tape, 6-foot and 3-foot levels, rafter square, utility knife, pneumatic nailers, circular saw.

Vocabulary:
Rough opening (RO): Framed opening into which a door or window fits.
Jack studs: Vertical framing members that flank each side of a rough opening and support the header.
King studs: Full height vertical framing members that the jacks attach to.
Header: Horizontal framing member that forms the top of the rough opening. May be structural if the wall with the opening is a supporting wall.
Cross-leggedness: A condition when the two sides of the RO or the assembly are not in the same plane.
Prehung door: An assembly of finished jambs and an operating door that fits into a rough opening.
Hinge jamb: The vertical side of the prehung door assembly that the door is hinged from.
Strike jamb: (Also called the latch jamb) The vertical side of the prehung door assembly that the door closes against.
Head jamb: Horizontal part of the prehung door assembly.
Door stop: Finish trim inside the perimeter of the jamb that door closes against.
Door slab: The operable section of the door.
Reveal: The margin or gap between the door slab and the jambs.
Shim: Tapered piece of wood (usually made from a wooden shingle) that keeps the door assembly positioned in the rough opening.

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