What Is a Pre-Hung Door?
A pre-hung door is a slab door that is already attached by hinges to a three-sided doorframe. It is sold by the manufacturer as a complete package and “ready to go,” though some may need additional features. More expensive than a slab door, a pre-hung door is a mostly self-contained unit with a frame that fits into a prepared doorway. Upon sale, pre-hung doors are tightly bundled into their included frames with polyester tension packing straps and plastic spacers to prevent them from shifting or twisting during shipment. The rule of thumb: If you already have a prepared doorframe with casing and trim, you should not purchase a pre-hung door. The only exception is if you intend to remove all of the trim and casing to the bare studs.
What Is a Slab Door?
A slab door is a basic, stripped-down door that does not include a frame. It is the responsibility of the do-it-yourselfers or installer to attach the slab door to an existing door frame or to create an entirely new door frame. Slab doors can be purchase with or without a pre-cut hole for the doorknob. If the existing door frame is so damaged or warped as to make it impossible to hang a slab door, it is usually easier to demolish that entire door area, frame included, and start from the beginning with a pre-hung door. For exterior walls, it is usually better to install a pre-hung door. Pre-hung exterior doors come weather-tight off the shelf, with no need to do anything else to make them tight-fitting. By contrast, unless you are highly experienced, it can be difficult to install a tight, weatherproof exterior slab door. Pre-hung doors make this an easier process for do-it-yourselfers.
Cons
Pre-hung doors are heavy and hard to manage. Weighing between 50 and 100 pounds, a pre-hung interior door with a hollow core slab is the lightest pre-hung door you can buy. Even if weight is not an issue, a pre-hung door is bulky and unwieldy to move. Pre-hung exterior doors easily weigh over 100 pounds and require two strong people to move them. Also, if you have a small vehicle, transporting a pre-hung door is usually not an option. Pre-hung door installation may seem simple but it can be difficult to get it correctly positioned. While you do not have to worry about the exacting task of hanging the slab to the frame, you still have the exacting task of fitting the pre-hung unit as a whole into the door opening. Pre-hung units, like all doors, require shimming. Even a pre-hung unit can be installed improperly so that swing and closing are impaired. Also, keep in mind that you still need to finish all of the work around it: drywall, painting, and installation of trim plus staining or painting.
Slab Doors: Pros and Cons
Pros
When saving money is of critical concern, you may want to explore the possibility of installing slab doors since they often cost much less than pre-hung door units. Slab doors provide you with much more design flexibility than pre-hung doors. For example, if you find an antique or unique door that you want to re-purpose for your own house, you can do this with a slab door. Architectural salvage doors nearly always come in slab form, yet rarely as pre-hung units. When installing an interior door, you may want to think about using a slab door rather than a pre-hung door unit. Interiors are more forgiving environments for imperfect installations, as weatherproofing is not an issue. Slab doors lend themselves better to smaller installation quantities. When you are installing only one or two interior doors, you will have the extra time and patience to devote to this more difficult process.
Cons
Slab door installation requires a steady hand, a good eye, and plenty of practice. It is easier to install a slab door if you are doing an exact, one-for-one installation in which the new door is the same size and configuration as the old door. But if there is any variation in the door size and configuration, it will be difficult to make it hang right. If your building skills are shaky yet you still want to install a slab door, you may wish to use a new slab rather than a recycled slab. A new slab door will be flatter and truer than a used door. Recycled slab doors usually need extra work, such as planing, sanding, and straightening.
