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Easy Home Improvement: Installing A Pre-Hung Door

by Gabby Hyman
Repair-Home Columnist

Not that many home improvement projects lead to despair and frustration, but there's no sugar coating the aggravation of hanging a new door only to find it sticks or swings open of its own accord. Experienced contactors who specialize in doors and windows can install a pre-hung door in short order, whereas a homeowner can descend into a frenzied misery of sanding, shimming, and hammering. Measuring carefully and specifying door dimensions and "handedness" to your supplier can save hours of trouble.

Even with a well-measured, precision pre-hung door, chances are good that you'll still need to adjust the framing and trimmers for a perfect swing. Not all houses sit plumb on the foundation, so your door opening may not have the same lines from top to bottom. And trimmers are not always installed in perfect parallels that hold square to the wall surface.

"It requires accuracy to put one of these in," says Tom Silva, general contractor for This Old House television. "If it's not installed right, it won't hang well." Silva says even a pre-hung door is a "precision instrument" that has to be adjusted for proper use.

Specify Your Door Swing and Opening

If you're ordering a door, be sure to specify the "handedness"-on which side do you want the knob when the door opens toward you. Typically, pre-hung doors are cut to fit openings 2 to 2½" wider than the dimensions you report for the jamb. For a standard door, set the shims to center the entire piece in the opening then adjust the shims to level the entire unit.

With a split door (where the jamb is in two pieces), you install the half that has the door attached to the jamb first, then insert the second half-jamb and cover both sections with stop molding (provided in the pre-hung kits).

If your walls are out-of-plumb, you may have to use a bob or level to plumb the hinge and latch jambs and shim them into place while you cut a small piece of wood to fill the space between the casing and the wall.

Give yourself up to two hours to do the installation. Tools required are a hammer, level, framing square, bob, and nails. The framing square is convenient to see if the trimmers are square to the surface of the wall.

About the Author
Gabby Hyman has created online strategies and written content for Fortune 500 companies including eToys, GoTo.com, Siebel Systems, Microsoft Encarta, Avaya, and Nissan UK.