How to Install a Prehung Door
Prehung doors can make your life much easier, but you still need to know a few essentials in order to get the job done right.
Doors come in countless different sizes and styles—from modern, flush interior doors with standard dimensions to massive, traditionally designed entryways. By comparison, there are dramatically fewer installation methods; in fact, there are only two. A door is either prehung in its own jamb, or it’s not. Installing a prehung door is considerably less complicated, but that doesn’t mean there’s no sweat involved. The following tips can help you avoid common setbacks.
It’s no problem to stray somewhat from the steps outlined here, but remember that no matter the techniques used, the goals always stay the same: Get the door jamb level and plumb; keep it flush with the drywall surrounding it; and maintain a uniform 1/8-inch reveal (the space between the door and the jamb).
When you set out to install a prehung door, begin by measuring the rough opening into which you are placing it. The opening should be one or two inches larger than the door itself. That wiggle room enables you to shim the door, bringing it to the level-and-plumb position critical to proper functioning.
Set the door into the rough opening. Has flooring not yet been installed beyond the threshold? In that case, shim beneath the door jamb to account for the height that will be added once the floor’s installed.
Next, make sure the hinge side of the door is plumb, meaning perfectly vertical. Having checked that the door is still centered within the opening, stabilize it by adding shims to both sides, near the top. Check the alignment using a level. If the door’s plumb, hold the hinge side so that it’s flush with the adjacent drywall, then nail into the jamb at the point behind which you added shims. Go on to place shims in a few more positions along the hinge side; check level once more; then nail through the jamb wherever you shimmed.
Close the door and confirm that its top portion is level. Don’t waste time reaching for a measuring tool, though, if you notice the reveal isn’t uniform between the door and the jamb. That’s a sure sign things are amiss. Make adjustments by shimming the latch side of the door. Shim less when there’s too little reveal; shim more when there’s too much of one. Continue tinkering until the reveal along the top is uniform.
On the latch side of the door, bring the jamb flush to the adjacent drywall. The reveal ought to be 1/8-inch here; if it’s not, then adjust the shimming you have added already near the top of the door on this latch side. Once finished, nail through the jamb where you have shimmed. Now place additional shims six inches from the bottom of the door, as well as above and below where the strike plate will go. So long as the reveal remains uniform, proceed to nail the jamb at each position where you have added shims.
To finish, go ahead and put a few more nails through the shims you nailed previously. Your pre-hung door is now level and plumb, with a uniform reveal!