How To DIY Install A Pre-Hung Door: Tips And Tricks For Flawless Results

For many DIYers, installing a pre-hung door exists on the fringe of their confident skill set. Sure, they can likely get it functional, but getting a door plumb, sturdy, and looking its best can often seem best left to a professional. Quality doors can get pricey, after all, and you don't want minor missteps costing you time and money. Still, you shouldn't doubt yourself! Though the idealized final result might seem daunting, you can DIY install a pre-hung door with flawless results by following these tips and tricks. This project can be straightforward as long as you have the right tools and a patient commitment to accuracy.

Once you have your door and are staring down the rough opening, you can choose your tools. A simple trick most DIYers can pull off is to opt for a door installation kit, like this E-Z Hang installation kit. The brackets attach the door jamb to the studs with a sliding system that doesn't require shimming, a helpful shortcut for a novice needing flawless results.

If you want to go the traditional installation route, you'll need a few packs of shims, your drill, 2 ½-inch or 3-inch construction screws, a 4-foot or 6-foot level, and a hammer or, for speed and simplicity, a brad nailer sporting some 2 ½-inch nails. While the project can be an easy one-person job, a helper could be useful for holding the door in place as you secure the sides, and it never hurts to have a second pair of eyes to help you avoid common mistakes when hanging a door.

When looking at your rough opening and determining how your door will fit, you have to check for a level floor. If the floor isn't level, the jambs won't rest evenly on it, screwing up the head jamb's alignment and the door's ability to close. Put your level on the floor just in front of the frame to see if one side needs to be lowered or raised.

If the hinge side is lower, one trick is to use a shim to raise the level on that side until the bubble is dead center. Mark that height that you had to raise the level. You can then either raise the hinge side with shims underneath, or cut that amount of space from the opposite jamb (the strike side). If the latch jamb is lower, you don't have to do anything right now.

Dry fit the door in the rough opening to see where you'll have to shim and whether you'll have to cut off some of the door jamb to fit the opening. Check if the rough opening leaves a significant gap between the stud and jamb requiring more than two shims. Take the door out, and adjust the opening as needed. For large gaps, install wood blocks (e.g. 1-by-4 pieces) to the stud to bring the mounting points closer to the door jamb. If putting blocks on the hinge side, install some of your blocks where the hinges will sit. You'll shim behind those points later.

With the floor resolved, you can level the hinge side of the rough opening to ensure a straight installation. Put your level against the stud (starting at the bottom) to check if it's plumb. If it isn't, put a pair of shims behind the level until the bubble is centered. Importantly, always run the two shims with opposing tapers so they maintain a face parallel to the stud and don't twist the door jamb once secured. Slide the ends closer together or further apart to adjust their thickness.

Nail the first set of shims into place. Then, move the level up the stud and use the same method to put shims at the middle and top hinge locations. Place your door into the opening to see how you did. Put the hinge jamb firmly against the shims and check that it's level. With your level as a straightedge, look for gaps between the level and jamb indicating warps in the frame, and add more shims as needed. If your door slab is attached to the frame, a simple trick to hold the frame in place as you do all this by yourself is to open the slab 90 degrees and slip some shims under it to level it.

When putting the door in the rough opening, you must make the jamb flush with the drywall, or you'll have serious issues installing the door trim at the end. An easy tip to ensure it's perfectly aligned is to tack a board across the doorway opening near the top and push the door frame in until it's snug against it, ensuring the edge of the jamb and the drywall surface are level. Alternatively, you can put small blocks (e.g., 4-by-4 pieces of plywood) at points around the perimeter to make the jamb flush at several points. Be careful not to put them where you plan to shim, though, as you don't want them in the way.

If desired, you can also install some blocks on the other side of the door to keep the door frame locked into the rough opening and make it easier to work with. You only need a few pieces of wood on either side. As you're installing them, ensure these blocks only cover the jamb and not the door, as you'll need to open and close it throughout the project.

Tack the hinge jamb into place, starting at the top where you have it flush with the wall. Work down the jamb, adding nails to the hinge locations over the shims and checking that the jamb is plumb as you work. Then, fix the jamb securely with construction screws at each set of hinge shims. You can drill straight through the door stop and shims and into the stud. To prevent splits in the wood at any point and improve the joint quality, drill pilot holes before installing your screws. For a smooth finish to your screw holes, use a countersink bit to get the head below the surface of the stop so you can fill it with wood filler and paint over it later.

Alternatively, you can secure the screws through the hinges. A common method many use when installing pre-hung doors with screws, this trick has you removing the middle screw from each hinge and replacing it with a longer screw that can go through the jamb, shims, and stud. Use a screw with the same color as the hinge to conceal it perfectly. Just be sure to go through the hinge hole closest to the stop to give you the best bite and anchor into the stud, making sure not to overtighten.

After securing the hinge jamb, you can move over to the strike jamb. Here, you'll use the reveal (the slim gap between the slab and jamb) as your guide. There should be a roughly ⅛-inch reveal, and as long as your hinge side was perfectly level, an even reveal at the top and latch sides will mean your door is correctly installed.

Check the reveal at the top jamb and cut the latch side down or bump it up with shims to get the reveal even. Then, adjust the reveal on the latch side, adding shims wherever needed to make the spacing perfect and avoid having to fix a sticking door later on. Install a nail at the top of the jamb to hold it in place. Shim the latch side, checking the reveal as you go. Once it's level and the shims are adjusted as needed, you can nail them into the studs.

Finish up by removing the excess of the shims protruding past the wall. Cut them with a multitool, or score them with a razor and snap them off. Add your door knob and strike plate. Complete your job by installing your trim, filling the nail holes, and caulking the seams for a flawless finish, using a paintable acrylic latex caulk to ensure your final product looks its best.