Door Installation Made Easy
We asked longtime professional trim carpenter Jerome Worm to show us his best door-hanging tricks.
Check the Rough Opening
Make sure your door is going to fit into the opening. Measure the height of the opening, and then measure the width at both the top and the bottom. Next, check each side with a level. The sides don’t have to be perfectly plumb (they rarely are), but they do have to be close enough to allow adequate room for your door.
If your rough opening is 1/2 in. bigger than your door but the sides of the opening are each 1/2 in. out of plumb, that opening is not big enough to hang your door properly. Finally, check to see if the walls are plumb.
Level the Floor
The most critical step of any door installation is making sure the bottom of each doorjamb is at the proper height. If you’re installing a door on a finished floor and the floor isn’t level, you’ll have to cut a little off the bottom of one of the jambs.
Use a level to check the floor. Rest a level across the opening and level it with one or more shims. Mark the shim at the thickest point, and measure the thickness of the shim at the mark. That’s exactly how much you’ll need to cut off the jamb at the opposite side of the opening.
Cut Down the High Side of the Jamb
Our pro uses a circular saw to cut down jambs when they need it. He installs an 80-tooth blade in his saw to prevent tearing out the wood veneer. It’s easy to cut off the wrong jamb, so make sure you cut the jamb that rests on the high side of the floor. It’s the one on the opposite side of the opening where you marked your shim. A rafter square works great as a saw guide.
Attach Temporary Blocks to the Jamb
To hold the doorjamb flush with the drywall before permanently fastening it, our pro attaches temporary blocks to both sides of the jamb. He uses scrap lumber to make five 4-in. to 5-in. blocks. Then he attaches each with 2-in. 18-gauge brads. He nails three blocks on the latch side and two on the hinge side (the door slab keeps the middle of the hinge side rigid). Keep the blocks away from the hinges so they won’t interfere with shimming. The casing will cover up the nail holes when the blocks are removed.
Use Blocks to Level Jamb Bottoms
If you’re installing a door on an unfinished floor and need space under the jambs for carpet, just rest the jambs on temporary blocks while you’re hanging the door. Adjust the size of the blocks so the bottoms of the jambs are on a level plane. Our pro leaves a space under the jambs of anywhere from 3/8 in. to 5/8 in., depending on the thickness of the carpet and pad.
Nail the Blocks to the Wall
Set the door in the center of the opening. Make sure you have a consistent gap between the door slab and all three sides of the jamb. If the bottoms of the jambs were properly cut beforehand, the gaps will be consistent, the top jamb will be level and the sides will be plumb.
Double-check the hinge side for plumb before nailing the blocks to the wall with a couple of 2-in., 15-gauge finish nails. Nail the hinge side first, and then recheck the gap around the door slab before fastening the blocks on the latch side. The blocks will allow enough wiggle room for fine-tuning before the jamb is shimmed and nailed to the framing.
Check Gap at Door Stops
Before installing any shims, remove the plug that holds the door slab in place, and make sure the door opens and closes properly. The door should come in contact with the door stop evenly the whole length of the stop. If one side of the door hits the stop first, you’ll have to adjust the jambs by moving either the top side or the bottom side of the jamb in or out, depending on which part of the door hits first.
Shim Behind Hinges
Remove the center screw from all three hinges, and slide shims behind the empty screw hole, starting with the top hinge. Fill the whole gap evenly between the jamb and the framing or you’ll pull the door out of alignment when you drive in the screw.
If the framing on the rough opening seems to be twisted one way or the other, position your shims so the jamb stays perpendicular to the wall. Once the shims are in place, make sure the jambs are still flush with the drywall (if your walls are plumb).
Recheck the gap between the slab and the jambs. Recheck the gap between the door slab and the door stop. If this gap is more than 3/8 in., it’s best to split this adjustment between the hinge-side and the latch-side jambs; adjust the jamb so it’s only halfway corrected. And finally, nail the shims into place using three 2-in., 15-gauge nails.
Install Longer Screws in Each Hinge
Replace one factory screw in each hinge with a longer screw. Drive the screw in very slowly the last few turns, and pay close attention to the jamb. You don’t want to suck the jamb in and throw off the alignment of the door. Check all the gaps, and open and close the door after you install each screw.
Make sure the screws penetrate the framing a minimum of 1 in. The gap between the framing and the doorjamb shown was about 1/2 in., so our pro installed 2-1/2-in. screws. Don’t use drywall screws—they’re brittle and won’t hold up to years of abuse. Buy construction screws instead, and try to find some that are close to the same color as your hinges.
Secure the Latch Side
Insert and secure shims 4 in. down from the top of the door and 4 in. up from the floor. Nail the shims the same way that you did on the hinge side.
Our pro has repaired doors that were slammed shut so violently from the wind that the jamb on the latch side was knocked several inches out of place. To prevent this problem, he installs a long construction screw behind the latch plate. He pre-drills and countersinks a hole in the corner of the latch plate space so it won’t interfere with the latch plate screws. He doesn’t use longer screws in the latch plate holes because they’re too close to the edge and can split the framing lumber.
Next, check out our story on the right way to install a window.
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