Installing doors is almost a trade unto itself, as there are many different types and styles of interior doors. In this article, we will be discussing how to install a pre-hung, interior door, which closes into a jam and against the stop.
Make Sure You Have The Right Door
You need to have the correct door! Pre-built doors usually come in sizes ranging from 24” (2’-0”) up to 36” (3’-0”), are either right-handed or left-handed and usually come pre-hung on a jam. The measurement of the door is the measurement of the slab, also called a panel, and does not include the jam. So the rough opening (RO) for a 2-8 or (32”) door, will be about 2” wider than the slab, or 34”. This extra space is to accommodate the jam legs and any shims needed (more on shims later).
Once you have determined that you have the correct size door for the opening, you need to figure out which way the door will swing. Standing in front of a door, as if to walk through the opening, does the door swing left or right? If left, it is a LH door, if right, it is a RH door. Most doors will open against a wall. A good rule of thumb is to never install a door that swings over a light switch or outlet. Sometimes it’s unavoidable but houses are usually designed with the swing of doors in mind.
The first step of any good installer, is to step back and look at the big picture.
Ask yourself these questions:
- Where is this door being installed in the house?
- Does it sit alone, away from other door and window openings?
- Do multiple doors sit right next to each other?
- Are the finished floors installed or are you working over a subfloor?
- Is the door swing correct?
- What kind of trim will the door get?
Having all this knowledge before cutting, nailing or screwing anything, is always a best practice. For example, if determined that the door will be directly next to other cased openings, it is important that all of the doors are set to the exact same header height, so when you go to trim the door, everything lines up and looks right.
Installing A Door Over Finished Floors
If finished floors are installed, then it is likely you will need to cut the bottom of the jam legs to level the door and have both jam legs sitting tight to the floor. This can be achieved a few different ways, though I like to shoot a laser line across the top of the opening and then measure down to the finished floor on each side of the opening. Those measurements are what you need to cut the corresponding jam legs to.
Take note of where your casing legs and header will be on both sides of the door. Sometimes there isn’t enough room on one or both sides of the opening (like the inside of a small closet) to install full width casing, in which case you have to scribe the trim to the wall. Armed with all of the information you need to properly install the door, the process should go smoother than if you just wing it… though installing doors is more than just following the process exactly; it’s almost an art at times.
Remember that you are installing something that has to be plumb, level and square, into an opening and over a floor that are most likely not plumb, level and square. It can be a frustrating ordeal sometimes, but through experience, it becomes much simpler and more efficient. So let’s get to it and get some of that experience; it’s time to hang a door!
Hanging The Door
The first tool I use is a long level, to check the sides of the rough opening for level. I then staple shims directly to the framing material on the hinge side of the opening, at 3 points from top to bottom. These points are denoted by where the hinges are on the door, as it’s important to always put shims behind the hinges. I staple the shims to the framing lumber, using them to create a level plane for my hinge side jam to sit against. As I’ve already measured my opening and my door, I know that I have enough space to shim the hinge side level and fit the door in the hole, maintaining enough room to adjust my reveals on the strike side of the door.
*Remember to make sure that you will still have enough clearance between the floor and the bottom of the door before you make any cuts as there is only so much jam leg you can take off before you have to also cut the bottom of the slab.
*If installing over sub floors, where either carpet, hardwood, etc will be installed later- It may not be necessary to cut the bottom of the jam legs if flooring will be installed later. Typically you can shim one leg or the other up off the subfloor to bring everything level, and the flooring will cover any gaps. It’s good to know what type of flooring will be installed and how thick it is so you can be sure to not exceed those specifications.
After shimming the opening level, if installing over a finished floor, I set a laser line to exactly where I want the top of the jam to be. Then measure down on each side of the opening and transfer those measurements to the jam legs of the pre-hung door. I will lay the door on its side, hook my tape right to the top of the jam and measure down, square across and use a circular saw to make the cut.
The measurements might not be the same; if the floor is out of level – for example, one jam leg will get cut shorter than the other. When the door is set in the opening, both legs will sit tight on the finished floor and the header will be level. Now when you go to install your trim, you will have consistent reveals and a level header piece.
With the opening level and the jam legs cut to size, it’s time to put the door in the opening. I like to set the door where it will go, then hold the top of the hinge side jam in place with one hand and shoot a 15 gauge nail into the top of the jam, securing it to the framing. At this point I check to make sure my header is level and then proceed to nail through the jam and into the framing, avoiding the shims at this point and making sure that the hinge side jam leg is flat against all the shims as I nail. I’ll come back later and nail off all of the shims, once I know my reveals are consistent and correct.
With the hinge side secured, I jump over to the strike side of the door making sure it is plumb and the slab is hitting solid against the doorstop; then I shim that side level or square with the hinge side. Remember, all we are doing here is making a square box for the door to sit in. Sometime plumbing the door will require some cross-leg adjustments, meaning you may have to use your mallet to bump the top or bottom of each side of the jam legs into plumb with each other, nailing and shimming if necessary to hold those adjustments in place.
A level will tell you if you’re plumb, but I trust the sound and feel of the door closing on the stop. It should feel solid and sound like a single clap, but don’t test this until you’ve nailed the entire jam to the framing! On the strike side, I’ll always put a shim behind the strike, as well as multiple other points up and down the jam leg, securing the jam in place with nails, still avoiding nailing through shims.
Take A Look, Have A Listen
At this point I step back and and take another look at the big picture (something I do often while building/installing) taking care to check all the reveals between the slab and the jam. The reveals should be consistent at about 1/8” on the hinge side, strike side and at the header. I may need to add or remove some shims at this point (on either or both sides of the door) to make small adjustments in the reveals. Once everything is where I want it, I shoot a couple nails through every shim point on the jam to secure it in place and ensure it doesn’t ever move! Now you can give the door a good solid close and hear that sweet sound!
With the door installed plumb and level, all shimmed and nailed, closing tight against the door stop and not opening or closing by itself, it’s time to put some trim up, but that’s another article…
