The Hobo-Chic Project: How To: Install a Door Jamb & Hang a Door

A way to save yourself a few bucks is not to buy a pre-assembled door jamb, usually these kits cost anywhere from $60-90, whereas the materials in our project cost $47. We have also been able to save cost on some of our doors by buying ones from our local Architectural Clearinghouse which offers reused and salvaged materials. We have been able to pick some some standard 6-panel doors at the store for $18-22 depending on size.

Things Needed:

Tape Measure

Pencil

3 pieces of pre-primed MDF door jamb

16-20 ft of pre-primed MDF door casing, in the style of your choosing (amt. needed depends on sz of door)

Door

Hinges

Chop saw

Nails, hammer or a pnumatic nail gun

DAP, rapid drywall mud or DAP DryDex

Box Cutter, Chisel

Screwdriver or drill

Primer, brush, tray

Most doors are a standard 80“, which means the rough opening of your door will be a couple inches larger than this. You need enough linear feet to do 2 sides and a top. Most building stores stock in a 7 ft (84 inches) length, which means for your project, you will need 3 pieces.

Of course, the old carpenter`s adage to measure twice and cut once does apply, so make sure you measure your door before you pick up your materials (just in case).

Jamb refers to the trim which is inside your door frame, casing refers to the trim outside of your casing (aka the pretty pieces). As an additional finish, the head pieces of casing in our house are a different style. This is a personal preference.

In our house, we have used the following styles:
Casing: Moulding & Millwork, Casing MFPU8039
Head Casing: Moulding & Millwork, Architrave 5010

Jamb is fairly standard, here`s an example if you need one.

Head out to your favourite local home improvement store. The pieces you are looking for will be in Millwork section, and comes in a variety of styles, as well as primed or painted. We prefer to use primed MDF and then paint with our own primer. If you`re trying to match up existing trim, most existing trim will be a Colonial style but it may be helpful to have a photograph.

In order to find cut the head jamb, you need to know the width of your door. We will add a 1/4 inch total to the measurement of your door to give enough play for the door to swing open and closed on hinges (as every door should!). The easiest way to do this is to just cut the pieces square at the width of your door plus 1/4 of an inch.

However, we like to notch our door frames. This is a little more advanced, but we feel it gives us a door frame that will withstand the test of time.

To do this, you square the end of your jamb, cut a notch the same thickness of your jamb (5/8“: standard), to find the second notch, measure the distance from the first notch the width of your door plus 1/4“ (so if your door is 24“, then measure from the notch 24 1/4“ and this is where your second notch should start - 5/8“ thick).

In order to cut a notch, you need a piece of material 3“ to place between the saw fence and your jamb to hold the piece away from the fence, so you can set up your depth of the saw to cut 1/4“. Basically this jamb is placed on the fence to allow you to get to depth at the back of your piece.

The side jambs length can be calculated by adding the height of the door (standard 80“) plus 1/4“, plus gap spacing of 7/8“ for spacing at bottom & top of door.

Cut your side jambs to length calculated.

Take a minute and have a thought on which way your door will be swinging into your room, as this affects where you will put your hinges. Typically bedrooms and bathrooms will swing inwards towards a wall.

Measure 8`` plus depth of notch (1/4“) from the top of your jamb. Mark with pencil. This is where your first hinge will go. Attach your hinge using 2 screws and your screwdriver or drill.

Repeat the process for the bottom hinge, measure from the top of the first hinge 59“ down and attach this hinge.

Score around your hinge using a box cutter or a router if you have one (we obviously don`t). Remove hinge, rinse and repeat for the second hinge. Pay careful attention that you are just cutting in to the depth of the hinge but no further.

You should be left with hinge imprints that look a little something like this:

Chisel within the depth of the hinge (within your marks), so this will inset your hinge slightly, this is usually about 1/8“ or slightly less. Put hinges back into the now chiseled areas on your jamb.

Repeat this process on your doors, using a 7 7/8“ from the top of the door for the top hinge and 59“ from the top hinge for the bottom hinge.

Using your hammer and nails (sucker) or nail gun, tack the head jamb into your side jambs.

Place your completed door jamb within your rough opening. If it doesn`t fit, revisit your measurements as you may have taken a wrong turn somewhere along the line.

Measure from the floor to the notch for the length of the side casing. Cut boards to size.

Use 1“ nails to attach the casing to the jambs using a hammer & nails (sucker) or a nail gun NOT to the wall (yet).

Hang the door within the door jamb by attaching the hinges into the area you just chiseled out on your door. Add a piece of tape (we used painter`s tape) to be able to able to open & shut it (door knob tutorial coming up next).

Adjust the jambs and casing, by sliding them or pushing them until you have an even gap all the way around, and the door will open and shut freely.

Tack your casings into the wall using a hammer & nails (sucker) or a nail gun.

Measure from the outside of the casing to the outside of the casing to get your distance (and measurement) for the head casing.

Set saw to 45 degree angle and cut one end in a back cut, use measurement then to measure to make your second cut. Line up back of your cut to the outside of your casing and tack it in place.

If you want a pretty end piece to really finish your work, you can take the scrap pieces from the two cuts you just made, put your saw back up to straight 90 degree angle and cut on the intersection on the back side of your previous cut. This will form a little triangle thin piece which will be perfect. Try it on a couple pieces of scrap wood if you are having an issue with wrapping your mind around it.

For a finishing look, we use DAP caulking to fill in the joints and the nail holes with DAP DryDex (rapid drying drywall mud). Put a little on your finger, push it into the hole, rub off the excess. Let this dry over night.