Summary
Trimming a door requires careful measurement.
It is recommended that you enlist the help of
a willing friend before you embark on this task.

	1	Measuring the frame
	2	Checking the vertical edges of the frame
	3	Before you buy a door
	4	Removing the old door
	5	Checking the door against the frame
	6	Marking the door height
	7	Marking the door width
	8	Cutting the door
	9	Plane the stile edges
	10	Planing the top and bottom of the door  

	
Tools
Tape measure, door wedges, pencil, ruler, saw, plane,
medium grade glass paper.

Materials
Door, hinges, screws.

Step 1 - Measuring the frame
Measure the frame carefully in three places for both
height and width. Measure the two diagonals. If the
diagonal measurements are not equal, the frame is
not square.   

Step 2 - Checking the vertical edges of the frame
A slightly warped frame can still be used if the
hinged side is plumb. The other side of the door
can be trimmed to fit.  
 
Step 3 - Before you buy a door
Doors come in several standard sizes, which should
correspond with your frame. Exterior doors are
usually bigger in most dimensions. Check that your
current door corresponds with a size from your local
supplier, or is only slightly smaller. The amount you
can trim off will depend on it’s construction, check
the guarantee with your supplier for the maximum
measurements.`11`1

Step 4 - Removing the old door
You will need someone to help you with this process.
Open the door at 90 degrees. Slowly begin to loosen
the screws. Place wedges beneath the door and get a
friend to hold it steady. Remove the screws from the
bottom hinge and all but one of the top set. Remove
the last one slowly as your partner holds the door
steady.

Step 5 - Checking the door against the frame
The door should have a clearance of 2mm for a flush
door 3mm for a panelled door  on the top and sides.
Check with the manufacturer’s instructions for the
correct clearance from the floor. It should be
between  3mm and 5mm.

Step 6 - Marking the door height  
You need to mark the relevant clearance on the door.
On flush doors an equal amount should be taken off
the top and bottom. For a panelled door  take the
excess only from the bottom of the door.

Step 7 - Marking the door width 
Hold the door against the frame from the inside
and mark the locking jamb against the door. Remove
the door and measure an extra 4mm in from your mark.
This second mark represents the correct width of
the door.

Step 8 - Cutting the door
You are now ready to cut the door along the marks
you have made. If you need to cut off at least 12mm
it is best to use a saw rather than a plane.  Always
saw off 2mm less than your mark and finish off using
a plane. This will ensure that you can trim the door
precisely.
 
Step 9 - Plane the stile edges
Always plane towards the centre of the door. Stop
at regular intervals and hold the door against the
frame to make sure you do not take off too much.
Create a slightly beveled edge tilting towards the
doorstop on the stile edges.

Step 10 - Planing the top and bottom of the door
Use the same method to plane the top and bottom
edges. Finally sand the cut edges with medium grade
glasspaper, to ensure a smooth finish.