Install door or window trim

1.1    Mark a reveal line 3/16" from the edge of the jamb to align the moulding.
This space will be visible, uncovered by the trim. Make this line on the three sides of the frame.

1.2   Check the mitre angles at the corners with two 12" test pieces cut at exactly 45°.

1.3    Hold the test pieces at the corner and you can see exactly how your trim is going to fit. If you see a gap, adjust the saw accordingly and cut both pieces at the new angle.

2.1    Stand the moulding against the wall the length of the door frame.

2.2    Mark the cutting line where the doorjamb markings meet, indicating the cutting angle.

2.3    Lay the moulding flat on the mitre saw base and cut the moulding at a 45° angle.

2.4    Using a level, position the moulding on the reveal line.

2.5    Drill small holes in the moulding at 12" to 16" intervals and tack in 1" finishing nails to the jamb and 2" nails to the wall.

3.1    Cut an angle that corresponds to the moulding installed on the jamb.

3.2    Using a level, position the moulding on the line marked on the jamb, adjusting the angle for a precise join with the moulding previously installed.

3.3    Mark the cutting line from the other corner where the marks on the doorjamb meet, indicating the cutting angle.

3.4    Lay the moulding flat on the saw base and cut the moulding at a 45° angle.

3.5    Using a level, position the moulding on the reveal line.

3.6    Drill small holes in the moulding at 12" to 16" intervals and tack in 1" finishing nails to the jamb and 2" nails to the wall.

4.1    Stand the moulding against the wall parallel to the other door frame length.

4.2    Mark the cutting line at the end of the head moulding, indicating the angle.
Leave an extra 1/32" for fitting purposes

4.3    Lay the moulding flat on the mitre saw base and cut the moulding at a 45° angle.

4.4    Using a level, place the moulding on the jamb and adjust the length or angle if necessary.

4.5    Using a level, position the moulding on the reveal line.

4.6    Drill small holes in the moulding at 12" to 16" intervals and tack in 1" finishing nails to the jamb and 2" nails to the wall.

5.1    Carefully adjust the corners and pre-drill the top of the head moulding 1" from the edge.

5.2    Nail the corners with 1/2" finishing nails.

5.3    Finish all nailing on the trim.

5.4    Countersink the nails using a nail set.

6.1    Mark a reveal line on the perimeter of the window frame.

6.2    Start with the head moulding using the techniques outlined above.

6.3    Cut the side mouldings and adjust the angles of the upper corners.

6.4    Cut the angle of one side of the lower moulding and adjust.

6.5    Measure and cut the angle of the other end of the lower moulding.

6.6    Slide the moulding into place and adjust until the fit is perfect.