A mitre joint cuts two pieces of material at an angle so they meet neatly at corners. Scribe joints are used for internal mitres to hide movement over time, with one piece cut square and the other cut to follow the contour. Different types of mitres include stop-end mitres to hide end grain, bastard mitres for unequal widths, and scarf joints to conceal joins. Raked mouldings are needed when surfaces are not square, with a different projection and drop from standard mouldings. Efficiency in installation involves measuring all areas first before cutting and installing all pieces at once.

1. Fixing mouldings

2. Mitres
A mitre is a type of joint where the
material is cut on an angle so that
two pieces meet neatly.
They are used when two pieces of
material meet at an angle, like
skirting at external corners,
architraves around windows and
doors, or where handrails change
direction at the top of stairs.

3. Mitres
To calculate the cutting angle, measure
the angle of the corner and halve it. That
is the cutting angle of the mitre.
The most common example is a
90 ̊corner.
Half of 90 is 45.
So cut both ends of the skirting or
architrave at 45 ̊.
When they meet, the two angles will add
up to 90 ̊
The same process will work for any angle.

4. Scribes
Internal mitres have a tendency to
open up over time. To hide this
movement scribe joints are used.
A scribe joint is where one internal
piece is cut square and butted into
the wall.
The other piece is cut at half the
internal corner angle and then cut
to the contour of the mould with a
coping saw.

5. Cutting scribes
The first step is to cut and internal
mitre. Make sure to cut the piece
long so that if the tip of the scribe
breaks you can recut the mitre
without wasting the entire length.
Start at the top and cut, following
the face of the profile with a slight
back cut so the front of the profile
becomes the leading edge.
For fine details it is easier to do two
cuts that meet instead of one very
tight turning cut.

6. Stop-end mitres
Stop-end mitres or return mitres are a way of
finishing moulding that hides end-grain.
Stop-end mitres are an external mitre that
goes into a very short butt join to the wall.
They are made by cutting a 45 ̊ external mitre
cut then cutting it off square. The offcut is
inserted to return back to the wall.
They are usually glued in place because fixings
splinter the timber.

7. Bastard mitre
When mitring two mouldings of
unequal width you must use a
bastard mitre.
The cut on each piece is a different
angle but the mitred edge is the
same length so they meet neatly.
Mark the width of the opposite
piece onto the first piece and draw
a diagonal line from the outside
corner to inside mark.
Cut to this line and repeat the
process for the other side.
1 2
3 4
5 6

8. Scarf joint
To conceal joins in lengths of
moulding a scarf joint is used.
The two pieces are cut with
opposing mitres so that they can be
lapped and fixed through the joint
on an angle.
This means that any movement in
the moulding will not completely
open the joint like a butt joint
would.

9. Nosing and aprons
Nosing is a rounded moulding type that
is used at the sill of windows.
They are finished with stop-end mitres
at each end so that the width of it is
even on the front and side of the
architrave, like in the diagram to the
right.
The apron is a low profile moulding that
sits below the nosing and spans the joint
from the nosing to the wall. It is finished
at each end with return mitres.

10. Raked mouldings
Off the shelf crown mouldings
cover the transition from plumb
walls to level ceilings.
When the ceiling is sloped this
poses problems at the top and
bottom of that slope because the
transition is no longer 90 ̊.
This means the moulding at the
bottom must “open up” to an
obtuse angle and the moulding at
the top is “closed up” to an acute
angle.
The Problem
Un-contoured solution

11. Raked mouldings
When mouldings cover transitions
between surfaces that are not
square to each other, raked
mouldings need to be developed so
they meet properly.
These mouldings can be developed
on site but it is often faster, but
more expensive, to have them
manufactured by a timber supplier.
Rake mouldings require the same
projection as the original moulding
but a different drop.

12. Fixing Mouldings
To fix timber mouldings to timber
frames regular brad nails and
adhesive can be used. Hand or
machine driven brads should be at
least twice as long as the moulding
is thick.
Fixing to steel frames may require
battening if the moulding needs
bradding. Otherwise the moulding
must be braced in position as the
adhesive dries.

13. Efficiency in Fix out
Compare these two scenarios.
One carpenter measures one wall
of a room, walks to the drop saw,
makes the cut, walks inside, installs
that piece, and repeats the process
for each wall of each room.
The second carpenter measures all
the walls in each room, makes a
cutting list, cuts all skirtings and
architraves at once, places them
around the job, and then installs all
at once.
The second carpenter saved time
and energy by doing less trips to
the drop saw.
By installing all pieces in the room
at once the second carpenter has
also cut down the time it takes
changing tools.
This may seem insignificant but
over the course of a working day
this can shave hours off job.