Civil Engineering Reference
In-Depth Information
Frames and linings
Internal doors depend for their
support on the strength and fixity of
the frame or lining, for the tightness
of their fit on the position of the stop,
whether it is integral with the frame
or fitted loose in a lining, and for the
effective operation of the latch.
Frames traditionally were fixed to the
partition with cut nails driven into
wooden slips placed in the mortar
joint; these fixings can deteriorate
over the years. Linings may be one
piece in thin partitions, but in thicker
ones may be split, sometimes
containing panelling in the reveals.
leaf. Leaves larger than 900 mm are
more prone to distortion, and, for this
reason, where clear openings of more
than
1 m are needed (eg for the passage of
trolleys), it is more usual to provide
two leaves which may be of equal or
unequal widths. Flush leaves are
perhaps less prone to lozenging, but
generally follow the above rule.
Door leaves may be tested for
strength from both hard body
(eg 50 mm steel ball) and soft body
(eg 30 kg dry sand) impacts (Figure
8.5), and from slamming.
Main doors to flats
The main entrance door to individual
flats requires special consideration
from the point of view of strength and
stability, although it does not have to
withstand the weather. As it is often
the only door leading to the outside, it
has to provide:
●
a barrier to intruders
●
Openings and joints
Door leaves may need to be fitted
with grilles, or to have gaps left under
the leaves to allow ventilation
between rooms, in order to feed air to
combustion appliances. These grilles
and gaps destroy most of the sound
and fire resistance of doors.
Figure 8.4
An internal six panelled door used by Nash
at Ffynone, in the early nineteenth century.
Two of the panels have split, probably as a
result of changes in the heating regime. A
near invisible repair would be possible by
removing the beads and glueing the splits.
Surprisingly for a heavy door, there is only
a single pair of hinges (Photograph by
permission of Earl Lloyd George of Dwyfor)
a means of escape for the
occupants in an emergency
access for the emergency services
●
on occasions a barrier to fire and
smoke
●
Main performance
requirements and defects
Choice of materials
As described above, most existing
internal doors, before the invention
of the flush door, were in wood, and
framed and panelled in either
European redwood or whitewood.
The more expensive doors were made
in imported tropical or European
hardwoods (Figure 8.4). Mahogany
was widely used in doors from about
the middle of the eighteenth century.
Door frames and linings have
almost invariably been in timber.
Where the doorway is pierced
through thick masonry, and the doors
are heavy, the linings may be very
complex, requiring careful
restoration. Some rather utilitarian
steel frames were used from the
1960s, often without lintels, which
do not call for particular comment.
In blocks of flats where there is no
Strength and stability
In general, framed softwood leaves
of up to 900 mm width should
possess adequate strength for normal
domestic situations, provided the
hinges are satisfactory and their
number relates to the weight of the
Figure 8.5
A test on a WC cubicle door. In this case it is the lock which is receiving particular attention
