Civil Engineering Reference
In-Depth Information
Thermal properties
Thermal properties are rarely called
for in internal doors, though
conditions may need to be controlled
where the door separates rooms
intended to have vastly different
temperatures.
Thermal conductivity (W/mK):
●
hardwoods
country's stately homes often used
two pairs of heavy doors within the
thickness of massive masonry walls
with reasonably good results
(Figure 8.8).
Maintenance
The fashion for stripping painted
framed doors by dipping them in
caustic solution has ruined many a
sound example. The timber may
shrink unevenly and crack, the rails
move away from the stiles and almost
certainly the wedges loosen, leading
to warping, not to mention the
patches which become visible over
cut-out knots (Figure 8.9). Old doors
which were intended to be painted
should be kept painted.
Durability
Since there are no external weather
conditions affecting internal doors,
the most likely major influence on
their durability is resistance to impact
damage in heavily trafficked routes.
In hospitals, for example, it is not
unknown for doors to be opened by
trolleys and beds being pushed
against them. The former Property
Services Agency were said to have
had problems with internal doors in
barrack accommodation where the
army boot was the preferred method
of opening them. Warping and
twisting of leaves in areas of different
hygrothermal conditions have
already been referred to. On the other
hand, where conditions of use are not
severe, door leaves can last
indefinitely.
Steel sheet doors can dent
relatively easily, and the dents are not
removeable. In similar vein, although
melamine finishes are highly
resistant to wear and tear, they crack
under severe impacts; they are not
repairable and must be replaced.
Painted timber, on the other hand, can
be repaired.
0.15
softwoods
0.13
●
●
aluminium
160
steel
50
●
Fire
Those doors which specifically need
to possess fire resistance are dealt
with in Chapter 8.2.
See also Chapter 6.3 for doors in
partitions adjoining a protected shaft.
Noise and sound insulation
The banging of internal doors is one
of the noises easily transmitted to
adjoining dwellings. The best remedy
is to fit a suitable door closer.
However, laboratory studies have
shown that simple buffers round the
door frame can also give an
appreciable reduction in noise from
moderate slams, but are less effective
against hard slams
(223)
.
So far as noise transmission
through internal doors to adjacent
spaces is concerned, the average
lightweight hollow cored internal
door with wide clearances provides
very little sound insulation - perhaps
as low as 10 dB, depending on
construction and the size of the gaps
between leaf and frame or lining.
Close fitting heavier doors may give a
little more (Figure 8.7).
Improvements may be effected by
the fitting of draughtstripping to
reduce the size of air gaps, but this
will tend to make the door difficult to
open. Where there is a paramount
need to improve sound insulation
between rooms, and a doorway is
essential, consideration might be
given to the construction of a lobby,
with doors at each end. Lining the
lobby with sound absorbent material
is worthwhile. The larger the lobby
the better. Hanging doors on each
face of a thin partition is rarely
worthwhile in sound reduction terms
let alone convenience in operation,
though the builders of some of the
Figure 8.9
This softwood door has been stripped by
immersion. Movement can be seen in the
displacement of the tenon and the opening
of the stile-to-rail joint
Figure 8.8
Doorway through
a massive masonry cross-wall
