Civil Engineering Reference
In-Depth Information
Figure 5.24
Motorised rolling security shutters in a high risk suburb
Figure 5.25
Large-slat rolling shutters with vision panels
on an industrial building
practice demands separate provision
for thermal insulation within the door
structure itself. Since doors can form
a large proportion of the external
envelope of some industrial buildings
(Figure 5.25), it may be worthwhile
considering retrofitting thermal
insulation.
For rolling shutters used for
protection of domestic windows and
doors, as already noted, slotted
ventilation may be provided; there is
therefore no additional thermal
benefit from this kind of shutter.
See also the same section in
Chapter 5.1.
Strength and stability
Designs for doors vary so much that
there is little useful information that
can be provided. Specifiers will need
to consult manufacturers.
Doors can be tested for impact
damage risk in the same way as other
building materials.
External shutters are sometimes
specified for high risk domestic
premises. Installations are
proprietary, and usually consist of
steel slats, which may be perforated
to provide ventilation when in the
closed position (Figure 5.24).
Dimensional stability, deflections
etc
For coefficients of linear thermal
and moisture expansion etc, see
Chapter 1.2.
Fire
Shutters of the rolling pattern may be
required to provide resistance to fire.
Testing is the only sure guide to
behaviour. Collapsible gates of
course have no fire resistance
whatsoever (Figure 5.26).
Automatic shutters on escape
routes should not be triggered by
smoke, only by fusible link.
Weathertightness
Perhaps the main difference from
smaller doors will be the larger areas
being more vulnerable to buffeting
wind pressure. Of course there may
be special needs, too, for different
kinds of traffic.
See also the same section in
Chapter 5.1.
Noise and sound insulation
This property will depend on two
factors, the weight of the materials
covering the opening, and the amount
of air leakage or gaps. Even the better
installations cannot be expected to
achieve much more than around 20
dB (A).
Thermal properties
For new buildings, the regulations
suggest a U value of 0.7 W/m
2
K for
vehicle doors, a figure which in
Figure 5.26
Collapsible gates have
no fire resistance. Nevertheless,
they do have a role in security situations
