Civil Engineering Reference
In-Depth Information
Fire
Cavity barriers need to be provided to
limit the sizes of cavities in certain
doubleskin curtain walling
installations, and in refurbishment it
is important to review their provision
in relation to the design of the
weatherproofing - in particular
whether the system relies on cavity
ventilation for drying off rainwater
penetrating the outer skin.
Non-ventilating glass blocks
should give around 1 hour's fire
resistance in relation to integrity, but
probably not in relation to insulation.
The manufacturer should be
consulted.
See alsoChapter 1.8.
Noise and sound insulation
A single skin of lightweight curtain
walling will only give sound
insulation approximately the same as
that for a single window.
Typical sound insulation values for
sealed curtain walling against traffic
noise are:
●
single glazing, 28 dB(A)
●
sealed double glazed units,
33 dB(A)
secondary glazing, 37-40 dB(A)
●
Against aircraft noise, double
construction gives about 3 dB(A)
improvement over sealed units.
Where there is the opportunity,
breaking up the internal cavities of
double construction and lining with
absorbent material may help.
Figure 4.32
A typical early curtain
walling installation with no thermal breaks in
the exposed framing and little thermal
insulation in the backup wall
Daylighting, solar control and
glare
Many installations of curtain walling
consist of solar control or tinted glass
which has reduced light transmission,
and which is highly reflecting. These
installations can produce significant
glare from the sun, sometimes
annoying or dangerous for motorists
(Figure 4.33). A discussion of the
geometry involved is to be found in
Chapter 1.6.
Curtain walling installations are
increasingly being specified with
some form of solar protection
integrated into the framework (see
also Chapter 1.7).
Light transmission of glass blocks
varies from around 50% to around
75% according to pattern and tint.
Figure 4.33
Glare from the sun reflected from this sloping curtain wall
