designers'
comments
The absence of absorption
material
in the Type W
eliminates the danger of 'trapped or held' water freezing
in extreme weather conditions and
spalling of the masonry taking
place.
(Test ASA/1990). The
Type W should not be
confused with
single-
function systems which do not offer the benefit of bi-pressure
extraction and
performance. The NHBC Standards Extra Issue 21,
2001, Illustrated the Type W with its integral grille,
stating
preformed models are preferable to open perps, as grilles prevent
entry of insects into the structure and weeps that do not taper are
less likely
to block. The latest BS
5628-3:2001
advises:
"Proprietary devices may be installed to form weepholes. They
may be
designed to drain the
cavity but prevent the
ingress of
wind-driven
rain."
The Type W provides all recommended functions
in terms of air, wind, rain and insect control and can
also be used as
a perp ventilator.
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use
Cavity wall weep, designed to provide an outlet drain to
discharge water from tray/DPC. Also ventilator as required to ventilate
wall cavities, insulated cavities and suspended floor
situations.
introduction
DPC and cavity
tray installations require weeps to discharge collected water from the
building fabric. BRE and NHBC recommendations refer to weeps with
conventional lintels also. Ventilating of wall cavities, suspended ground
floors and enveloped construction is necessary to avoid interstitial
condensation and remove the risk of moisture-laden air condensing and
causing dampness and subsequent deterioration. Type W weepvents ensure
water is
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removed from the cavity whilst also encouraging the wall to
breathe.
type W
weepvent
The type W weepvent is the
first specifically conceived dual-purpose weep and vent. Aesthetically and
practically designed with a functionally inclined front, the Type W is
finished with an insect-resistant grille. Air can easily enter the grille
which, by virtue of its shape, provides a superior overall air intake
area. Internal baffles control any water which may enter and encourage
discharge via the weep outlet on the projecting underside of the Type W.
The Type W removes the risk experienced with open-ended weeps and vents -
often as overlooked but important factor on exposed high-rise buildings.
Used as a ventilator, the Type W ensures superior performance, and allows
the wall to breathe. Used as a weep, the Type W encourages correct water
discharge, as the design makes use of positive and negative air pressures.
Wind-driven rain deflection is maximised because the grille is set
forward. This position also prevents insect fostering within the body of
weep/vent. |
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the type W extension
duct
The extension duct is designed
to push-fit onto the Type W, to form a 305mm straight-through ventilator
and weep.
protection when
building-in
An optional front cover
is available to ensure cleanliness when incorporating in rendered work.
Covers are florescent and coloured for obvious identification. They are
easily removed upon completion of render work.
sizes
Standard size 105/115mm
x 65mm x 10mm plus lock fit wedges.
Extension duct 200/225mm x 65mm x
10mm.
Overall combined length 305mm.
Standard Type W provides 390mm˛
free air space.
material
BS
polypropylene.
colour
Available in colours
to harmonize with popular mortar shades: Grey, black, beige, brown,
terracotta, white, clear. Special colours and shades available.
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bill of
quantity
wording
Dual purpose
Type W weepvents from Cavity Trays of Yeovil, Somerset BA22 8HU (01935
474769).
Colour = ......... Introduce Type W units into perp joints to
facilitate discharge of water from all discharge cavitrays and all
lintels. Observe spacing recommendations.
Total number =
.......
Alternative: Install extended version Type W weepvents (basic
unit plus extension duct) to every third/fourth perp joint in positions
indicated.
Total number = ........
Request liability/conformity
document upon completion.
building
regulations
Building Regulations,
British Standards and NHBC requirements may be satisfied with use of this
product.
See page listing references.
ordering
See inside back
cover for immediate service throughout the United Kingdom.
Merchant
distribution network.
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phone
01935 474769 fax 01935 428223 email
enquiries@cavitytrays.co.uk