Sawston Village College Science Wing, Cambridge
Cambridgeshire County Council
A new science wing built in two phases around the 1,004-pupil
college’s teaching terms, to contain eight classrooms.
Type of contract:
H+H UK’s Plus Blocks using the Thin-Joint system
meet the acoustic requirements internally and thermally insulates the
external walls for a fast-track construction programme. After using on the
first phase, this construction provided the advantage of speed against phase
two’s summer holiday deadline.
Hall Contracts of Norfolk
The extension provides eight new
classrooms to develop the college’s
specialism in teaching the sciences
to 11-16 year-olds. The first phase to
create five classrooms over a 700m2
floorspace was completed within
37 weeks by the Christmas holiday of
2008. The second phase to create
three classrooms over a 450m2
floorspace was completed within
27 weeks by the start of the summer
holiday. The fittings and furnishings
are installed during the holidays.
Product used/aircrete specification:
Standard Grade Plus Blocks 215mm with
the Thin Joint System.
n Internal separating walls – 6m-high of
solid aircrete blockwork to the pitched
roof apex using 7N/mm2-rated Plus Block
(610mmx215mmx200mm) and the
Thin Joint System. Murfor prefabricated
stainless steel horizontal bedjoints every
2nd course. After using a three-coat
plaster system at 6-8mm thickness on
the first phase, the result was improved
on the second phase by using a 10mm
single coat spray plaster by Lafarge.
Spray plaster applied beyond suspended
ceiling levels to maintain acoustics.
n External cavity walls – 6m-high cavityconstruction
walls using Plus Block
(610mmx215mmx100mm) and the
Thin-Joint system with 17mm
Kingspan Kooltherm insulation boards
plus 100mm facing bricks. Stainless
twist ties for lateral support within the
118mm cavity. Concrete ring beams on
top spread the load for the 3.6N/mm2-
strength Plus Blocks.
Build time (blockwork):
6 weeks. Some 1,617m2 of aircrete in use.
Reasons for choosing
For a Modern Method of Construction,
the product’s sustainability in terms of
production, waste control, packaging and
aircrete consists of 80% pulverised
fuel ash waste recycled from power
stations that would otherwise be destined
Quality of productivity on site:
For accuracy in the finish, which is
essential for non-toxic spray plastering.
The accurately-flush wall facing possible
with the Thin Joint System enables 2mmthin
spray plaster to be used, which doesn’t
contain any toxic gypsum.
Speed of build:
The Thin-Joint system enables the structure
to be erected faster and to a better quality,
allowing follow-on trades to start work
sooner in a weatherproof environment.
The walls are specified to achieve a
minimum acoustic insulation level of
49dBRW, because the BB93 requirement
is in the range of 40-45DnT(Tmf,max).
“The Thin-Joint system’s mortar for
each course dries within 10 minutes,
so we are building the 6m-high walls
much quicker than I’ve ever known
for traditionally mortared concrete.
I’ve been in the trade since 1973.
The Thin-Joint mortar is also good for
temperatures below that of traditional
mortar, which was important during
the especially cold winter.”
Stuart Lovesey, Site manager,
“While most masonry manufacturers claim general acoustic insulation performance for
products in housing, quantifiable substantiation of their performances was difficult to
pin down against the BB93 standard for schools. From this first experience of aircrete,
I will certainly specify it for future projects.”
Matthew Huckelsby, Project manager, Capita Symonds
Having a 0.15W/m2K U-value for thermal
insulation, enabled the external wall
specification to be lenient in other details
such as the windows and doors. This
thermal rating also enabled the external
wall cavity to be narrower than for concrete
breezeblocks, freeing up more floorspace.
Health & Safety:
The aircrete product presents minimal
risk on site, especially in terms of its light
weight for manual handling. This is not
only important to the builders, but also
to the architects because they are legally
liable for the H&S of handling the specified
products on site.
Client’s use of the completed walls:
Aircrete is an acceptable direct substrate
for the fixings of load-bearing fittings such
as shelves and cupboards, as well as for
heavy plant such as heaters.
For enquiries call
Tel: 01732 886444
or email: firstname.lastname@example.org
Kent TN15 9HZ
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