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site operatives and filled by pumping workable
concrete. Construction is fast. Typically, an
experienced team of four can erect and
concrete the walls of a three-bedroom
bungalow in just one day. The resulting
construction provides both structural capacity
and thermal insulation. The thickness of the
concrete, available from the various systems,
ranges from 100mm to 300mm. ICF can be
designed to enable significant structural
capacity both as un-reinforced and reinforced
walls depending upon the design loadings.
The insulation can be varied to provide for
U-values in the range of 0.11 to 0.35W/m
2
K.
Almost any finish or cladding system can be
directly applied or fitted to an ICF wall.
In addition to high levels of thermal insulation,
ICF structures have very low air infiltration rates,
almost all of which is accounted for by window
and door openings. Consequently, there is very
little heat loss due to air changes and this
boosts the thermal insulation effect.
ICF Growing in UK
Both EPS and XPS are closed cell forms
and have very low water absorbency.
The core is specified as a highly workable
concrete. This results in a low risk of voids.
Widely used in the USA, Canada and Continental Europe, the
Due to the permanent presence of the
insulation, both during construction and under
use of insulating concrete formwork (ICF) is growing in the UK operation conditions, the concrete undergoes
particularly with the self build sector. Guy Thompson, head of
more controlled shrinkage and thermal strains
and, as a result, experiences very little
architecture and housing at the Concrete Centre, reports.
shrinkage cracking. These factors combine to
produce structural walls that are inherently
CF, also known as permanently configurations and a number of proprietary resistant to flood damage. This is an
I
insulated formwork (PIF) is an systems, some of which have independent increasingly important consideration for
innovative modern method of third-party assessments such as BBA and BRE buildings in many parts of the UK.
construction. ICF consists of or LANTAC
twin-walled expanded polystyrene certification and have
(ESP) or extruded polystyrene (XPS) panels, also been assessed
blocks, planks or composites, connected by for Robust Details.
plastic or metal connectors and filled with These are accepted
ready-mixed concrete. as demonstrating
The system combines the inherent compliance with the
strength of concrete with the excellent thermal relevant building
insulation properties of polystyrene to produce regulations.
cost-effective and durable structures. The The basic structure
polystyrene is used as permanent formwork for is typically erected by a
the concrete and is available in a variety of team of three or four
In addition, ICF systems provide some of the
inherent benefits of concrete construction,
namely, sound insulation, fire resistance,
long-term performance and robustness.
There is minimal waste during construction,
as off-cuts of polystyrene can be used
elsewhere and the ready-mixed concrete
can usually be supplied locally to exact
volume requirements.
Championed by innovative self builders,
the use of ICF is set to become more
widespread, due to its ease of construction
and wide range of benefits.
Images supplied by Beco Products Ltd
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