Gateshead Airey Trial
Gateshead Housing Company is using Novabrik, a
dry-built brick cladding system, in trials to asses its
suitability for the external refurbishment of its stock
of airey-type, PRC (prefabricated reinforced concrete)
houses.
Airey houses were a feature of the post war building
boom with thousands of these “non raditional”
type of dwellings built throughout the country. The original design uses prefabricated, reinforced concrete columns to provide a structural framework
to support the floors and roof. A series of ship-lap
style concrete panels, tied back to the columns, form
the external envelope and give the building its
characteristic appearance.
The slender nature of the supporting columns
means any deterioration, through moisture ingress
or carbonation of the concrete causes a significant
weakening of the structure. As a result, Airey properties were declared defective under the
Housing Act of 1985.
Engineering design work for the Gateshead refurbishment as
been undertaken by multi disciplinary housing consultants,
Michael Dyson Associates. The work involves the introduction of
a completely new structural timber frame which makes the
existing columnar system redundant.
Explaining the system, Engineering Assistant Ray Bottomley, said. “The outer leaf of concrete panels is removed and a new load
bearing timber frame introduced. Although the existing concrete
columns remain in place, the new frame takes all the upper floor
and roof loading, making the old columns redundant”.
“The new frame helps creates an insulated cavity which is closed
off with ply sheeting. The outer skin of Novabrik cladding is then
fitted to vertical timber battens. It's as straightforward as that”
Added Mr Bottomley.
Novabrik Cladding comprises brick sized masonry units which lock together to form a weather-proof outer skin. The interlocking construction works in a similar manner to tiling, with units overlapping to prevent water from penetrating the wall. It creates a breathable skin that promotes free flow of air into the cavity, removing any moisture coming in from the outside.
The units are dry-laid in a conventional brick bond onto a polymer starter track which is fixed to the structural timber frame at approximately ground level. Every forth course of Novabrik is screw fixed to vertical timber battens to ensure vertical and horizontal alignment. The system requires no mortar or other wet trades and, according to the manufacturer, Acheson & Glover Group, is straightforward to install, needing skills more associated with joinery than brickwork.
The finished result is a building that looks like a newly built brick house. The Novabrik skin is only 75mm thick, so existing eaves overhang are not compromised, although in the Gateshead refurbishment, the roof was also re-tiled, complete with new soffit and barge boarding.
Another important feature of the Novabrik system is that it is
wall- hung and does not require its own concrete footings, as
would be the case in conventional brickwork re-cladding.
Bruce Davies, Senior Resident Liaison Officer for Gateshead LES
[Local Environmental Services] - the housing improvement
contractor for Gateshead Council, explained the background to
the choice of Novabrik. “Earlier trials had involved the use of an external render system and we experienced problems because of
the weather conditions on site. Novabrik gave us much better
control over quality and, because it can be fitted in virtually any
weather, it was a much better choice”
“We have also fitted new windows, doors, roofing and insulation,
together with major internal upgrading of internal facilities. The
works have been completed over a four month period and the
properties remain occupied by tenants throughout the
programme”, he added.
Gateshead Housing Company was also keen to improve the
overall appearance of the houses. Russell Urwin, Senior Contract
Administrator for Gateshead Housing said. ”We wanted our
tenants to be pleased with the look of their homes and Novabrik
has a very traditional looking brick appearance. It's also
recognised as an innovative, modern method of construction.
For us, it ticked all the boxes”.
The Gateshead Airey homes are being refurbished under the
Government's Decent Homes Initiative which requires that over
3.6m homes throughout the country are brought up to a
minimum standard of repair, facilities and insulation by 2010. If
successful, the Novabrik trials may lead to its widespread
adoption as a preferred cladding solution.
Originally developed in collaboration with Canada's National
Research Council, Novabrik is manufactured under licence for
the UK and Irish markets by building materials specialists,
Acheson & Glover Group.
Novabrik is also suitable for new-build projects and the
manufacturer claims savings in installation times of up to 50%
have been experienced, resulting in earlier occupancy and
overall reductions in contract duration.
