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Under cover

Lafarge Roofing offers architects a comprehensive range of roofing products, each unique in style and design The almshouses in Padstow, Cornwall, were roofed with Cambrian Slates in 1988.

Today they have an attractive weathered appearance, blending into their surroundings to such an extent that it is almost impossible to believe that they are not natural slate.

In fact, Cambrian goes one better; it is a recycled product that is based on natural slate quarry waste. Redland designed Cambrian in 1985. It received BBA certification in 1987 and a Queen's Award for innovation in 1991.

Cambrian slates are made from waste slate taken from the spoil heaps of slate quarries in north Wales. The crushed slate - at least 60 per cent of the total - is mixed with stone, resin and glass-fibre reinforcement, and pressed in moulds to produce a strong and durable product with a life of at least 60 years. It is available in three colours which relate to the typical mid-grey and subtle purple colours of Welsh slates and to the typical light-green colour of Westmorland slates.

Cambrian Slates are particularly appropriate for sensitive areas such as National Parks, conservation areas and sensitive environmental areas such as Areas of Outstanding Natural Beauty. They have been used extensively in Dartmoor and Pembrokeshire National Park, and on buildings owned by the National Trust.

Cambrian is a single-lapped slate with a textured leading edge and surface. It has the following advantages over traditional slates:

a minimum pitch of 15 degrees, far lower than natural slate;

the consistency of a manufactured product - there is no need to sort and cut the slates before installation, and quality is guaranteed on all slates;

less than half the weight of natural slate, allowing the roof structure to be reduced;

with their single-lap interlocking design Cambrian Slates are faster to install than traditional slates; and lthe unique three-point fixing means Cambrian is suitable for even the most exposed sites.

A comprehensive range of dry-fixing and roof-ventilation systems is available for use with Cambrian Slates. These systems are designed to provide an attractive, maintenance-free and cost-effective roof. The range includes eaves and ridge ventilation systems, including terminals and weathertight ventilation paths; a capped dry hip system and a mitred hip system which achieves a neat detail without the need to use lead.

Dry verge systems and dry-fixed valleys are also available.

On the waterfront

The Waterfront, a complex of 24 two-bedroom flats in Leicester designed by J S + P Architecture, has a dramatic setting on the banks of the Grand Union Canal. Formerly a brownfield site and part of the Leicester City Challenge area, the new five-storey block is next to the Pex Building, a listed building that has recently been refurbished, and faces Castle Gardens on the other side of the canal.

To reflect the rich industrial heritage of this part of the city, the architect has used reddish/brown brickwork for the walls and has covered the series of interlocking pitched roofs with Cambrian Slates. 'We were keen to use traditional materials on this building and Cambrian Slates met both the aesthetic brief and the budget, ' said Jonathan Smith of J S + P Architecture.

The practice referred to the DesignMaster service for assistance with the roof detailing - DryVent ridges and RedVent eaves vents were used throughout. It used SpecMaster, Lafarge Roofing's specification service, which gives a 15-year design liability guarantee.

KAMI SYSTEM

Kami, a lightweight roofing system, was launched as a new addition to the product range at last year's Interbuild. It has been produced in Sweden for more than 25 years, by a company recently acquired by Lafarge Roofing. The product is still made in Sweden but it now has the backing of Lafarge Roofing's technical support and estimating services.

Kami is a tile-formed steel sheet, giving the appearance of a tiled, pitched roof but with the benefits of steel - lightness and ease of installation. The steel sheets, 0.45-0.9mm thick and manufactured in lengths of up to 7m, are pressed into tile forms - a process of pressing and profiling which also gives the sheet rigidity and increases its bearing capacity so that it can bear the weight of people walking on the roof.

Before pressing, the steel is galvanised, primed and prepainted on the underside with an epoxy coat. After pressing, the top surface of the sheet is coated. A number of different sanded or smooth coating systems are available; Terra coating - a four-layer paint system incorporating quartz sand granules; KCC a three-layer paint system; plus polyester and Plastisol coatings.

Kami is available in several rolled or pantile-shaped profiles, with a range of thicknesses, surface finishes and up to eight colours.Details and fittings for eaves, ridge and verge are available; examples of detailing can be found on the Lafarge Roofing website in the DesignMaster section.

Like other metal-based roofs, Kami is fixed to battens or purlins and laid on steel or timber-frame roof structures. But its tile format gives it particular advantages for use in housing, because:

it is fast to erect, and suitable for prefabricated housing systems;

in local-authority and housing-association refurbishment schemes, the Kami roof is a fast and economical method of replacing a faulty flat roof with a low-maintenance pitched roof; and lit is ideal for new-build housing, schools and hospitals where vandalism is a problem.

Kami is guaranteed for up to 30 years and has BBA certification.

LANDMARK SERIES

The Landmark series of concrete tiles and slates offers an extremely durable and colour-consistent alternative to some traditional roof coverings in the UK. Launched in 1999, the range includes three versions of pantiles - rich terracotta, terracotta brindle and brown brindle - which closely follow the appearance of vernacular roofs on domestic houses in Suffolk, Norfolk, Essex and Humberside. There are also two slates, Brecon Grey and Snowdon Grey; each has a blend of natural hues which matches the appearance of traditional slates.

Like the original roofing materials, the rich colours of Landmark tiles and slates have subtle variations of tone. They are produced by means of a new technology known as ColourFusion. The basic tile body is of pigmented concrete. A dense layer of acid-rain-resistant and frost-resistant pigmented amalgam is fused to the upper surface of the tile body; the surface is then coated with two clear protective UV-resistant layers of polymer. The result is a tile that will maintain its appearance and colour-fastness for at least 25 years. The smooth surface also controls the growth of algae.

Landmark tiles and slates are available with matching ridge tiles, hip tiles, dry ridges and verge systems, and a complete range of matching fittings and accessories.

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