This month's roofing special takes in flights of fancy at Farnborough Airport, rounds up the latest products and lays down the facts about syphonic drainage systems
Dry-fix roof ventilation
A dry-fix ventilation system has been introduced by Lafarge Roofing Systems, formerly known as Redland Roofing Systems. The Rapid Vented Ridge and Rapid Hip systems include the Metalroll ventilation protection roll, which Lafarge says makes it easier to achieve a weatherproof fit.

Lafarge claims that in trials the Rapid Hip and Rapid Vented Ridge systems were installed 33% faster than equivalent systems using wet mortar.

To mark the change of company name, Lafarge has relaunched its roofing website. From April the site will include a CAD library of 5000 high-quality roof drawings that have all been updated to comply with the latest Building Regulations, including Part L. The site also features ViewMaster, which allows specifiers to experiment online with various coloured roof tiles. The Redland name has not entirely disappeared – it is now the brand name for Lafarge Roofing's UK product range.
Lafarge Roofing Systems 901

Thermal and acoustic insulation
Knauf Insulation has expanded its range of products: Crown Wool, the glass mineral wool used in the thermal and acoustic insulation of pitched roofs, is now available in 170 mm thickness; and Crown Factoryclad, the glass mineral wool insulation for profiled metal-clad buildings, is being offered in thicknesses of up to 200 mm. The company has also launched Crown Factoryclad Plus, which is designed for twin-skinned built-up roofing systems where high thermal performance is required without an increase in thickness. Knauf Insulation has CE-marked its entire range of glass and rock mineral wool products to comply with the Construction Products Directive 89/106/EEC.
Knauf Insulation 902

The Kingzip guide
Kingspan Insulated Panels has introduced a 20-page guide for Kingzip, its new pre-engineered roofing system. Construction details for verges, eaves, hips, valley gutters, barrel vaults and rooflights are included in the guide, and each can be downloaded from the Kingspan website.
Kinspan Panels 903

Zippy standing-seam roofing
SpeedDeck Building Systems has launched SpeedZip, a mechanically zipped standing-seam roofing system. The galvanized-steel system can be manufactured on site using a mobile production unit or in the factory, in lengths of up to 40 m. SpeedZip can be used for convex, concave and waveform shaped roofs and can be supported by SpeedDeck's range of structural decks. Reinforced Plastic (GRP) rooflights are also available from SpeedDeck for straight, convex and concave roofs.
SpeedDeck Building Systems 904

Doubly dense insulation boards
Rockwool has introduced Hardrock Dual Density insulation boards for flat roofing systems. Hardrock DD satisfies the requirements of the new thermal and fire Building Regulations. It also has a high-density top surface, which makes the boards very resistant to compressive loads, according to the company.
Rockwool 905

Tile-effect panels on visitor centre
Ward has supplied its pre-engineered, pre-insulated metal roof tile system to the new agricultural visitor's centre in Otley, Suffolk. Ward says the original roof timbers were unable to support the weight of traditional roof tiles which is why the client opted for the lightweight insulated tile-effect panels. The roof tile's single-fix installation fits directly onto purlins, eliminating the need for battens, roof felt and separate insulation materials, says Ward, and mimics the look of natural clay pantiles.
Ward Building Components 912

Flame-free bitumen application
Icopal has developed a flameless method of applying its FireSmart torch-on bitumen roofing system. The FireSmart Application gun uses turbine technology to create temperatures of between 800 and 1000°C without generating a naked flame. There are two application systems available: the hand-held supporter unit (for detail work) and the automatic side lap welder (for welding laps). FireSmart is a roofing system using Pyrozenic bitumen, which is formulated from volcanic silicone rock. This enables the system to withstand very high temperatures and exceed the fire standards in both Europe and the UK.
Icopal 913

Antiquated roof tiles
Sandtoft Roof Tiles has launched the Arcadia, a new clay pantile that is designed to emulate the character of an aged or reclaimed English clay pantile. Sandtoft says the manufacturing process results in a random finish, which creates a weathered look. The tiles are 17.5 mm thick and come with a 60-year guarantee.
Sandtoft 914

Copper roofing expertise online
Copper in Architecture has expanded its website to include all the detail drawings from its new technical roofing and cladding guide, Copper Roofing – In Detail. It also includes: CPD material on copper in general; animation of the patination process; coverage of topics such as environmental implications and comparative costings; numerous projects and a link to other European copper site project pages. The 120-page technical guide includes the latest techniques from Europe including the long strip method, and machine seaming on site. It is available for £25 from the Copper Development Association.
Copper In Architecture 915

PVC cover for Oxford bookstore
The Blackwell bookstore in Oxford has just been fitted with a new single-ply PVC roof membrane from Alkor Drakka. A new metal deck was fitted onto existing steels and then covered with an Alkorplus vapour control layer, a 60 mm rigid CFC-free insulation board and finally an Alkorplan F 35170 single-ply waterproofing membrane. Membrane joints, roof penetrations, edge, corner and parapet details were sealed using a combination of Alkorplus 81025 solvent fluid, hot-air welding and other accessories from Alkor Drakka.
Alkor Drakka 916

Celtic-style slates
Alfred McAlpine Slate has extended its range of natural roofing slates with the launch of the Celtic tile. The slates have naturally occurring markings that give it a textured finish, according to Alfred McAlpine. The Celtic tiles are available in blue–grey or dark blue–grey and come in a range of sizes.
Alfred McAlpine Slate 917

Curved planes at Farnborough Airport

Kalzip aluminium standing seam roofs have been specified for aircraft hangers at Farnborough Airport. The curved roofs of the three hangar building bays each span 93 m, and each bay is tied under the floor plane, which allowed Reid Architecture to remove the bottom member of the roof structure. This reduced the weight of the structure and minimised the building volume, clad area and wind loading. The hangers used more than 13,500 m2 of curved and pre-curved Kalzip 400 mm profile.
Kalzip 900

What’s the spec?

Air traffic control tower, Farnborough Airport
The specification of the aluminium roof for the new air traffic control tower at Farnborough Airport was as complex as the twisting curved geometry suggests. Reid Architecture had to find an affordable system that could clad the fluted 35 m high control tower and the wing-shaped structure at its base. Reid approached a number of cladding and roofing suppliers but their solutions were either over-budget or over-complicated. At one point a boat-building yard was approached to help develop a seamless skin, but its prices proved too high. The solution chosen by Reid was developed in conjunction with German-based Mero, which specialises in Space frames and shingle construction. A diamond shaped pattern was created with aluminium shingles, which the architect says resembles a tightly stretched metallic snakeskin. The shingles connect to a more traditional curved Kalzip roof on the base building. The roof structure of the control tower is supported by four simple columns positioned at the rear and cantilevered at the front to minimise obstructions.
Project team
Architect: Reid Architecture
Main contractor: Bovis Lend Lease
Structural, M&E and facade engineer: Buro Happold
Quantity surveyor: Davis Langdon & Everest

Roll-moulding system for complex roofing

Roll-moulding system for complex roofing Bemo Systems has launched a roll-moulding system that the firm says is capable of manufacturing complex metal roof sections. The Monroe System can process aluminium, steel, stainless steel, zinc and copper on site or in the factory. Bemo can create metal sections of any length and thicknesses of between 0.7 and 1.2 mm. The system was first used on the roofing at Charlotte Airport in South Carolina and is now being used on a 26,000 m2 sports arena in Budapest (above). Although every aluminium section at the sports centre is of a different shape, Bemo says the sheets – up to 55 m in length – are being fitted on site in only four months.
Bemo Systems 910

Guttering for large commercial schemes

Marley Plumbing and Drainage has introduced a gutter specifically for large commercial roofs. The aluminium Giant is a 200 mm x 150 mm trapezoidal profile with external union pipe joints and concealed supports. It is sealed with Alutec sealant and is used in conjunction with Marley’s Alutec Aligator jointing method, which requires no bolts. The Giant is designed to deal with capacities of more than 10 litres per second and Marley says that its wide top edge means it is ideal for steep roofs or valleys where run-off can overshoot standard gutters.
Marley Plumbing and Drainage 911

Renovation matches Scottish slates

Eternit has supplied its NA8 slate tiles for a self-build renovation project in Helensborough, Scotland. The slates had a similar colour, weight and texture to the Scottish slate tiles that had to be replaced. Eternit says that NA8 is specifically produced for the Scottish roofing market.
Eternit 918

It sucks: Poor specification on siphonic drainage

CRM Rainwater Drainage’s Malcolm Wearing offers expert advice on what to look for when considering siphonic roof drainage systems In the 1980s and 1990s, siphonic roof drainage revolutionised the way large roofs were drained, but poor specification and some inadequate contractors in the early days have damaged its reputation. Siphonic roof drainage uses the building height to horizontally suck water along the building in highwater pipes, reducing the number of downpipes required. There are several details to consider when specifying siphonic systems, such as whether or not the roof is suitable. It’s a common misconception that siphonic systems can be used anywhere – these systems are actually more susceptible to blockage than most, so it’s not advisable to use them in areas where access is restricted. They can also be noisy to operate, and so great care must be taken when specifying in residential buildings. Many of the previous failures were a result of inadequate levels of protection against severe rainfall. In fact, many buildings with existing siphonic systems have problems and will need upgrading. It is essential that the rainfall level is set to protect the building for its lifespan. For most buildings, a minimum protection life of 90 years should be used, which can be converted into rainfall levels using BS EN 12056-3:2000. What type of pipework? Most of the UK installations are formed in high-density PolyEthylene, a cost-effective and robust material. This should comply with DIN19535, be capable of withstanding the design pressures, and provision made for thermal expansion. It is unlikely that the specifier will be able to check the design of a siphonic system. However, as all systems work in the same way, it’s possible for an expert to check functionality. Properly specified, siphonic drainage can be the best approach for many buildings, but a competitive market means that corners are sometimes cut. It is therefore worth seeking independent expert advice. For more details, see