In this week's roofing special, metal cladding in a variety of colours, rooflights in a variety of shapes and fixings that are, well, invisible. Plus, an ancient hill fort provides inspiration for this unusual church roof
What's the spec? St Bernard's Church, Glengormley, Belfast

The parish of Glengormley in Belfast has seen its fair share of the Troubles in recent years. This brand new church replaces an earlier structure that was only 13 years old when it was destroyed in an arson attack in 2001. The only conditions the client stipulated for its replacement were that the church walls should be built from stone and the roof from slate. The designer, Dempsey Architects, otherwise had a free hand, and it turned to Irish history for ideas. The unusual shape that is chose was inspired by an ancient type of Irish hill fort used as a place to retreat to in times of danger – hence the embracing wall at the side that protects the church.

The circular, offset roof proved a challenge for the contractor, as it is the first time slate has been used to cover a roof of this shape in the UK. Six different sizes of rhomboid-shaped tiles were needed to achieve the correct lap around the building's circumference. The rest of the roof structure is fairly conventional, although much harder to construct due to the shape. The tiles are supported on battens, under which a breather membrane has been fitted. This is supported in turn by counterbattens and rafters. Insulation boards are fitted under the rafters with the whole roof structure supported by steel.

Inside, the roof is clad with oak planking. The horseshoe-shaped clerestory glazing encircling the roof provides most of the light for the interior and the angled cupola at the peak of the roof directs light over the sanctuary to provide an appropriate focus within the church for the congregation.

Project team
Client Very Reverend Father Daniel Whyte
Architect Dempsey Architects
Structural engineer Albert Fry Associates
M&E Delap & Waller Consulting Engineers
QS Naylor & Devlin
Contractor O'Hanlon Brothers Construction
Roofing contractor A&M Doris

Flat roof single-ply membrane
Sarnafil 301

Eternit 302

Breather membrane
DuPont Tyvek 303

Clerestory windows
Schüco 304

Insulation board
Dow has introduced a roof insulation system called Roofmate that is made from its Styrofoam extruded polystyrene insulating board. There are two variants: the RL-X system, which is an interlocking tongue-and-groove board for laying over rafters, and RL-BE-X, a square-edged board for fitting between rafters. Dow says the board has low water absorption and high compressive strength. The RL-X boards measure 2500 mm long, 600 mm wide and 60 mm thick. The RL-BE-X is 2500 mm long, 550 mm wide and 90 mm thick. The products comply with Part L of the Building Regulations.
Dow 305

Metal roofing profiles
Eternit Building Materials has moved into the metal roofing and cladding market with the formation of a metal profiles division. The division is kicking off with the launch of three profiles suitable for roofs, walls and lining. The sheets have a cover width of 1 m and the outer profiles are available in thicknesses of 0.5 and 0.7 mm. A range of flashings and fixings is also available. The sheets are galvanized to protect them from corrosion and are available in 27 colours in a plastisol finish or as a polyester coating in a more limited colour range. The company has also added a natural slate to its Navia range. Navia 23 is a traditional grey colour and is aimed at the market in the North-east. It is between 5 and 6 mm thick and measures 400 × 250 mm or 500 × 250 mm.
Eternit Building Materials 306

Asphalt sealant
Coverall has made its water-based, cold-applied asphalt sealer available in seven-litre pails in addition to the existing 15-litre size. The product is intended for sealing paths, drives and flat, felt and corrugated iron roofs. The company says it can be applied by unskilled labour and has a coverage rate of 6-7 m2 from the new pail. It is available in grey, black, red or green.
Coverall 307

Play School-shaped rooflights
A range of polycarbonate rooflights called Ventalux has been launched by rooflight maker McKenzie Martin. Rectangular, square and round versions are available and are all mounted on white PVCu upstands. The domes are available in clear, opal and coloured finishes in single, double or triple-skin variants and in a range of sizes. Options include insect screens and integral sunshade blinds supplied preassembled. Security rooflights are also available.
McKenzie Martin 308

Aluminium roofing gets Brum deal
Metal cladding systems maker Ash & Lacy has supplied 500 m2 of its Ashzip 400 aluminium standing-seam roofing for a social housing project in Birmingham. The company also provided the components to create the whole roof package including its Ashfab flashing system, Ashfix fasteners and Ashzip halters to fix the roofing sheet to the purlins. The roof is a monopitch design and covers a three-storey block on the Benmore Estate. The work was carried out for the Optima Community Association.
Ash & Lacy Building Systems 309

Primary school sees the light
Rooflight maker Brett Martin Daylight Systems panel glazing system was used to replace single-skin Georgian wired glass lights at Linton Mead Primary School in Thamesmead, London. The product used was the Xlok Express, which uses 16 mm thick structural polycarbonate with a U-value of 2.0 W/m2K, fitted into a white powder-coated aluminium frame. It was installed over the mansard roof areas of the main hall, staff room, classrooms, kitchens and corridors. The company's Mardome Premier rooflights were installed on the flat roof over the toilets.
Brett Martin Daylight Systems 310

Flyweight roofing felt
Geotextile specialist Terram has launched what it describes as a new type of roofing felt, called Roofstat 110. The company says it weighs 110 g/m2, the same as medium-weight paper and one-third of the weight of normal roofing felt. It is made from polypropylene and polyethylene and is supplied in 1.5 m wide rolls. Terram says the product is rotproof, has full BRE certification, and has a good resistance to nail-tear and fire, and good tensile strength.
Terram 311

Roofing fasteners in many colours
Fastener specialist SFS Intec has brought out its irius-type fastener in colours to match the Corus Celestia range of metallic colours used on its metal roofing and cladding products. The irius fastener has a special type of head designed to be less obtrusive than other fasteners and is intended for quick and easy installation. The fasteners are made from austenitic stainless steel.
SFS Intec 312

Invisible fixing system
Single-ply roofing maker FDT has developed a fixing system that eliminates visible screw fixings from beneath the roof deck. It is intended for clients who want to dispense with a suspended ceiling system. The system works by attaching the company's Rhepanol FK membrane to Velcro strips, or glueing its Rhenofol CV membrane to PVCu strips. The strips are fixed to the top of the roof deck at 850 mm centres. The system uses a specially designed profiled roof deck.
FDT 313

Information point

Span tables revised
Trada Technology has published Span Tables for Solid Timber Members for Floors, Ceilings and Roofs (Excluding Trussed Rafter Roofs) for Dwelling. The tables have been revised in line with current British Standards and design codes and are used for selecting the correct size for timber members for floors, ceilings and roofs. The tables are aimed at architects, surveyors and building control officers, and the information from the tables can be submitted as part of an application to building control for Building Regulations approval.
Trada Technology 314

The future’s green
BRE has brought out a publication based on DTI research called Digest 486: Reducing the Effects of Climate Change by Roof Design. The research concluded that green roofs – vegetated roof covers with growing media and plants taking the place of tiles – are best able to cope with the effects of climate change, including higher wind speeds, increased rainfall and longer, hotter summers. This is because green roofs protect the waterproofing membrane from exposure to ultraviolet light and weather extremes. They also cope well with wind and release water slowly after heavy rainfall, thus reducing the risk of flooding. Large numbers of green roofs in urban areas can also improve air and water-runoff quality. The digest says that government subsidy may be needed to encourage the uptake of green roofs in urban areas, as the initial construction costs are higher than other roof types.
BRE 315

Euroclad publishes report
Roofing and cladding systems-maker Euroclad has launched two publications. The first is based on research carried out by cost consultant Davis Langdon into the cost benefits of non-combustible sandwich panels and built-up roofing systems. Called The DLE Report, it was commissioned to clear up what the company says is a misconception that these types of system are more expensive to install than combustible, polyisocyanurate (PIR) foam-cored sandwich panels. The publication says that mineral wool-cored products are, on average, 20% cheaper than the PIR-cored products. The second publication describes the company’s 25-year Elite Warranty Scheme. This brings together several manufacturers including Rockwool, Knauf and Brett Martin Daylight Systems under the name of the Elite Alliance. Euroclad guarantees all these products when used as part of a complete system including its own roofing and cladding systems.
Euroclad 316

FalZinc queries answered
Metal group Corus has brought out a 12-page brochure on its FalZinc-branded range of roofing and facade systems. The aluminium product features a pre-weathered zinc layer for aesthetic and practical reasons; the company says the product is highly durable and corrosion resistant, even in marine environments. The brochure describes the benefits of the system including suitable applications, and addresses common specifier questions about FalZinc.
FalZinc 317

Wind load assistance
The Steel Construction Institute has published the P286 Guide to Evaluating Design Wind Loads to BS 6399-2 1997. It offers guidance on the use of the British Standard design procedure of that name. This includes advice on calculating the wind load on buildings. The SCI has also launched a CD-ROM that qualifies for Continuing Professional Development points on BS 6399 –2 1997.
Steel Construction Institute 318