Wed 1 Aug 2007
A versa-tile approach
With the growing demand for eco-friendly roofing coming up against the need for designs to conform to the local vernacular, housebuilders will now have to be a lot smarter when it comes to choosing their roofs. Natalia Gameson looks at what's ahead for the industry.It goes without saying that roofing of the future is likely to get a great deal more complex than it is today. Thanks in part to incessant drives for sustainability and the housebuilder's penchant for shoving extra rooms into roof space, times are a changing.
"Everyone is currently building with standard roof trusses, but now housebuilders need to see roofing as part of a bigger picture as the subject grows in complexity. The industry has already changed its ways of working in using different types of roof trusses with steeper pitches to allow for a room or two to be incorporated into the roof, which obviously requires the use of more tiles to kit out a bigger surface area. This tends to incur a 20 per cent increase in roof construction costs, but obviously rewards the housebuilder handsomely for this outlay, as extra rooms tend to add thousands onto a home's overall value. Sustainability may change all this even further, as renewable products need to fit into the overall package - photovoltaic panels, for example, need to do the same job as a roof tile to ensure water doesn't leak through," says Dave Mitchell, the HBF's technical director.
So, with sustainability set to change the way the industry builds forever and so much to take into consideration, what are the best products available to prepare for the changes that lie ahead?
Green roofs
Installing 'green living' roofs is an excellent way to raise the profile of a new development, as well as a good opportunity to bag more EcoHomes points. Linden Homes' Market Quarter development in Chippenham, Wiltshire, a scheme of 256 one- and two-bedroom apartments and three- and four-bedroom houses, features a multiplicity of such roofing designs. Kitted out with a special drainage layer, which is fitted over the waterproof membrane, the roofs are covered with soil and seeded with grass and plants. The thirsty flora and fauna above also provide a clever solution to excessive rainfall, as they greedily soak up excess rainwater, working to prevent drains from overflowing and creating a safe and pleasant habitat for flowers, butterflies and birds, in one fell swoop.
Working on a similar project, engineered timber specialist Palgrave Brown has recently won a contract to provide roof trusses, TJI beams and staircases at The Hamptons, a 60-acre development of 480 new homes from the St James Group in Worcester Park, Surrey. This sustainable mixed-use scheme, a reworking of the areas's former sewage treatment works, features 30 acres of grassland and wildlife habitats.
Offering PEFC (Programme for the Endorsement of Forest Certification Schemes) and Forest Stewardship Council (FSC) certification on its products, supplied in line with government requirements for EcoHomes ratings, Palgrave Brown prides itself on possessing strong environmental and sustainable policies. The company will be kitting out 133 of the scheme's townhouses and apartments with Mansard roofs, popularised by Francois Mansart, whose designs can be found in second Empire and Romanesque architecture, and featured two slopes, the lower almost vertical to allow extra roof space for extra attic rooms, while the lower roof can feature a straight, convex or concave shape.
On a space-making front, the firm states that prefabricated timber-trussed solutions are second to none in creating suitable roof living areas on site to make the build process more profitable and efficient for all concerned.
Similarly, Smartroof uses PEFC accredited sustainable timber, and boasts a construction time of a mere five hours for a pair of its roofing units. Suitable for townhouses and terraced units, the Smartroof system uses modular interlocking panels to speed up and simplify construction on site. Here, the roofs span from gable to gable to allow for total flexibility in the positioning of roof lights and dormer windows, offering what the firm terms "100 per cent roof space utilisation".
For schemes where a traditional look may be more fitting, old timer tiles are certainly an established standard on roofs throughout the industry. Imerys has recently launched a 20-centimetre by 30-centimetre tile that is manufactured in Beauvais, France, to the latest environmental standards, including EN14001 - all the firm's tiles meet the requirements of BS EN 1304 (1997) and come with a 30-year guarantee of durability.
Using 43.5 tiles to cover a square metre in this larger, more economical format, will save the housebuilder money, while fewer battens will be required when fitting the tiles, thus both speeding up and easing the work on high, particularly on larger roofs. Designed to resemble a conventional double camber product, the tile's flat underside prevents any movement or 'chatter' in windy periods, while the product's anti-capillary channels work to enhance the overall performance of a traditionally pitched roof. The tiles are available in a variety of traditional shades, hues and textures.
Returning to the question of dispensing with gallons of unwanted rainwater, Alumasc's new range of 100 per cent recyclable pre-finished heritage cast iron rainwater solutions offer durability, rigidity, noise suppression, longevity and aesthetic appeal. Suitable for all projects, ranging from refits in listed and heritage buildings where planning may not allow anything other than cast iron products to be deployed on site, to modern housing, the range features half-round ogees, beaded half-round and molded gutters and round, square or rectangular downpipes with original socketed joints.
Solar roofing
Installing photovoltaic panels may be equally useful in the fight to win more precious EcoHomes points. Recommended by the NHBC in its guide to renewable energy, solar thermal systems are used to heat domestic hot water supplies, while solar electric cells will actually generate electricity. Panels should be fitted on unobstructed roofs, ideally facing south, south-east or south-west - installing the units on north-facing roofs is not a good idea, nor is locating the panels underneath trees or chimneys, as these will reduce the amount of energy collected.
Ferroli offers a solar combi system that aims to provide homeowners with a complete solar hot water package. The combi unit utilises a drain-back system that allows the 'solar collector' to empty during periods of no demand, freezing temperatures or possible solar overheat. Heating water in an AquaSol cylinder, the liquid then flows through a Ferroli Optimax HE combi unit, which can top up the supply if the temperature is not sufficient. Ferroli also produces a system for larger households, where the solar collector panels will pre heat the water stored in an AquaCyl twin-coil cylinder by a heating coil; the firm's high-efficiency boiler then tops up the water temperature via a secondary coil in the cylinder.
Lafarge Roofing is one of the UK's biggest manufacturers of photovoltaic systems for housing, and it was the first to provide a means of integrating panels within the traditional slates and tiles beloved by housebuilders and homeowners nationwide. Lafarge also recently supplied panels to eco-builders Eden Frame for a project in Cliburn, Cumbria. Working with the properties' other energy-saving features, the panels helped the houses, which didn't feature a single radiator, to sell off-plan before leaving the architect's drawing board. The first family to live in one of the Cliburn houses says Lafarge's roofing system has generated more than half their total electricity needs during a year of living in their new home.
Imerys also offers an integrated photovoltaic roofing system, made up of solar energy panels and clay roof tiles, which has been approved by the European commission, so check out their website for more information.
Insulation
As approximately 35 per cent of a home's insulation is lost through its roof, today's new houses need to be built with ways in mind of improving this sorry statistic. "Making a home thermally efficient has traditionally taken second place to keeping out the rain," says Neil Conway, Vencel Resil's sales manager. "But things changed with the launch of expanded polystyrene (EPS) in the 1950s. Being 98 per cent air and two per cent solid material, it's surprisingly rigid and 100 per cent recyclable."
The firm has recently launched Jabroof SlimFix, a sandwich construction partnership of eight-millimetre thick, moisture-resistant chipboard that is bonded to an insulating core of EPS. This aims to combine the best of both worlds, the insulative properties of EPS with the strength of the chipboard. First used in Europe in 1972, it's now become a popular form of roof installation, paving the way as it does for smooth and well-insulated loft-bedroom construction up on the roof - as insulation is provided at the level of the rafters, the roof space remains warm and snug.
Similarly, DuPont Climate Systems' insulation materials offer users energy saving of up to 15 per cent per annum. Composed of Tyvek Enercor metal breather membranes for roofs and walls and DuPont AirGuard, a reflective vapour control layer, the materials are designed to work with traditional insulation products to create an air-tight building envelope to provide good protection against external and internal thermal heat loss.
Back to battens and basics
No matter how sustainable a product may claim to be, if it isn't properly reinforced with reliable products, it's hardly worth installing - entire roofs can be stripped by a health and safety inspector if they are not fitted to required standards. John Brash's timber JB-RED batten range comply with regulation BS5534 and working in line with the firm's computer-based system, can pre-grade roofing battens at their point of production. Analysing each batten at a rate of over 250 metres per minute, the slope of grain and rate of growth are also checked for defects. These battens do come with a slightly inflated price tag, indicative the firm says of the costs incurred while working on this £2 million development process with the Building Research Establishment (BRE), but all products, which are PEFC and FSC accredited are guaranteed to pass a building control or quality inspection process.
Similarly, Forticrete's tiles, which feature a thinner, more streamlined, front leading design, have been recently ranked second in David Wilson Homes' chain of suppliers. Awarding the firm an overall score of 93 per cent, this follows a previous award given by the housebuilder to the company for most improved environmental performance in February 2005. "Wilson Bowden's league table is taken very serious in the industry," says Shaun Gray, Forticrete's managing director. "It's no small achievement to have risen so high in such a short space of time."
Forticrete's range features Minislate, Centurion, Senator and Gemini designs, which have recently been reworked to give better texture, colour and strength to the patterns.
First published in Show House Magazine August 2007.
The greatest care has been taken to ensure accuracy but some information contained within this article may have changed since it was first published.
Posted by Natalia Gameson
in Alumasc, DuPont, Features, Ferroli, Forticrete, Imerys Rooftiles, John Brash and Company, Lafarge Roofing, National House Building Council (NHBC), Palgrave Brown, Smartroof, Vencel Resil on Wed 1 Aug 2007
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