Housebuilder sustainability comment
“When it comes to the house building sector, sustainability isn’t just about reducing construction waste and carbon levels, it is also about making efficient use of materials and labour to build quality homes in a cost effective and sustainable way. This is one of the reasons that offsite construction methods are gaining momentum.
“Not only are timber frame and modular assembly seen as a way of reducing the environmental impact of building new homes, one of the main reasons for their growing popularity is that housebuilders are looking for more efficient construction techniques that are less dependent on skilled labour, in order to produce the high volumes of properties that are needed to tackle the national housing shortage.”
Indeed, Barratt Homes recently said it will increase the use of offsite manufacturing and timber frames across its business and plans to use timber frame on over 1300 plots during 2017.
This increasing focus on offsite building techniques means housebuilders need to consider lightweight and sustainable materials for the building envelope, as Gavin White continues:
“When looking at advanced methods of construction, the weight of roof coverings and facades becomes very important. For example, the big advantage of using a timber frame constructed offsite means that not only can it be erected very quickly on site, but because it is lightweight, the house is much cheaper to build. The less material used in the building, then the lighter the overall weight and the less foundations required to support the structure, resulting in significant cost and efficiency savings on the overall build.
“If housebuilders want to use a lightweight timber frame, then they need to use a lightweight roof covering and fibre cement is a very good option because, as well as being 100% recyclable, it gives the contemporary slate aesthetic that is very popular in new housing at a much lower weight, while still being very cost effective. In fact our fibre cement slates only weigh around 20.4kg/m2, which is less than half the weight of our thin leading edge concrete tile.
“Fibre cement slates can also be installed much more quickly than natural slate, whether on site or in a factory as part of modular construction. The fact that fibre cement slates have just one very robust fixing method means they have an advantage over many other roofing products, as housebuilders don’t need to worry about a fixing specification and they are ideal for use in areas with high exposure.
“When it comes to the walls, using a fibre cement slate facade, like our Vertigo system, can have significant weight savings over brick and block. Using a block and timber frame with Vertigo offers a lightweight facade of just 283 kg/m2, compared to a weight of 334kg/m² for traditional brick and block - over 15% lighter.”
Fibre cement slates – environmental benefits
Fibre cement slates are also growing in popularity on traditional ‘bricks and mortar’ new builds because of their aesthetic and environmental credentials.
Using Marley Eternit’s fibre cement slates on the roof, or as cladding, can help housebuilders to achieve environmental credits under the Home Quality Mark scheme because they have an A+ rating in the BRE Green Guide, Environmental Product Declaration to BS EN 15804 and BES 6001 Responsible Sourcing accreditation. So housebuilders that specify them will get extra points for using responsibly sourced building materials and those that have the lowest environmental impact.
Fibre cement slate is also fully recyclable, making it a popular choice for new housing developments with strong sustainability objectives and a focus on end of life use.
One example of this is the UK’s first ‘Eco Town’ in Bicester, which has used timber frame construction, together with Marley Eternit’s Rivendale fibre cement slates, to create the first zero carbon community.
North West Bicester (NW Bicester) is a ground breaking project led by A2Dominion to create the first eco town in the UK, with the long term visions of providing up to 6,000 sustainable new homes.
The first phase at Elmsbrook used cutting-edge technology and sustainable building materials, including Marley Eternit Rivendale fibre cement slates, to create 91 true zero carbon homes that are also future-proofed against climate change.
The Eco homes provide the tools and technology for communities to be able to live in a more sustainable way and this philosophy also applies to their construction. The new homes are made from environmentally-friendly timber frames, using sustainable materials to reflect the local building style.
When it came to specifying the roofing materials, Marley Eternit Rivendale fibre cement slates were chosen as part of a package of sustainable building materials to help meet embodied carbon targets in a cost effective way. Around 50,000 slates were used on the first phase of housing.
The highest performing eco-design and eco-build materials were selected for the houses on site to make it easy for residents to lead a sustainable lifestyle. As well as reducing the operational carbon of the homes, the embodied carbon and weight of the building materials was also considered. However, as the homes need to be affordable, cost effectiveness was also very important.
In fact, cost was the main driver for using fibre cement rather than natural slate. Rivendale slates were selected because they give the aesthetics of natural slate but were commercially viable and crucially, they are lightweight and have good embodied carbon credentials.
In total the Elmsbrook development will see the construction of 393 true zero carbon homes in four phases, as part of an ambitious plan to build up to 6,000 highly efficient homes in NW Bicester over the next 25-30 years.
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