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Cannabis Campaigners' Guide News Database result:
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UK: Home is where the hemp is
Christine Webb The Telegraph
Monday 16 May 2005 It seems the unlikliest building material, but even Terry Waite has=20 championed the use of cannabis's respectable cousin, says Christine Webb A new crop of homes is being sown in East Anglia. Or at least, seedlings=20 planted this spring will mature in four months, and may be used to make=20 building blocks for houses. The plants in question are cannabis hemp,=20 which, when mixed with lime, has special "green" properties that could take= =20 the building industry by storm. Before you ask, there are no narcotic influences behind this idea. This=20 form of hemp is a distant cousin of the recreational drug, and lacks its=20 best-known properties. It is a strong, fast-growing plant and has a tough=20 core that can be incorporated with lime to make a malleable mess; this can= =20 be slopped between two sheets of plywood shuttering to form a low wall.=20 Once filled, the shuttering is moved up a notch, and the process repeated=20 to build up the wall's height. One of the pioneers of this innovation is no less than Terry Waite, the=20 adviser to the former Archbishop of Canterbury Robert Runcie, who used the= =20 material for a renovation project at his Suffolk home. The method was first= =20 used in this country in 1996 to renovate a guest cottage in the grounds of= =20 Waite's home. His architect, Ralph Carpenter, had just returned from=20 France, where he had seen hemp being used to build new houses. "Some of the beams in our house date back to 1320, and at the bottom of our= =20 short garden was a dilapidated, timber-framed building used as an animal=20 shelter. We decided to renovate it and make it somewhere for our=20 grandchildren to stay," says Waite, the author of several books, who works= =20 for charities including Victim Support and Hostage UK. "Ralph suggested the material because it would easily fill in between the=20 existing timber frame, so that you still had the beauty of the wood on=20 display, and it would provide insulation, so that the building would be=20 warm in winter, cool in summer. "Large sacks of this chopped hemp arrived, and our builder mixed it with=20 lime in a cement mixer, then poured the slurry between two sheets of=20 shuttering to form a wall. It took a long time to dry out, but it set=20 extremely well to a pleasant honey colour, and we've had no trouble with=20 it. It's not too smooth a finish, so it suits this building. It's made a=20 nice little one-up, one-down guest-house. Somehow it's got a friendly=20 feeling, and in winter a wood-burning stove makes it cosy. We've named it=20 Ella's House, after my small grand-daughter." Ralph Carpenter, of Modece Architects (01284 761141 ), later used the=20 technique to build an extension for his own 17th-century home, near=20 Sudbury. He was so happy with this that he also convinced the Suffolk=20 Housing Society (www.suffolkhousing.org) and St Edmundsbury Council to run= =20 a trial by building England's first two new homes from hemp, at an=20 affordable housing site in Haverhill. These stand beside ordinary=20 block-built houses, giving a direct comparison for members of the Building= =20 Research Establishment (BRE), who have a grant from the Department for=20 Environment, Food and Rural Affairs, to explore hemp. Thermographic images from the BRE illustrate the superior insulation=20 properties of hemp, and the houses' structure and durability were reckoned= =20 to be at least equal to those of conventionally constructed homes. The=20 hemp-and-lime mix "breathes", so less condensation collects; it is pretty=20 fireproof and the hemp homes won hands down on environmental impact, being= =20 renewable and recyclable. That would be enough to attract small builders. But what could really throw= =20 such a material into the premiere league is its potential to produce a=20 carbon neutral - or even a carbon negative - building method, which would=20 more than come into its own if, as rumoured, carbon rationing is introduced= =20 by the EU to combat global warming. "There have been no significant problems with the hemp houses we built=20 nearly four years ago," says Steve Clark, of the Suffolk Housing Society.=20 "That was the first time hemp had been used to build new houses in this=20 country, but if we were going to use hemp on any larger scale, we'd need to= =20 introduce economies into the building process because it's very=20 labour-intensive. So we're exploring the idea of making the hemp mix into=20 standard-sized building blocks." Building with lime-hemp is simple, as it is a solid wall construction,=20 rather than a cavity wall, lime rendered on the outside, and lime=20 plastered. Clark is working with Ralph Carpenter and others, and Bath=20 University is testing some trial blocks, building dummy walls, and testing= =20 the downward pressure of a roof weight. "If we succeed, this will have=20 wider use in the building industry, as putting it into a block cuts labour= =20 costs. If the big boys adopt it, there are considerable environmental=20 benefits. We want to demonstrate that the product can be used safely for=20 building, then show it can be used on a large-scale, competitive basis (and= =20 it has to be very competitive), then we have to show it's a long-term means= =20 of building." The ideal, says Clark, is to grow hemp locally, process it locally and=20 provide the blocks locally, if possible. It has to go through a hardening=20 process for use in buildings. East Anglia, where hemp is grown, has become= =20 a testing ground, and the Essex company Hemcore is the only large-scale=20 processor in the UK, according to Mike Duckett, the managing director. "We= =20 are quite close to producing a prototype block," says Duckett. "About 3,000= =20 hectares of industrial hemp were grown in this country in the past year,=20 under contract to us. It's a significant operation. "The use in building materials is a new market we're keen to promote. About= =20 5,000 tonnes of this woody material is now being used in the French=20 construction industry every year. The public interest is phenomenal. It no= =20 longer attracts only the yoghurt-and-sandals brigade." Sally Harper and her partner, Tony Williams, agree. They set about building= =20 a kitchen extension at the rear of their old Oxfordshire cottage with their= =20 own hands, using shuttered hemp and lime. "We had an oak timber frame built first, and used vertical softwood struts= =20 at 600cm intervals, and then shuttered up the hemp on the outside of the=20 timber struts. It was very quick. "The room is 18 feet by nine and it took us five days, but it would have=20 been less if the site had easier access. The recipe we used was: three=20 buckets of hemp, one of lime, one of water; you mix it all up in a cement=20 mixer, then pour it between the vertical plywood sheets and tamp it in. "By the time you've got it all into the shuttering, which was about 2=B75ft= =20 high, it's solid and you have to take away the plywood straight away or it= =20 would stick. "The walls cost us UKP700. They take about five weeks to set really hard.=20 You can't do it if the temperature drops below 5C, or it wouldn't dry, and= =20 you can't do it when it's too hot, as it might crack." And are they happy with the end result? "The hemp has lived up to my=20 expectations," says Sally. "The walls really breathe, and moisture can go=20 through them in the form of moisture vapour, instead of being kept in the=20 building." For more information about building with hemp, view=20 www.projects.bre.co.uk/hemphomes
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