Grow a green house

Hemp House: Chris Berry reports on a family building their own home from the crops they grow

Being ahead of the game can have its snags. The Voase family came up with a new way of building a house and promptly had their planning request rejected by the local council. "One of the reasons they gave was that they thought the building was going to be lime-green," says Margo Voase.

"They had read that this was a 'green' project and since we were proposing building with hemp-lime, they brought together the two words lime and green. It led them to assume we were coming up with a quite different house colour to the one you see here, which is its natural finish and in keeping with the area." Ten months later the misunderstanding was cleared up and the permission was granted.

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The plan was to develop what was previously a grainary, with wagon sheds below, and is attached to a barn. But this is no ordinary farm project. The Voases are prompted by a determination to illustrate their belief in the hemp which is is cultivated from cannabis plants of the sort developed for their fibre, not the type whose leaves are prized by marijuana smokers. The potential that this fibre has for the building trade as a green and sustainable material looks very exciting. "You can construct a solid wall when the hemp is mixed with lime," says Nick. "It provides a breathable, insulated wall that meets all of the building regulations and provides a very pleasant environment for living in."

Martin and his wife, Margo, thought there was no better way of proving that than by having their own new home built from it, using hemp-lime plasters and hemp-clay. "The walls of the property have been constructed utilising a fine grade of a hemp-sand-lime mix," says Nick. "The colour you see is the natural colour of the mix. We haven't added anything to it. The bulk of the wall is made up of hempcrete – a ratio of three-to-one hemp to lime and no sand.

"It has thermal mass, which means it holds the heat. The building doesn't just cool off when the heating is turned off, the wall gives the heat back to enable a more constant temperature. We have also laid a hemp-lime floor."

They contacted the pioneer of this sort of building, Ralph Carpenter of Modece Architects, from near Bury St. Edmunds. "He was the person who gave us the confidence to go ahead and use hemp in the renovation project," says Margo. "He hasbeen using hemp for building longer than anyone else in the UK."

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A local builder Mike Turner of Hedon, a member of the Federation of Master Builders, was engaged by Martin and Margo engaged him to build it and he has been impressed. "It's my first building using hemp and I can definitely see that it is the future for house building," says Mike.

Nick Voase first started growing hemp her at Inn Carr Farm, Baswick, near Leven, between the growing of wheats as part of field rotation. But Nick and his parents soon realised the potential of what they had taken on. "We had been looking for a good break crop," says Nick.

"We had tried lupins, evening primrose and borage before we started growing hemp. This year it will take up half of our land."

Hemp grows eight to 12 feet tall and is one of the fastest maturing crops. It takes just four months to become a woody crop, where some trees may take 20 years. The National Farmers Union weere among those who many years ago began advocating the virtues of growing crops for industrial uses, such as linings for car doors and dashboards and building materials. But no-one was listening very much. Today, the Voase family are not just convinced, they are almost evangelical in their approach to hemp which has two main contituents, both very useful.

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It's the woody core, called the "shiv", which is is used for house building materials. The Voases main markets at the moment are in horse bedding and pet bedding sold at garden centres, pet stores and equestrian outlets. The fibre wrapped around the outside of the shiv's stem has a multitude of purposes such as loft insulation. Mixed with bioresins it can be used to make doorskins and parcel shelves for cars.

"Our fibre goes to a bed manufacturer in Leeds who is using it in mattresses," says Martin. "That's where over 90 per cent of our fibre is heading. They are using 3.5 tonnes of fibre a week and by Christmas we anticipate they will be up to 5.5 tonnes a week. It sells the 'green' story. They are utilising natural products rather than man-made and it is a market that we feel will grow even further, with many other bed manufacturers in the future. To indicate hemp's toughness and durability in its natural state, Martin demonstrates how hard it is to pull apart.

Hemp-growing has been around for centuries. But finding markets for new products can be difficult. Even so, Nick and Martin have transferred half of their 650 acres over to it because of their confidence that it had a future.

It might take some time for there to be enough of the crop grown to convince a major house-builder that hemp ticks all the right boxes and is the way forward. But Nick believes the growing strength of the self-build and eco-build markets will provide sufficient demand in the meantime.

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"We are already in a position where we have buyers for nearly all of what we produce. There isn't the land around here available to buy to increase the quantity we grow any further. I fully envisage looking for extra growers. I believe it's a good opportunity for other farmers. The crop fits in well and will grow on most types of land. It is not sown until early May and you harvest it by cutting and baling, there's no combine time involved."

The Voases have not been without their problems since they started growing hemp, none related to the quality of the crop itself. A company set up to trade in hemp, which Nick and Martin were dealing with, ceased trading and last year they lost a quarter of their crop in a store fire.

Martin and Margo have also been fighting a battle to ensure that three River Hull pumping stations do not close, as was proposed a while ago. They have presently received a reprieve. Their concern is not just that their own farm, which runs up to the river's eastern bank, may see 30 per cent of their land unfarmable, but also for the impact the closures would have on the outlying areas of the city of Hull just a handful of miles south.

"If the pumping stations at Wilfholme, Hempholme and Tickton were all closed it would raise the water table and we would lose what is some of the most productive land in the country, but that would also mean that there wouldn't be the carrying capacity to absorb water when floods occur and the run off would flood areas such as Orchard Park, Dunswell and Kingswood in Hull."

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It could also curtail the next big good news story in housebuilding. Nick and Martin are no experts in conventional building techniques, but they feel that price-wise hemp is competitive when you compare the savings to be made in the future on heating costs. The family is convinced hemp house construction is one of the ways forward for low-cost sustainable house building.

They point to a recent example where four sustainable low-cost houses were commissioned by the National Non-Food Crop Centre based at York University, to be built for 75,000 (excluding groundworks) at the innovation park of the Building Research Establishment, near Milton Keynes. They understand that the hemp house was the only one completed on time.

YP MAG 20/11/10

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