STRAW BALE BUILDING IN ULSTER
From Building for a Future magazine Winter 1997
There are now at least three straw bale buildings in the North of Ireland and at least one more planned. Two are in County Down and the other in Clones, County Monaghan. These followed from the promotion of the straw bale idea at Construct 96 by Barbara Jones and a group of architecture students at Queens University We built a demonstration building and partially plastered it in a day or so.
Following this the Steiner School in Holywood, County Down have completed a small (3m x 5m) office used for fund-raising, which is located in the school grounds. It was built by parents and friends of the school with help from Barbara Jones. The office is regarded by the school as a temporary structure, and planning permission was not sought. It is built on nine concrete footings with a suspended timber floor with half bales hung between the joists as insulation. The walls are load bearing straw bales with steel ladder wall plates. Timber windows which were donated to the school after the openings were formed leaving some detailing problems. The roof is a timber flat roof construction supported on central roundwood poles, with a butyl sheet covering. The curved end complicated it a bit. The building is rendered with a lime plaster and given an orange pigmented lime wash which looks very attractive. The building was partly funded by "Aim to Sustain" a grant scheme supported by Coca Cola, Environment and Heritage Service at the DOE and Northern Ireland Environment Link.
Cedar Integrated Primary School in Crossgar is in the process of constructing a straw bale nature study class room. This will be ready in the New Year along with the main school buildings which are of conventional (low energy efficiency construction). It is intended to be a part of an environmental area which includes a small river and a proposed willow walk. The building is being built by parents from the school and students at Queens University Belfast and was designed by Tom Woolley, Professor of Architecture at Queens. This was the first straw bale building to get planning permission in Northern Ireland and is claimed to be the first to obtain full building control permission .The building sits on a reinforced concrete raft with the first row of bales pinned to the foundations. The load bearing walls are reinforced with Hazel staves coppiced from Toms garden. These are driven in at regular intervals every second row. The wall plate is strapped to the foundations with nylon strapping, a technique which we found to be very successful. Polypropylene tubing was cast into the foundations to take the nylon strapping.
The roof is constructed from roundwood poles of Douglas Fir from the nearby Castlewel Ian and Tollymore forests. The rafters will be visible from the interior. The walls have received a scratch coat at the time of writing with a mix of lime putty and sand specially made up by Narrow Water Lime Services who are becoming familiar with straw bale buildings. The sloping roof is covered with plywood and a butyl sheet and 100 mm of polystyrene insulation (CFC and HCFC free donated by a Northern Ireland supplier) It will be covered with 100 mm of soil and planted with wildflowers from a local see co-op. A large South facing window will create some passive solar gain.
The plan also has a rounded end which helps to give stability to straw bale structures and this will serve as a story telling corner. The teachers and children , who have been very excited about the project have designed a truth window. The building has been financed by money from the local authority landfill tax funds, donations of materials and Shell Better Britain.
The experience of building was that the straw bale walls were the easy part . The roof proved to be quite a difficult task, especially the curved end of the building as none of us were experienced joiners and the plastering which we did straight onto the straw dragged into winter which made it harder to find dry days. The foundations maybe didn't need to be so massive and footings may have worked just as well. The strapping turned out to be a very quick and easy method compared to threading the bales onto threaded bar and bolting the wall plate on.
The Ark Permaculture Centre in Clones, Co Monaghan are building a sophisticated round thatched straw bale building which is to be a family home. It has been built by people who have come on the building courses throughout the summer of 'g7. The house is about 7m diameter with a masonry stove and massive chimney in the middle. Around this a spiral staircase runs up to the first and second floors which are within the steeply pitched thatched roof. The foundations are concrete with straw bales laid in a grid pattern within the concrete as insulation. On top of this load bearing straw bale walls go up to first floor level with splayed windows letting light into the earth plastered interior. Dormer windows on the upper floors let the thatch flow over them for ease of construction. The round-wood timber roof hangs from the central column around the stove and the underside of thatch now visible from the inside will be lime plastered to guard against fire.
One aim with the Clones project was to use entirely locally grown materials and while this was achieved to some extent . Much of the timber was thinned from surrounding land and mud was used from nearby. However a lot more concrete was used in the floor than they hand hoped and some joinery timber had to be bought in for the windows etc. Thatching while quite beautiful to look at , proved to be very[expensive and time consuming and relied on the goodwill of the thatcher. This building will be one of the first straw bale houses to be lived in and one of the first two story straw bale buildings.
Another straw bale classroom planned for the Rural College Draperstown,County Derry has run into some problems. Despite raising all the funds and getting all the necessary permissions the Rural College Management Board has got cold feet. Jude Stephens who has organised the project is now looking for another site in the area and hopes to build in 1998. Designed by Community Technical Aid, Belfast and it will be a frame structure using timber I beams. The straw will be used as infill and plastered with lime. The building will sit on six concrete footings and with a locally sourced cedar shingle roof. Such is the interest in straw bale building in Northern Ireland that others are proposed for County Fermanagh and another possible in Clones.
Our experience is that straw bale building is relatively easy and the methods can be learned by inexperienced people providing they are well taught . Getting the design and permissions right is more difficult and proper professional help should be used . We hope to publish detailed figures on the costs of the Crossgar building later in the year . While the bales are cheap we have spent more than expected on other materials and as most of the labour is free careful analysis is needed to establish whether straw bale buildings are really cheaper to construct . However the insulation levels and the customer satisfaction levels are high.
Authors: Anna Marie Higgs and Tom Woolley |
