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Straw and hemp house passed 'safe'

A house made of hemp panels and straw is as fire resistant as houses built of conventional building materials, even at 1000 degrees centigrade, research has revealed.

Bath’s BaleHaus@Bath building, made from prefabricated hemp and straw-bale, had a panel used in its construction heat tested by a team from the University of Bristol.

The panel had to withstand the heat for more than half an hour, but lasted two hours without failing.

The house is made from prefabricated cells of timber filled with straw or hemp, rendered with a lime-based coat.

BaleHaus@Bath is part of a research project into how renewable building materials can be used for homes of the future. The research work has been funded by Carbon Connections and the Technology Strategy Board.

Construction materials researchers from the university will also be monitoring the house for a year for its insulating properties, humidity levels, air tightness and sound insulation.

The ModCell BaleHaus system is the brainchild of White Design in Bristol and Integral Structural Design in Bath. It was used last year by TV presenter Kevin McCloud to build an eco-friendly house in six days for the Grand Designs Live exhibition.

Readers' comments (2)

  • I'll admit that my understanding of fire is limited, but surely making statements on fire safety based on solely a heat test is insufficient?

    I'll grant that items can catch fire from excessive heat, but I always thought that something like straw would be more likely to catch alight from exposure to a flame. I would therefore wonder if a small fire, for example from a short-circuited kitchen appliance, could set a straw bale wall alight quite quickly? In which case the panels may not be as safe as conventional materials.

    Would any fire safety experts like to correct (or possibly agree with) me?

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  • Hi Andrew,

    The fire test for the ModCell BaleHaus is a standardised test for building systems.

    The fire test chamber is a 3 m x 3m by 1 m open sided furnace. The building system being tested closes the open side. Twelve propane jet burners set parallel to the panel are lit and bring the temperature up to 600°C within 5 minutes and continue up to 1000 within an hour.

    To put this into context, paper will spontaneously combust at 357°C.

    After 2.5 hours the test was stopped.

    The targets were to demonstrate the system could achieve half hour then go on to a one hour fire rating. 2.5 hours is an outstanding result for any type of building construction.

    For the last 45 minutes of the fire test straw was the only material preventing the flames from escaping.

    I hope that reassures you that BaleHaus is actually safer than most forms of construction.

    Regards

    Craig White
    Director
    ModCell

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