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light earth (’leichtlehm’) - history
light earth is a relatively recent development in the millennia old earth building history.
the term
‘leichtlehm’ was first used in the german earthbuilding standards of 1944 and referred to mixes with a density of less than 1200 kg /cubicmetre.
there are, however, far older examples of the same technique around. new zealand has some pumice light earth structures that are more than a hundred years old. the
principle of a load-bearing timber frame with an earthen infill is an ancient one, and we have worked on some fine examples in germany, that were more than 800 years old.
the timber in these frames was generally still in very good condition due to the protection by the earthen infill.
the loam (clay, silt and sand) keeps the timber at a constant moisture content of below 18%, often physically covers it and thereby protects the frame from vermin, the weather and fire.
unfortunately many ‘half-timber’ houses were damaged or even destroyed in the sixties and seventies when ignorant owners ‘renovated’ their homes with cement-based plasters instead of traditional lime-based plasters on the outside.
reduction in ‘breathability’ introduced by the cement led to a moisture build-up inside the wall that started a rapid decomposition process in the wood - the same thing has happened here in new zealand with the infamous ‘leaky buildings’ recently.
the combination of structural timber frame and insulating light earth panels is
particularly suitable for wet and cold climates.
by applying
sound design practice and honouring the tradition we produce structures that have the potential to last for many centuries, gaining character as they age in dignity.
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