Straw bale guesthouse at Rock Farm, Ireland.

 

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Reasons for building with straw:

Wise words from our client Alex Mount Charles at Rock Farm Slane.

I believe that the dissemination of straw bale building techniques will allow ordinary people to shift the dominant paradigm of home building, which is left in the hands of the “experts” and suppliers, by empowering themselves to build their own homes. Here’s my note of caution.
Having worked as an energy consultant and Building Energy Rating assessor for a number of years I have been summarily impressed and disappointed with examples of natural building techniques and so-called energy efficient homes. What on paper can look amazing in terms of energy performance and carbon savings, is not always realised in practice. You as the home owner are ultimately responsible for the energy performance and the integrity of your own home. So read up and ensure you’re getting the right deal.

   

Environmental-friendly

This works in 3 ways:

  • As the travel distance for the transport of the key materials is much reduced, less pollution and energy consumption results from sourcing the main building material from the fields.

  • The use of straw is seen as a method of carbon storage, as the carbon absorbed in the growing process is then trapped inside the walls for hundreds of years. So it’s as good as planting trees.

  • The internal environmental health and air quality inside the building will be enhanced by the breathability of the materials and the lack of chemicals which can cause health problems when we are forced into contact with them over long sustained periods.

Energy performance

A typical cross-section of a wall with lime render exterior on a clay skin on a bale thick wall with another skin of clay and lime-wash equates to a u-value of around 0.13W/m2·K. The latest Irish Building Regulations 2011 are to achieve a u-value of 0.21W/m2·K which would require the use of insulation and other potentially expensive materials to achieve the same. Unless the materials science moves on in leaps and bounds it will be hard to achieve u-values of 0.13 without recourse to expensive measures.

Low Tech

Also thanks to the “breathable” nature of the wall make-up it is easier to regulate internal temperature of the buildings during hot and cold periods, making a low grade heating system or PassivHaus design more feasible. I spent a week last October with Bee Rowan of Strawbuild on her course at The Centre for Alternative Technology and I came away feeling good and empowered to build my own straw bale buildings. As it’s a low tech building technique, a motivated individual could start building having completed a short course.

Locally-sourced material

I’m watching the green shoots of barley straw pushing up through the dry Meath clay loam on our farm and thinking “That’s my house growing in those stalks”. When you look at it like that, how could you not build with straw? The clay for the plaster is another local material and we could even quarry and slake the lime, as would have been done a hundred years ago in our beautiful lime kiln in the farmyard. But I think we’ll leave that for another time!

Good fire and sound protection

Straw bale walls have a very good fire rating: 1 hour for clay plastered walls, 2 hours for lime rendered walls. Whereas a typical timber frame dry-walled structure would have a 30 minute rating. Straw bale walls provide excellent sound insulation and have a positive effect on interior acoustics.