I live in Hotnitsa, near Veliko Turnovo, where my family owns a house and adjoining land. This summer we are going to build a house using straw bales instead of bricks or concrete. We want to investigate ways of building in eco-friendly ways. Our criteria for the build are as follows:
To minimise energy demand.
To use materials from renewable sources and/or with a low environmental impact.
To recycle materials wherever possible.
To build a comfortable, secure, healthy home.
We’ve just started the design and planning permission process and intend to have a completed house by September. This article is the first of several that will document the building process. I’ve heard all the jokes about three little pigs and the big bad wolf in relation to straw houses, so please suspend your disbelief for a few months and join us on what should be a fascinating journey.
Background
The first straw bale buildings were built at the beginning of the twentieth century in Nebraska, United States. Conventional building materials were scarce and straw was a reliable alternative. Since then three main styles of straw bale building have evolved:
Nebraska, infill and hybrid.
Nebraska style is where each layer of bales is set out like conventional house bricks. The bales are pinned together with stakes while the weight of the roof is carried by the bales. This style is referred to as load bearing and is not suitable if windows and doors comprise more than 50 per cent of the wall surface area. Nebraska-style straw bale houses can be ideal for self-builders because they don’t require great skill and are fast to construct.
The infill method is also called post-and-beam or timber frame. This style has a frame, usually made from timber. The frame supports the roof and the straw bales enclose the space. Openings such as windows and doors can be bigger using this method. This style is non-load bearing, which is often preferred by planners and the construction industry as it is an established way of building and therefore less innovative with a lower risk factor.
Hybrid methods combine both of the above. With a hybrid straw bale it’s possible to use infill on the south side of a building with large windows that maximise solar gain and load bearing on north facing walls where exposure to cold should be minimised.
A straw bale building should also have good boots, a good hat and a good coat. The “boots” refer to the foundations, which must be raised above ground level to keep the bales clear of ground water and splashing rain. The “hat” is the roof, which must overhang and protect the walls, and the “coat” refers to the exterior plaster, which is traditionally made from lime, applied in at least three layers.
Why straw bale?
I’ve been interested in construction for as long as I can remember. In recent years I have also become more knowledgeable about environmental issues. Putting the two things together led me down the alternative building route. Straw bale particularly captured my imagination, possibly because it reminds me of my childhood when I played houses in my father’s field in the UK using the materials to hand – frequently straw and grass.
In order to learn about straw bale houses I visited the Centre for Alternative Technology in Wales where there are demonstration buildings. I’ve also volunteered on a hybrid straw bale house where my job was to mix and put clay plaster on the internal walls. This job was laborious but satisfying. We started by mixing the clay with water and manure and treading it into a malleable form before spreading it by hand onto the straw bale walls. One tip for anyone thinking of doing this: wear rubber gloves!
Last summer my husband, one of our daughters and I attended a short course on straw bale building run by Amazon Nails (www.amazonails.org.uk). Amazon Nails is a well known straw bale building company based in the UK, run by Barbara Jones. Barbara is very experienced and builds straw bale properties all over the world. I’m delighted to say that she’s coming to Hotnitsa in July to work with us on our building.
The course we attended was based around an infill straw bale building in the north of England. Over two days 15 participants built the majority of walls (see pictures). We also learned about other eco-friendly ways of building, such as foundations made from old car tyres filled with aggregate and/or rammed earth; composting toilets; waterless urinals and solar-powered hot water. We were shown how to use densely compacted straw bales (to prevent fire and invasion by mice), how to use a bale needle to create half-sized bales and the benefits of Lego bricks when designing a straw bale house. It’s important to design a house that matches the size of your bales. Careful design and measuring between window and door openings prevent the need for inserting half bales. I’m off to buy a box of Lego now!
What next?
We are at the beginning of planning our own straw bale house. We have to decide which of the three building methods we’ll use and what other eco-friendly elements to include. This process involves a lot of research and I intend to find out about all of the following before including or dismissing them from our project:
Solar panels
Rainwater harvesting
Heating methods – solar, wood, etc
Floor and roof insulation
Passive solar design
Eco-friendly paint
Lime plastering
I imagine more things will come up during the next few months. I’m looking forward to sharing my findings with you. Any knowledge or information you have would be most welcome and if you’d like to be involved in the project let me know via features@sofiaecho.com.
Meanwhile if you would like to see some inspiring photos of beautiful straw bale houses here are a few websites to look up:
www.balewatch.com/275.cottage.html
www.blackrangelodge.com/lodge
