A house made out of straw. It’s perhaps a surprising concept but this type of ecological construction is going through something of a boom period in Europe, a century after the technique was imported from the US.
We’re in France, where around 700 such buildings are registered. As a material, straw has many plus points, notably the economic aspect, even if some experts urge caution.
Christelle Dupont has been working on straw building sites since 2006. She explained a little about the project:
“Straw and mud are only used for the walls, and a house of course is more than just walls. The walls account for about 15-20 percent of the total budget. It’s very comfortable and you make lots of energy savings. Over time the house will more than pay for itself.”
There are different techniques, each with it’s own advantages. On this site near the Breton town of Dinan, the owner has opted for a wooden structure to house the straw bails, which can be placed either flat or on their ends.
“If we put them down flat, we’ll get a wider wall but one that will provide the same insulation. Because, flat, the air gets in more easily, as it follows the horizontal direction of the fibres. But when the bail is on its end, the wall is thinner but it offers the same insulation because, with the fibres being vertical, the air finds it more difficult to get through,” explains Christelle.
For anyone worried about a potential fire hazard, the solution is of course, not chemical. The bails are simply dipped in a mix of water and mud or lime. This coating will provide a decent fire protection.
One volunteer told us it also helps prevent damp: “Here we’re soaking the side of the bail in order to protect it. If any humidity builds up inside the bail, it’s not very good for the straw.”
Once dry, the bails are ready to be put into the wooden structure. They will then be given another coating of three centimetres to regulate the temperature of the walls.
Special attention is paid to where the structure could be most vulnerable, as Christelle points out:“This is the west facing wall, so the wall that is the most exposed to storms. This particular house is very tall and, being in Brittany, it rains alot so we’ll put on a wooden siding to reinforce the gable.”
Straw houses are often the result of good teamwork and the workers are in fact volunteers who have their own building projects finished or in the pipeline.
A two-hectare eco-site has been built near the site. And straw isn’t the only material they’re using here: there’s also a house made of hemp and several others out of wood.
Pascal turned his passion for the environment into a profession. He’s been an eco-builder for over 20 years. He told us:
“For me, straw represents a living material that you find in this house but not necessarily in conventional houses.
“We needed about 150 bails of straw for the wood structure and about another 150 for the roof. The straw comes from a farmer who lives a kilometre away who sold us around 300 euros-worth for the entire house.”
Not only are the materials eco-friendly, they are also local, so transport is cheap and doesn’t leave a big carbon footprint.