Committee member Phil is building a straw bale building in his garden to act as an office as he works from home. Follow his journey using this highly efficient building method.
February
Over the next few months, I’ll be reporting progress on my new garden office, which I hope to have built this summer (2024).
I’m a transport planner and highway engineer and work mostly from home in Kinver, currently in a wooden summer house.
As the name suggests the building is fine when it’s warm, but despite my best efforts to put in some insulation it gets a bit nippy in the winter. It’s also suffering from some wet rot, so needs replacing.
Why build using straw bales?
The first little pig was onto something – straw bales, a by-product of wheat production, make an excellent building material. Straw has a high insulation value and can act as a structural element. And unlike more conventional building materials like cement and steel, straw has a very low ‘embodied carbon’ value – that is, the amount of CO2 needed to make and use it. It’s not well known, but embodied carbon is a huge problem, making up almost half of total new construction CO2 emissions between now and 2050.
Straw bale construction types
There are two main ways of building with straw bales:
- Load bearing – where the bales act as the structure and the insulation
- Infill – where the bales are placed in a timber frame and act only as the insulation
I’m going to use the infill method as this will allow the roof to be built before the bales are put in place. It’s essential to keep the bales dry to prevent any chance of rot, and that’s much harder if the walls are being built in the open.
The straw bales are plastered with vapour permeable materials to keep them in good condition. This is typically lime plaster on the outside and clay plaster on the inside.
Progress so far
Matt Bailey of Wellspring Architecture specialises in this type of construction and is helping me plan it all out. We’ve pretty much settled on the outline design above, which will sit in the centre of our narrow garden close to a couple of mature silver birch trees.
The walls are quite thick at nearly 0.5m so the inside space is much smaller than the footprint of the building, but that’s OK as I don’t need a lot of room to work. The internal dimensions will be just slightly greater than I have at present.
What’s next?
Matt will be producing the detailed plans for construction over the next few weeks and will then be able to advise on the build. I’m already having discussions about the project with a builder who’s worked for us in the past. He’s not done this type of construction before but is keen to give it a go and to learn. One of my aims is to develop local skills in straw bale construction so others can benefit.
I’ll post again when I have the construction drawings.
June
Lots of progress to report on the Straw Bale home office – things are really getting going now.
A few weeks ago we received final plans and construction details from our Architect, Matt Bailey of Wellspring Architecture. We made a few changes to the windows, so the final building will look pretty much like this:
We’ve gone to a local builder, Alan Gwilliam, who’s done work for us before, and who’s going to start on the build proper in the next couple of weeks. Alan’s not worked in this type of construction before so will be getting help from Matt when he needs it. One of our aims is to increase local knowledge and skills in low-carbon construction, so I’m pleased we’re doing it this way.
We’re aiming to avoid the use of cement in the construction as it’s so high in embodied carbon, so we’ve gone for steel groundscrews, which are becoming very popular. We went to GS4U for the installation and they were very professional and quick. The screws were installed in about four hours without any fuss or mess. Here’s a couple of pictures showing them going in and the finished pattern.
The next stage will be to construct the “base plate”, a wooden beam construction that sits on the groundscrews and supports the floor joists, the straw bales and the columns going up to the roof.
I’ll do an update when that’s underway.