The Race To Start The Hempcrete

Following the oak frame raising the site was quiet for a few days.

Soon though it was a hive of activity again. The race was on to get the frame ready for the hempcrete. It was crucial to push on so the hempcrete could be cast and dry out over the remainder of the summer.

It was strange it seemed there was perhaps not so much to do but actually it was a huge amount of work and materials. My small build team though rose to the challenge.

First step was to install the floor joists and put down some temporary boarding.

Once this was done the rafters for the roof were cut and fixed. This though presented a few problems. A separate carpentry firm came in to cut the roof and while they did a very good job there were a few teething problems. The materials used in the house are relatively unusual. So some of the detail is quite bespoke particularly air tightness details. We also had a few roof-lights missed off the plans!! These were all sorted though without too much bother. One small area remains problematic due to an unexpected interaction of rafters. No easy solution for this one and options are still being considered.

Next was the construction of a softwood framework around the outside of the oak to provide support for the hempcrete and create window openings. As you can see from the photos this was no small task. The first floor and gables have special plywood fins fixed to the frame to provide a fix for cladding over the finished hempcrete.

The window reveals are an interesting detail. They are constructed from a material called wood wool. It looks a bit like compressed wooden spaghetti!

It is made from long wood fibres stabilised and bound by cement binding agent.They have many interesting properties. They key ones for my project are: vapour permeable, durable, stable, low environmental impact, non-flammable sound absorbing and noise insulating. The splayed reveal design internally should provide a pleasing aesthetic while allowing plenty of light into the building given the 350mm thick walls.

Everything was falling into place; even the weather had been kind. We were going to be ready for the hempcrete. A small team from Hemp-Lime Construct would work with my team and myself to hempcrete the house.

I had decided to source my lime binder and hemp direct from France. There were several reasons for this but it made most sense for my project. Everything was set up to go, my supplier in France had all the materials ready to dispatch, but this was a self-build it shouldn’t be this easy. The next day the news announced a strike at Calais and massive queues and congestion at all ports. My supplier couldn’t get a transporter to collect the materials. When the situation would change was unclear.

Time was running out. Would my lime and hemp arrive? Or would I be paying a hempcreting team to be drinking tea and discussing lime binders??? ….