Community project
Lime-hemp insulation
- Moulin des Etrebières
- 3 September 2024
- 9h08
- 0 comments
Novices renovate an ancient wall with hemp lime
In five minutes, six strangers are going to arrive at my house. They've come to learn a technique I hardly know. They're complete novices, yet I am going to entrust them with an entire wall of the large holiday rental I am renovating, which is due to open in the spring. The aim of the project is to insulate a 16-feet high wall with hemp and lime, to bring comfort and aesthetics to the spacious living area.
I'm both worried and impatient for the work to start. I've been preparing for this day for several weeks with Corinne and Thierry from the Echo des Logis association. They have the know-how, having used the technique themselves in their home at theEcolieu de la Gataudière and they have agreed to be my technical coaches for the community project.
The site
The renovation of the Moulin des Etrebières in Cheffois (Pays de la Châtaigneraie) follows ecological guidelines, including rainwater recovery to flush toilets, a wood furnace and reed filter sanitation. Solar panels are also planned on the barn roof.
The house can comfortably accommodate 15 to 19 people in an enchanting location in the heart of the Vendée bocage. Guests will come to get together with family and friends, to recharge their batteries in a natural setting and to re-discover the joy of handmaking. Skills workshops (DIY, gardening, cooking, sewing, etc.) will empower you with doing things with your own hands.
Lime and hemp
So what could be more appropriate than a community project for this lime-hemp insulation at Moulin des Etrebières? The principle is simple: volunteers get together to build something, learn a new skill and share a friendly moment. It sounds simple, but it requires a certain amount of planning and organisation.
Several weeks beforehand, Corinne and Thierry came to see the wall, confirm the feasibility of the project and decide on the technique to adopt. We opted for the formwork technique, which involves packing the insulating mix between the wall and a board parallel to the wall to create a formwork. In order for the mixture to hold against the wall over a substantial height, we first had to make a wooden frame slightly offset from the wall to serve as a framework for the hemp-lime mix, whose consistency upon laying is too soft to stand the height.
The mixture is compacted around the timber frame, with the wall on one side and the panel on the other. To ensure that the formwork is perfectly straight, screws are fixed to the timber frame every 12cm, and the screw depth is adjusted by laser so that the screw heads are all on the same plane, which will match the surface of the future wall.
Corinne and Thierry and I agreed on a date for the job and made a list of all the equipment we would need. In particular, we needed scaffolding to work safely at height, a concrete mixer to make the mix and wheelbarrows to transport it to the living room wall. We were lucky enough to have professional workers on site who kindly lent us their equipment.
We also had to estimate the quantities of lime and hemp needed for the job. We calculated the surface area to be covered, multiplied it by the average thickness of insulation required to obtain a volume of finished lime-hemp mix and, following the recipe recommended by the manufacturer, deducted the number of bags to be purchased. Corinne and Thierry supplied the buckets, trowels, sledgehammers and other trowels.
Lime and hemp insulation community project
With all that said, the most important thing was still missing: the volunteers! An advert shared on social networks and with local associations (Maisons Paysannes, l'Echo des Logis) quickly led to the recruitment of 6 participants. They volunteered to learn the technique and then apply it to their own renovation project.
The project had been estimated to take three days, but thanks to everyone's motivation, Thierry's sound advice, Corinne's sympathetic guidance and a faultless organisation, we finished in two days, despite unforeseen circumstances. Because the wall wasn't perfectly vertical, I had underestimated the average thickness of the insulation, and I had to go and get supplies of lime and hemp before the second day's work started so that we didn't run out.
On the big day, the participants arrive and we get to know each other over coffee and the traditional Vendée brioche. Everyone has their own renovation project and is keen to try their hand at the insulation method. We quickly get down to work and organise ourselves into teams. One team is responsible for mixing the lime and hemp in the cement mixer and supplying the site with wheelbarrows full of the mix. Two other teams start attaching the formwork and tamping down the mixture.
You start at the bottom of the wall with the first formwork panel resting on the ground. When this first formwork has been filled, the second panel is fixed on top of the first and you continue to fill, packing it in. Next, carefully slide the first panel sideways to detach it and place it on top of the second panel. Repeat until you reach the top of the wall, where you finish by tamping the hemp-lime against the wall by hand.
A friendly time
The work is done happily, while chatting about our respective projects. The participants ask our technical guides many questions. During the pot-luck lunch break, I suggest a tour of the house. Then it's back to work. At the end of the day, all volunteers expressed their pride in the work they had accomplished and their desire to take part in the rest of the project. Next step is the lime-hemp-sand coating on 23 October!
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