hempcrete floor
2012 London
construction design | hempcrete contractor
As far as I am aware this was the first hempcrete floor in the UK.
Engineered timber floor boards were used as a finish over the top.
It was 22sqm and took 1/2 a day to install the LECA and a day to cast the floor with myself laying and Rob mixing.
The hempcrete was 150mm thick.
The site had been levelled and hardcore compacted.
The first layer to go down was 200mm of coated LECA.
LECA is light expanded clay aggregate and the coated version doesn't wick up moisture acting as a damp proof layer so plastic membranes are not necessary.
It is insulating and it can take loads.
Once I had levelled the LECA I spread boards over it to walk on.
The small mixing area only allowed a standard cement mixer.
The mix was 100 litres of hemp shiv : 30kg of Prompt : 27 litres of water with 1 flask of tempo. The tempo is basically citric acid and retards the set of the Prompt to give you enough working time, otherwise it sets within about 5 mins.
I started laying from the back.
The timbers set in the hempcrete are for the finish floor boards to fix to.
I cast the hempcrete in two stages, first roughly laying hempcrete over the whole floor then going back over it with a bit extra to set the timbers in and level the floor.
