hempcrete to historic timber framed house

2013 Harlow

hempcrete contractor | lime render contractor | earth/straw lath and plaster repair

 

Working on such a beautiful old building was a real pleasure.

We insulated the building whilst retaining the character, curves and historic fabric of the building.

Cast hempcrete: £540/sqm

2 coat NHL2 and sand render: £40/sqm

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First we had to repair the historic earth and straw lath and plaster so we could use it as permanent shuttering and cast from the outside.
The external render is sand and cement and a lot younger than the structure.
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Brick plinth.
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The walls lean out with the structure, something the client and listed buildings officer wanted to retain.
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I curved the corners with a nail float before the hempcrete was fully hard.
Because I shuttered with flexible boards and spaced 150mm off the timbers I kept the exact contour of the walls just 150mm further out than it was.
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Another course of brickwork was added to widen the plinth and take the load of the extra hempcrete.
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The windows and doors were put in after we hempcreted, I was quite worried about this at first but it worked out ok.
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The water marks are where the hempcrete is drying through the earth/straw plaster.
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This gable had an additional stud frame work on the outside to take fixings for hung tile caldding.
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An awkward detail made simple by just feathering off the hempcrete around the corner.
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Here comes the mixer, its the standard forced action pan mixer that my custom built hempcrete mixer was based on.
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I was really pleased with my lime render on this build, it was the first build that I really felt like a proper plasterer- the other builders even called me spread. I rendered the whole 100sqm myself in 3 days for basecoat and 3 days for topcoat and
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Nice drip detail.
Nice drip detail to shed the water from the gable away from the walls.
New plinth.
Authentic curves, shuttering with thin boards and spacing off the frame has kept the exact curves of the building.
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Earth plastering always makes me smile.
The key that the plaster creates when it curves over the laths. This was our permanent shuttering, we then added horizontal battens at 600mm centres to key the hempcrete to and away we went.
We bought some ready mixed clay plaster but it just wasn't anything like the original. So we dug a whole in the garden, screened the clay and mixed it with straw..... much better. There was something missing though, the original plaster smelt sweeter
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Riq giving the muck his expert eye.
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