3 Oct 2011, 5:50 PM
Self-builder Mark Harry shares the story of his demonstration Hemp and Lime shed. "I wanted to design and build a Hemp and Lime hut outside my office so that I could show potential clients what sustainable healthy buildings are all about. I have worked from home for the last 18 years and built a small office in the old chicken run at the bottom of the garden. Outside my office was an old timber shed which had mice running everywhere through the rotten boards. So it had to come down.
This was my chance to erect a Hemp and Lime Hut in its place. Mice and vermin hate Hemp so I hoped that at least it would keep them at bay. As my budget was tight I opted for a 3 metre by 3 metres simple lean to timber structure with the roof orientated to South for future Photovoltaic panels at a later stage.
I am involved in the design of refurbishment and extensions to local dwellings of all sorts. So when a client’s chimney was being demolished I acquired all the old bricks with lime mortar. The mortar was removed from the bricks quite easily and kept for reuse as hardcore to a base for a lamp post (from another job). The course of bricks went down on the existing concrete base and the timber shell went up in a couple of days.
Very soon after, a storm brought down part of a tree containing my daughters tree house - I took down all the plywood and kept the best for shuttering. While taking about my project to a friend he said he had an old
cement mixer in working order that he has no use of now and I could have it for nothing.
It was now just before Christmas 2010 and I had to wait until end January to start mixing the hemp and lime as the weather was so cold sometimes down to -10 degrees C. I soon found out that mixing up the hemp and lime was not straight forward especially with a mixer with no stand and only one internal paddle. There was no choice but to buy a new mixer. I was soon getting the hang of things and could mix and lay two sides of one lift per day. That was taking into account I was doing it all by myself, preparation and cleaning up.
At the corners I had cut up lengths of drain pipe to form round corners with the hemp and lime. Also within the walls I wanted to place some glass bottles and wrap LED tape around so it would become a feature. Collecting bottles became a family obsession, and my wife found some coloured glass tumblers that were the right
length. I wrapped 5 metres of warm white LED tape around the tumblers and then carefully laid the hemp and lime mix around each tumbler.
The walls were now all erected and from resalvaged timber I laid the floor with Hemp and lime as infill between the joists. The old t&g boards from the roof of the old shed were now laid as floor boards. As the inside walls were flush with the timber frame a weak mix of lime was ragged onto the inside walls. This in time went hard and I just love the texture and smell. It has now had several coats of Humpty Dumpty breathable clay paint.
The roof had Tyvek breathable membrane applied and second hand Rosemary plain tiles to match the adjacent Office. The rain water goods were Lindab galvanised with rafter brackets. The top of the rafters were notched, brackets fixed and the t&g boarding fixed to achieve the exposed rafter look that I was after.
The external walls were given a scratch coat of Hemp and horse hair. After 10 days they were ready for the top coat of lime render - about two weeks later 4 coats of Lime based paint, Strong Red was applied.
A few old kitchen units with a new worktop were soon fixed inside and the final touch was the front door with our old front door Knocker from our first house that we had kept all these years.
All in all it has taken me just over a year to complete the Hemp Hut working most weekends and between cold snaps and holidays". - Mark Harry