Kyneton Hemp Bed and Breakfast

Rear view of studio

Location:

Kyneton, Victoria

Type of Build:

Two storey studio in heritage listed area, attached to rear of existing building.

Owner:

Joe and Deb D’Alo

Designer:

Ian Murray, Joe D’Alo and Deborah Varney

Builder:

Joe D’Alo

Size :

67.5m²  total; 40.5m² downstairs and 27m² upstairs.

Cost:

$165,000

Date of construction:

January 2012 to lock up stage in 4 months.  As a July 2014, still not finished, will need a further 2 months to complete

Purpose of Build:

To provide separate guest accommodation to be used as a Bed and Breakfast.  A unique experience for guests to stay in a hemp cottage.

Choice of Material:

Joe and Deb had been following the development of hemp construction for about 15 years. They have an interest in natural building and Joe had worked on both rammed earth and strawbale buildings. He saw the flaws with each of these construction types, such as the thickness of the walls for a strawbale building. Joe saw hemp construction as addressing some of the disadvantages of these other natural building methods, so with hemp also providing a combination of thermal mass and insulation, the choice of hemp for his own build was obvious. Hemp is an ideal building material for the climate in the region, as it has good thermal insulation whilst still providing some thermal mass for energy storage.

Timber rain screen finish

Climate:

Zone 7 – Cool Temperate

Local Council:

Macedon Ranges  Council

Obtaining Approval:

Council approval was granted for this build in a heritage area. A private certifier/building surveyor was used and there were no particular issues with the hemp construction.

Construction:

The whole build was carried out by Joe D’Alo who is a licensed builder. A carpenter with concrete formwork experience was employed. There was also a team for the hemp-lime mixing, filling the formwork and tamping.

Footings:

Concrete slab on ground. Concrete slab is a thickened edge raft slab with internal beams and expanded polystyrene edge insulation.

Floor:

The ground floor is tiles over concrete slab.  Upper storey – Alpaca carpet in bedroom and tiled bathroom. 

Frame:

Joe made the timber frame on site.

Walls:

Joe made the timber frame on site, using Australian Hemp Masonry Company (AHMC) binder, cast around 90mm structural pine frame. Internal walls were finished with a first coat of AHMC Binder and sand and a second coat of Plastalite lime/gypsum plaster. External walls were clad with Spruce Thermowood, which was left to naturally grey. For the external walls 25mm timber battens were fixed over the 10mm permanent magnesium oxide (MgO) boarding then clad with Spruce Thermowood weatherboards.  The 25mm gap between the MgO board and cladding creates an insulating layer.

Inside ground floor

Windows:

Double hung, double glazed timber windows. Permanent formwork was installed around the windows and doors.

Ceiling:

The exposed 20mm Supaboard Magnesium Oxide board floor of the upper storey acts as the ceiling to the ground floor.  Upper storey ceiling is 10mm Supaboard Magnesium Oxide board which was stopped and finished in a similar fashion as standard gyprock plaster then painted with a breathable paint. 250mm of “light hemp” (hemp wall material with less binder and no sand) was cast over the Magnesium oxide board as ceiling insulation.

Roof:

Corrugated galvanised metal sheet roofing is used.

Heating:

 A wood heater is planned to be used in an old fireplace, but Joe and Deb have found that the building stays warm in winter without heating.

Cooling:

The building uses only natural ventilation. Joe and Deb found that on a 40^o C day the downstairs of the studio stayed a much more comfortable 25 – 26^o C.

Upstairs under construction

Wall construction:

Joe is a licensed builder and carried out the wall construction himself, using a 360 litre diesel pan mixer hired from AHMC. Prior to construction Joe attended a Hempcrete workshop in Maleney, Queensland, but found the course lacked detail particularly when it came to how to specifically deal with window and door openings.

Formwork:

Magnesium oxide board was used as a permanent formwork on the external side of the wall. Formply was used for the internal formwork and rather than being attached to the frame it was braced against a timber stud on the floor so that there were no holes in the hemp wall. 

Section Diagram: 

Technical issues:

Hemping between the exposed upper floor joists was difficult. The 35^o ceiling was fine to work with but the 47^o ceiling was too steep and was awkward to build. Joe recommends that those interested in hemp building need to think about how to deal with window and door opening, in terms of lintels, flashing and how the render is to join the timber (window or door) frames.

Advice/Recommendations:

Joe found that using an external cladding and permanent formwork on one side of the hemp wall made the walls quick and easy to go up, because you only have to raise the formwork on one side, rather than both.  Although Formply was used as the formwork board, ply or OSB would have been quite suitable and cheaper. The external cladding was also advantageous from the point that the timber weatherboard cladding used maintained the look of the other outbuildings.  A rendered wall may have looked out of place.

Joe recommends runing electricals through conduit through the hemp walls. The mixing and tamping of the hemp-lime material is initially fun and therapeutic, however things can quickly change and the process can become a long and arduous task which will test people’s spirit.  A large, trained team might cost more in direct labour but the benefit will be in getting the hemp walls constructed quicker thus allowing them to dry (up to 6 weeks) before rendering.  The timing may be of particular importance if seasonal weather conditions are extreme.  Hemp lime building shouldn’t be undertaken when seasonal conditions are extreme, i.e., frost.

Contact:

Joe D’Alo

joe.dalo@bigpond.com