Mullumbimby Hemp House

Front of house

Location:
Mullumbimby, NSW North Coast

Type of Build:
New two/three bedroom residence

Owner:
Andrew Wadsworth and Meggie Danielson

Designer:
Jaye Irving, Barefoot Sustainable Design, barefootdesign.com.au (concept design)
Graham Harper, Harper Design Arc (detail design and plans)

Builder:
Corey Thomson
Xylosinuous Building and Design

Size:
125m2 plus decks (170m2 including decks)
 210m2 incl studio (see separate entry)

Cost:
$287,000 plus finishes and kitchen est $40,000, est total $327,000
Est $390,000 including studio

Date of construction:
August 2014 – April 2015

Purpose of Build:
Residential home

Choice of Material:
Andrew was interested in using sustainable building materials and Architect Jaye Irving linked Andrew up to the “Green Building Centre” at Byron Bay (greenbuildingcenter.net.au) and suggested he have a look at hempcrete.  In 2013 Andrew did a hemp building workshop with Hempcrete Australia where he met builder Corey Thomson. Corey then put Andrew in contact with the Australian Hemp Masonry Company.

Climate:
Zone 2 - Warm humid summer, mild winter

Local Council:
Byron Shire Council

Obtaining Approval:
Building surveyor Dwane Roberts of DP Roberts Planning Solutions was engaged to assist with the approval process and Andrew had no problems obtaining Council approval.

Rear of house

Construction:
Builder Corey Thomson of Xylosinuous Building and Design, was contracted to undertake the main construction works.  Andrew arranged the kitchen and rendering separately

Footings:
Concrete slab on ground

Floor:
Polished concrete, with timber in the bedroom and kitchen. The concrete was set down in the kitchen to allow the timber floor to finish level with the polished concrete

Frame:
Timber frame, 90mm untreated pine, with T2 termite treated pine for the bottom platebottom plate. The frame was made on site.

Walls:
300m thick hemp walls using AHMC binder and hemp. The frame is centrally placed and the walls were 300mm thick to fit the builders existing formwork.  Hemp walls are finished externally with a sand lime render and internally are partially rendered with AHMC hemp render and partially left unrendered.  The second storey is clad in corrugated Zincalume with Kingspan Aircell R2 insulation. The the double height hemp feature wall at the front is clad externally in Hibiboard short timber (not sure what this is, can you provide more detail?). Internal partition walls were finished with plasterboard

Rendered window reveal

Windows:
Aluminium single glazed and second hand timber windows

Ceiling:
125mm Bondor Insulroof panels

Roof:
Bondor Insulroof  panels providing R 3.53 and finished with corrugated Colorbond in shale grey

Heating:
None

Cooling:
Ceiling fan in main living area

Wall construction:
The walls were constructed by Builder Corey Thomson. He had previously done a hemp building workshop with Hempcrete Australia and worked as the builder on a hemp extension at Maclean and did a hemp building workshop with Klara Marosszeky of AHMC as part of the construction at Maclean. A horizontal shaft compulsory mixer was used to make the hempcrete

Formwork:
450mm high Formply formwork that the builder had from rammed earth work

Internal showing half rendered and half natural hemp wall

Technical issues:
Problems were encountered with windows leaking, and insufficient fall in a bathroom floor but these problems were not associated with the hemp walls

Advice/Recommendations:
Get and architect or building designer that you can rely on and can work with.
Getting help from a planner to explain the process and get Council approval was of great assistance.
Andrew regrets not having more hemp walls but was constrained by budget

Contact:
Andrew Wadsworth
Andrew@mullum.it

Corey Thomson
Xylosinuous Building and Design
0419 715 820
Xylosinuous.com.au