Wednesday 29 March 2017

Maclean Hemp Understorey Extension


Location:
Maclean, mid north coast NSW

Type of Build:
Understory extension to relocated weatherboard Federation Cottage

Owner:
Eshana Bragg and Peter Cuming

Designer:
Eshana Bragg prepared DA Application

Builder:
Corey Thomson
Xylosinuous Building and Design

Size:
Gross addition 94m2

Cost:
TBA

Date of construction:
August 2013 – flooring yet to be completed

Purpose of Build:
Multi purpose space, providing an office and workshop space for Sustainable Futures Australia, music studio, bathroom, laundry and woofer accommodation

Choice of Material:
Eshana looked at various methods of how to infill around the existing steel frame of the house. She wanted the material to have good thermal qualities.  She looked at using Hebel, but had some difficulty determining how to the Hebel would be detailed around the steel frame. Eshana saw Klara Marosszeky from the Australian Hemp Masonry Company at a stall at the Sustainable Housing Expo at Mullumbimby. Once she held a block of the hemp masonry she knew she had found her building material.   At the time she commenced building hemp masonry was a relatively new building material but she was willing to take a risk to use a sustainable material.

Climate:
Zone 2 - Warm humid summer, mild winter

Local Council:
Clarence Valley Council

Obtaining Approval:
Eshana spoke to the senior building surveyor at Clarence Valley Council before lodgement and also got the building surveyor’s input on the DA (Development Application). Council officers look at the property before the DA was lodged and were very cooperative and interested. The DA was approved in 10 days. AHMC provided an Alternative Solution report to be submitted with the CC Application (Construction Certificate).
 

Walls left unrendered under balcony

Construction:
The hemp walls were constructed over two workshops. The remainder of construction was carried out by Corey Thomson. A professional renderer was contracted to do the more visible parts of the render and Eshana, Peter and their interns carried out the remainder of the rendering.

Footings:
Concrete slab on ground

Floor:
Not yet completed but will be polished concrete

Frame:
Existing steel frame, with some of the frame altered to allow space for triple sliding doors in the extension. Between the steel frame a recycled hardwood timber frame was constructed to provide support for the hemp walls.

Walls:
AHMC binder and Ecofibre horse bedding hemp were used to construct 300mm thick hemp walls. The builder wanted 300mm thick walls to provide sufficient thickness between the timber frame and the outside of the hemp wall. The timber frame is centrally located and the hemp walls also cover the steel frame. The hemp walls are rendered externally. Eshana and Peter engaged a professional renderer to render the walls that are visible from the front of the house and the renderer used a first coat of the AHMC  hemp render and did a second coat of sand lime render over the top. The remainder of the walls were rendered by Eshana, Peter and their interns, who used a single coat of sand/lime render. They experimented with oxides to colour the render but finally chose to go with the colour naturally provided by the sand. Internally and externally around the entrance, under the protection of a large veranda, the walls have been left unrended. On the inside of these walls render has been used to create skirting and decorative window reveals.

 



Windows:
A mix of windows were used. Recycled timber windows, similar in style to the windows used in the upstairs part of the house, were used at the front of the extension. Taking inspiration from a historical cottage in Maclean built in the mid 1800s by a German settler, these windows were set toward the outside of the walls to provide deep reveals on the inside. Beautiful rendered decorative arches were put over the top of these windows. In the open plan workshop and office space high quality single glazed, using Viridian comfort glass, aluminium framed triple sliding doors from Yamba Glass were used, as well as large square tilt windows and louver windows.

Ceiling:
High ceilings of Gyprock Fyrcheck were installed on a treated pine frame, insulated from vibrational sound by rubber inserts usually used in solar panel installation. Ceiling cavity contains Greenstuff polyester bulk insulation with a double lay of insulation above the music studio. This was installed by Ian Brophy Builders. Eshana and peter report excellent sound insulation between the storeys of the house. Steel beams left exposed provide a sculptural element in the open plan workshop area, cotrasting with the high set ceilings painted bright white. Plywood together with acoustic insulation (to be installed)

Roof:
NA 

Heating:
Small fan heater. The extension does not need much heating.

Cooling:
Not needed, in summer the extension has remained at 23 degrees when it has been 37 degrees outside.

Niches in walls
Attractive window reveals


Wall construction:
The builder Corey Thomson had experience in rammed earth, but this was his first hemp build. The hemp walls were built on a row of concrete besser blocks at the bottom, with a moisture barrier under the besser blocks. Two workshops were conducted to construct the hemp walls. Klara Marosszeky and an assistant were paid to teach the workshops. Eshana and Peter paid for Corey Thomson and his build team to attend and the workshop participants each paid $300. The first two day workshop was attended by 10 people, mostly from the building industry and 15 people attended the second workshop two weeks later, with the builders and owners continuing an extra day to complete all the hemp walls.  The hemp walls were all done in the 5 days of workshops and the workshops used a 250L diesel pan mixer owned by the AHMC.  The initial render around the doors and windows did not work well and a professional renderer was engaged to remove and redo this render and it now has crisp edges.  The professional renderer also rendered over the besser block creating a render skirting.

Formwork:
Plywood formwork with attached horizontal timber walers, that the builder had from rammed earth construction. The formwork was secured with threaded metal rod, from one side of the formwork to the other. The holes in the hemp walls from  the rods were plugged later.


Section:
 


Technical issues:
  • Some areas of hemp wall were insufficiently tamped by workshop participants and the walls were crumbly, particularly in the difficult to reach area under the steel beams.  After a few weeks Eshana removed the crumbly section around a hole that had been left, dampened the area with a spray bottle of water and packed the area with new hemp masonry mix and covered the repair with a small piece of formwork screwed to the wall.
  • When by mistake a conduit was pushed out of alignment, the material was very forgiving and easy repair. Heat was needed to bend the conduit back into place and the hemp walls could easily withstand the heat of the blowtorch necessary to repair the conduit.
  • While the walls were left unrendered a Kookaburra pecked at a soft spot creating a hold in the wall for their nest. The hole created by the Kookaburras almost went all the way through the wall.  Once discovered the Kookaburra hole was easily patched up with more mix.
  • High quality rendering is a professional job and for Eshana this was a costly mistake when she had to get the work done again.
  • Eshana is still assessing the pros and cons of using a breathable wall in a damp environment.

Advice/Recommendations:
Go for it. Hemp building is a great community building activity. It can be done with an extended family, neighbours or a community and anyone can participate from kids to the elderly (Eshana’s dad at 80 was able to help out as much as other crew).
If you host a workshop, make sure that you keep the participants well fed, to keep them happy and avoid them flagging at the end of the day. For workshops also be well prepared, if you want any different shapes in the hemp have the formwork done prior to the workshop.
Hemp building is still a bit experimental and if working with an inexperienced crew this can lead to mistakes that have to be fixed and more expense. But it's worth it!

Contact:
Eshana Bragg
eshana@sustainablefutures.com.au

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


Main Arm Hemp Music Studio

Front view

Location:
Main Arm, near Mullumbimby, NSW North Coast

Type of Build:
Sound proof music studio constructed as infill to an existing pole structure

Owner:
Sheldon Lieberman and Olivia Laws

Designer:
NA

Builder:
Nicholas Jouin, Permastructure

Size:
Studio 21m2

Cost:
Est $45,000

Date of construction:
October 2015 – February 2016

Purpose of Build:

Soundproof music studio

Choice of Material:
Sheldon had seen Andrew Wadsworth’s hemp house at Mullumbimby. He was impressed that Andrew’s house was warm in winter whereas his house was cold. He was attracted to hemp because of the thermal advantages, the look of the hemp and that there was no need to paint it. Sheldon could also tell that the hemp walls has good acoustic properties.


Internal walls unrendered

Climate:
Zone 2 - Warm humid summer, mild winter

Local Council:
Byron Shire Council

Obtaining Approval:
As a non habitable structure, the studio did not require Council approval

Construction:
Builder Nicholas Jouin, of Permastructure, was engaged to construct the studio. He had a background in earthbag building and had built a hemp studio for Andrew Wadsworth at Mullumbimby.

Footings:
Existing concrete slab on ground. This slab was not level and did not have appropriate termite detailing. The concrete slab had to be levelled and termite traps were installed around the studio.

Floor:
Timber floor on battens and acoustic foam.

Frame:
Existing pole frame, with timber frame added between poles to support hemp walls.

Walls:
Hemp walls using AHMC binder and hemp. The rear wall is 300mm and the remainder are 260mm. This was because the existing concrete slab had a raised lip on the back wall that they wanted to cover. The back wall also faces the neighbours and the thicker wall provided additional sound dampening.
The walls were left unrendered internally and finished with Sodium silicate (Waterglass) to prevent dusting.  A number of cracks developed in the walls and these were covered with artistic render patterns. Feature render was also used around windows and doors.
Externally the walls were rendered by the builder, Nicholas Jouin, using AHMC hemp render.



Skirting detail

Windows:
PVC framed double glazed argon filled windows.

Ceiling:
Floorboards of room above, acoustic insulation, acoustic plasterboard, and acoustic wood wool panels.

Roof:
Existing shed structure.  Colorbond flashing was used on the back wall where there was a change in thickness of the wall from the existing Colorbond cladding and the hemp wall.

Heating:
Reverse cycle air conditioning (this is rarely used for heating).

Cooling:
Reverse cycle air conditioning. When in use the studio needs to be closed up for soundproofing purposes, the air conditioning deals with the heat generated in the studio from its use.

Wall construction:
The hemp walls were constructed by Nicholas Jouin of Permastructure. He gained experience working with hemp, building the studio for Andrew Wadsworth at Mullumbimby.  The builder used an old cement mixer to mix the hempcrete for the walls. I was mostly the builder and one or two labourers working on the project, with a maximum team of four. 

Formwork:
Formply

 


Technical issues:
A number cracks developed in the walls. This was only a problem because Sheldon wanted to leave the walls unrenderd internally.  The cracks were patched and covered with render in artistic whale and plant designs.

Advice/Recommendations:
Sheldon expected the hemp walls to have better sound insulation and expected the studio to be more sound proof than it is, but has found that the acoustics are good and the studio has a good feel.

Contact:
Builder, Nicholas Jouin
Nicholas.jouin@permastructure.com.au

Mullumbimby Hemp Studio

Rear view of studio


Location:
Mullumbimby, NSW North Coast

Type of Build:
Studio/extra bedroom, with bathroom and kitchenette

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:

Andrew undertook the studio project as owner builder and engaged carpenter Nicholas Jouin of Permastructure

Size:
32 m2studio plus mezzanine total 38m2

Cost:
$67,000 plus rendering and landscaping total est $75,000
Hemp materials cost $4,000 + $1,000 render

Date of construction:
August 2015 - December 2015

Purpose of Build:
To provide a flexible space that could operate as an extra bedroom to the main house or as self contained accommodation

Choice of Material:
The main house was built of hemp. Due to cost only one wall of the studio was built with hemp.
 

Hemp wall left unrendered

Climate:
Zone 2 - Warm humid summer, mild winter

Local Council:
Byron Shire Council

Obtaining Approval:
Approval was obtained at the same time as the main house, with a subsequent s96 variation of approval for the studio.  Building surveyor Dwane Roberts of DP Roberts Planning Solutions was engaged to assist with the approval of the main building.

Construction:
Andrew acted as owner builder and engaged carpenter Nicholas Jouin to do most of the construction work. The hemp wall was constructed during a workshop. Balanced Earth Building rendered the studio externally



Internal view

Footings:
Slab on ground. The slab for the studio was poured at the same time as the main house.

Floor:
Polished concrete, and timber on mezzanine

Frame:
Timber frame, 90 mm T2 termite treated pine, made on site

Walls:
200mm thick hemp wall using AHMC binder and hemp.  Rendered externally with AHMC render by Balanced Earth Building. The hemp wall has been left unrendered internally and will be finished with a breathable clear finish. The other walls are clad with corrugated Zincalume over Kingspan Aircell R2 insulation and plasterboard internally

Windows:
Aluminium framed, single glazed

Ceiling:
150mm Bondor Insulroof panels, the larger 150mm size was required because of the span

Roof:
Bondor Insulroof  panels providing R 3.53 and finished with corrugated Colorbond in shale grey (check insulation on 150)

Heating:
None

Cooling:
Ceiling fan

Wall construction:
A workshop was conducted by Klara Marosszeky from AHMC to build the walls. This was attended by Nicholas Joiun, four builders including those from Balanced Earth and three other participants.  The workshop was held over three days with one day of formwork and two days of hempcrete placement. (Do you know what type of mixer was used?)

Formwork:
Marine ply black seconds fixed to the framework with batten screws



External hemp wall rendered

Technical issues:
Ensure good communication with trades and contractors and confirm what has been agreed upon

Advice/Recommendations:
When engaging builders and trades get recommendations from and speak to other clients
Take care in contracts as to what is allowed for PC items

Contact:
Andrew Wadsworth

andrew@mullum.it

Nicholas Jouin
Permastructure

nicholas.jouin@permastructure.com.au

Balanced Earth Building

office@balancedearthbuilding.com
ph 0415 739 767

Note:
The hemp studio is available for rent on Air BNB

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