Sunday, April 26, 2009

A Mudbrick Adventure

We promised to do this post about our house design way back in October last year. (Recently Geoff from Flood Street Farmlet - reminded us about this.) It's a convoluted tale so we will start at the beginning and spend the next few posts filling in details.
We spent several years pondering our house design and considered a wide range of materials and housing styles, ranging from the traditional Australian homestead with verandas all round, through to concrete earth-covered domes. To help us clarify our ideas, we spent about 12 months going on every alternative house tour we could find. This was a great way to explore possibilities. During this period we drew up the following criteria that we wanted our house to meet.
· Maximise our involvement by being owner builders to save costs and to maintain “ownership” of the process
· East-west alignment with large north facing windows to maximise solar gain
· Smaller windows on South, west and east to minimise heat loss
· Minimise fire risk by giving the house a low profile and by using low risk materials
· Eaves to exclude summer sun but allow winter sun to warm house and protect mudbricks from weather.
· Utilise at least some earth covered wall construction (a carryover from our earlier thoughts of building an earth sheltered house)
· Use thermal mass to maintain constant pleasant temperature (20 –25 degrees) and minimise energy use.
· Utilise natural ventilation and cooling pipes (stack and cross ventilation)
· Maximise natural lighting to all rooms avoiding need for lights during daylight hours
· Wet areas to be in close proximity to HWS to minimise hot water pipe distances
· Incorporate a window outlook that provides views of our bush environment
· Accommodate wheelchair access to most of house
· Plan to include provision for large concrete water tank, wood stove and wood heater
· Access between garage, pantry and rest of house
· Cathedral ceilings and exposed beams
· House to have appearance of being part of the environment- not alien to it
· Rooms to be reasonably spacious and Incorporate plenty of storage space
· Use plantation timber (not old growth forests)
· Minimise “wasted” space eg. halls
· Use materials with a low “embodied energy component”
· Adequate insulation using natural non toxic materials
· Use physical termite barriers- no poisons
· House plan to incorporate 3 bedrooms, a study/office/spare room, lounge, family room, kitchen, walk-in pantry, bathroom, toilet, laundry and garage/workshop.
· Deciduous vine covered pergola along northern wall for shade in summer but light in winter

Our solution was a mudbrick house (external and internal mudbrick walls), built on a slab with one earth sheltered wall (built with “normal” fired bricks and back filled with soil). The house and garage area is around 25 squares. A clerestory is used to bring light into the back of the house. We are very happy with the design we came up with, which meets 99% of our initial criteria.

We decided on mudbrick because:-
· They have low embodied energy
· We were planning to make the mudbricks ourselves. After we had made 80 bricks (out of the 4000 we needed) we decided to buy the rest from Barclay Bricks in Hurstbridge. Back in 1999, puddled clay bricks were only $1.65 each delivered- a very reasonable price we thought.
· They do not require great skill to lay. Slight irregularities in levels add to the “rustic charm”. We use this excuse all the time to explain imperfect lines etc.
· They have good thermal mass (but not good insulation)
· We love the texture of mudbrick wall surfaces
· Laying a few bricks puts the wall up a fair bit because of their large size
· They are fire reistant
· The density of the mudbrick adds an element of sound reduction so that activities in one room have less impact on people in another room
· By building a post and beam frame and later filling in the walls with mudbrick we could put the roof up first and then work on the walls under cover in rain, hail or shine.

In the next post we will get into the nitty gritty of construction and layout.

1 comment:

Geoff said...

Fantastic! Thankyou very much for sharing this with us. I'm impressed that you managed to cover 99% of your initial requirements, you've obviously put a lot of thought and effort into the design stage.

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