Owner Building a Strawbale House
Here is a condensed form of what we have done and how it is layed out. You can also read the original notes we wrote.
There are general themes for the construction of all our buildings. They are: a monolithic concrete slab; steel frame; straw bale infill; and a colourbond corrugated skillion (single pitch 8 degree) roof. The standard "module" is 7.3 x12.15 metres (outside of walls, equates to 6.35 by 11.2 metres internally).
We are building a single bedroom house, a two bedroom "pavilion" and a workshop. Originally we had plans for a studio for Liz, but this has been dropped to save on escalating costs (who knows, we may save enough to get it back on track).
There are some general guidelines for design and construction of all buildings. They are: no stairs; passive solar; no outgassing materials (plastic, glue, lamminates, etc).
The steel frame was engineered to suite our house design, with webbed trusses spanning 10 metres for the workshop (same truss but shorter for the 7 odd metre spans elsewhere), and the trusses supported by similar webbed frames, about 5 metres apart. The largish span and especially the building design (which forced us to use 5 metres between uprights) may have cost us more than we expected.
The house has an attached carport (which could be walled in some day to provide more internal space); an almost external laundry and cool store room; an open-plan kitchen/dinning/lounge room that is open to a study, then a small corridor leads to the bathroom and master bedroom. The house is U shaped, to suit the contours of the site - a long, north facing, house would not fit unless we stepped it over the existing contours.
Front of Model House - This is a model we constructed to see if the thick walls and overall design worked. The view is from the north, looking into the open plan kitchen/dinning/lounge (centre section of house), with the large glass sliding doors on the left (for the study, with bathroom and master bedroom behind) and an open outdoor sitting area on the right (with the laundry, cool store, and carport behind).
Rear of Model House - shows the courtyard at the rear of the house, which will be filled with cool, shadey plants, and will provide a source of cool air for summer cooling.
The cool store room is a well insulated room, with a roof vent (to let out the warm air, hence creatign a chimney effect through the room) and a floor outlet from a buried pipe, which cools external air by passing it through the buried pipe before it enters the room.
For us this building provides Liz with some studio space (to make up for the currently dropped studio building); plus to provide spare bed space for visitors. To future owners of the property this makes the home equivalent to three bedrooms. We utilise a similar bathroom design to the main house, but slightly modified it (to save money).
20 by 10 metres in size (big). An encolsed room (noise protection) for an air compressor and a dust extractor - and the room uses a pipe buried on the south side of the shed to provide earth-cooled air (using a release vent high in the wall of the room). A large north facing wall of glass should provide great views and winter warmth.
The steel frame is made up from 65x65mm Square Hollow Section (SHS) as the main lengths with 25x25mm SHS webbing, using about a 30degree angle for the webbing. The plates at the bottom of the columns are 10mm thick, and either 150x300mm or 300x300mm, drilled for chem-set bolts into the concrete slab. The trusses are welded on top of the columns (once the columns have been roughly bolted into place). On the trusses are welded cleats (75*100 8mm plates with two holes in them) which are used to bolt the purlins onto. Over the purlins go es the roof safety mesh, fibreglass foil-backed insulation blanket, and roofing iron (screwed down to the purlins with self-drilling, self-tapping bolts).
Diagonal bracing (roof and wall) is provided mostly by diagonal rods. These are solid rods (M16 or M12 depending on engineering) with laps of 30 diameters (so 360mm for M12 rod) and the ends are all-thread rod (to tension the rod). The frame connects to the rod with a "radial washer" which is really just a cast iron hemi-circle with a slot/groove in it to allow the rod to go through the washer at almost any angle. The radial washer is designed to be held into a large slot in a steel plate, but we ground the little lug off and welded it to steel plate with a largish round hole (easy to manufacture on site).
A lot of diagonal bracing is provided by the webbed trusses and columns acting together, so some areas (where diagonal rod would interfere with the design - large windows) are braced by extra trusses and "L" sectioned columns.
We have 50 acres, and creek access for stock & domestic use. The block faces north, sloping down from the southern entrance to the northern creek. The property runs down a ridgline, with a drop of around 110 metres fromt eh entrance to the creek.
We will have some 800 square metres of roof space to collect water, flowing downhill to the lower collection tank (130K litres), pumped from there to our header tank (30 metres of head, 70K Litres). We have a 45K litre tank which will be fed via a Glockmann ram pump from the creek (as a store for stock and garden use).
Currently no grey water re-use, but plans include space & plumbing to add it later. We have an Aqua Claris sewerage unit, which is a wet composting system usilising liquid pumps to airate the sewerage, and worms to break down the solids, before being pumped into standard absorption trenches.
Access road as complete loop around house, acting as a fire break. Complete loop of 50mm polypipe (buried, with galvanised steel risers and brass taps) near the ring-road. The 45K litre tank has a 10K litre reserve with a fire fighting fitting. Little external wood in any construction. grash and low shrubs near the buildings, trees a distance away.
Average 800mm of rain per year; strong (<100Km/h) westerly winds (generally exposed to strong winds all round); some frost; moderating sea breeze (about 30 minutes inland from the sea by car); temperature range roughly -5 to 35 degrees celsius.