Hi there people. I've just found this site and find it very interesting as I want to build a house soon.
I have some questions and would be pleased to hear some opinions.
The land is a few acres inland from Bunbury WA (about 33.5 ° south) so it experiences a high diurnal temperature variation. Summers are getting humid now as the monsoon creeps further south each year, and winter minimums are rising. Staying cool in summer is of more importance to me as warmth is easier and cheaper to get than 'coolth'. Jumpers and beanies are good things and any temperature over 17-18° inside is enough in winter.
I'm a sparky and have built a couple of weatherboards already - hot in summer and cold in winter as they have no mass, but were easy and cheap to build for a newby. I've looked at a lot of other houses too - some appalling, and some fairly good for overall comfort. The good ones tend to have a lot of mass.
My ideas at the moment are based on a mass-on-the-inside and insulation-on-the-outside approach for thermal stability using steel/polystyrene/steel panels ('coolroom'-type panels) externally on walls and as the roof -they have excellent spanning ability when thick.
Mass is still a question - a slab on sand is easiest, but hard underfoot compared to a timber or other suspended floor, so I've been thinking about a concept using an internal spine of rammed earth with rammed internal walls around the perimeter for an RBV effect. Trouble is I want a 2.7m ceiling height making the walls over 3m high which is dearer per m² than under 3m high.
An alternative to rammed earth is clay brick rendered with sand/cement mix, or that covered with plaster (not plasterboard).
My feeling is that a slab will drain heat out of the house in winter but that might be a good thing in summer. Maybe it will have a slab and massive internal walls.
So I've been wondering about these things -
Does hardwall plaster on bricks reduce the thermal stability / heat transfer of the bricks ? Posts here suggest not.
What is an 'ideal' ratio of mass to internal volume ? Posters here have suggested a figure per m² of floor area which is much the same thing.
Is a rammed earth wall generally more expensive than a rendered single-leaf brick wall ?
What is better for internal mass - rammed earth or brick ?
I don't really like the idea of a glassy north wall (glary, expensive etc.) so plan to use moderately-sized double glazed windows in all walls to reduce heat gain in summer. I'm guessing that double-glazing doesn't allow heat in to heat a slab or interior.
The house will be a smallish - 135 m² plus verandahs - rectangle as there'll be just me in it, and to keep costs down. I don't really care if it looks 'pretty' or not - function is more important. There will be a slow-combustion stove for cooking, water heating, and space heating, and I may incorporate hydronic piping in the slab if there is one. The fridge will contribute some winter heating as well.
The house I'm in at the moment is a 70's double brick with rendered brick internal walls and suspended jarrah flooring and it works remarkably well in terms of temperature stability. It has very little heat gain through windows in winter and marginal ceiling insulation, and isn't too bad in summer.
Thanks for any replies.
