Concrete slabs

Hi there, We are currently in the design phase (with an architect) of our stone house here in Australia. We are very keen to be as natural as we can, but our council regulations are horrible. I am looking for advice about house bases. Although the house will be built on a very gentle slope, we have decided to have it on the ground with terraces leading down to it, rather than up on stumps. The last big issue we need to decide upon is the base. And in the end it just seems like the concrete slab is the best option - longevity, council regulations etc. The only other real option to us is to do an earth floor. This may be possible to get through council with a lot of mucking around. I love the idea, but don't really like the look of an earth floor as my final 'under foot' flooring. And even an earth floor will need to be under-lined with a waterproof membrane for council - and so there is still a disconnection with a full natural approach. And yet - something in me is repelled by using concrete. I guess we can go for the more enviro friendly brand etc. but it just isn't sitting right. Two eco-architect friends seem very positive about us using a concrete slab base though, so perhaps I am being ridiculous. Any advice/thoughts very welcome. Many thanks

Hi Victoria,
I am not an expert on earthen floors, but I do know that I have never seen them used as a foundation. The cement slab is a foundation for the walls. An earthen floor would go over or inside of some sort of foundation for the walls. That foundation could be a slab, posts, rubble trench, frost wall, etc.

***Edit - I missed this was your first post, so Welcome to Permies!

I also realized Australia probably wouldn't need a "frost" wall. That is just where they build a cement wall around the edges without anything in the middle.

Victoria,

You have several options:

1. Footings under the walls. Later you can put required membrane and either pour concrete floors (on which you can lay tiles, mosaic, stone, clay floor, etc.) or put some compacted base and then lay the flooring materials.

2. Footings under walls and floor slabs (10-20 cm thick) in between in one pour.

3. One massive slab of the same thickness under entire house.

They require the membrane so the house without a basement will not suck the moisture to the floors - either through concrete or directly through the dirt. Of course it could be excavated in such a way (with drains on perimeter) to avoid plastic, but they require it using the attitude "one fits all".

Thanks so much for your comments.

An earth floor can also be the foundation - it involves an engineer coming into the picture and working out the depth the earth needs to be compacted - but as was mentioned, it still needs some kind of membrane to prevent damp.

I really appreciate the feedback. I eco renovated my last house, and have a fair bit of knowledge about many aspects of a natural home, but this 'starting from a clean slate' is both wondrous and daunting! It is the first time I have had to consider things like 'footings'! But a full earth base and floor will certainly need maintenance and attention, and so the concrete wins out there.

I read back through some old threads on this site, and perhaps concrete is not quite the demon I had in my mind. And I think I will end up going for a complete concrete poured slab, that will also provide the footings for load bearing beams and the walls.

We are very aware that extensive planning in the design stage will lead to a forever home that has the most sustainable and least amounts of headaches down the track! However, in this crazy old world, we are also in a bit of a hurry to put a roof over our heads before things get worse and worse with the building industry and society in general!  

Thanks for the welcome - yes - just found this site. My partner and I are keen permaculturists, and are setting up a small community here in Victoria, Australia. We won't have extensive acreage, but are very excited about getting all our gardens up and running.

The climate here in Victoria is much more European style than other part of Australia. Our challenge is planning for a climate that can get incredibly hot on occasion in summer (although wildly oscillates) and although the winters are fairly mild by North American standards, we still get to freeing and just below on occasion too.

Our house is also planned to be completely electricity free. We are planning windmills to pump water up and earth tubes for air-con etc. And lots of emphasis on passive solar design too.

Thanks again

Wow! How is it gonna be completely electricity free?

Victoria, its good to hear of your efforts.
I am in Bendigo and encourage people to build no more than a 100 Msq home.
A 35 square home [ 350 sq M ] can never be sustainable because of the amount of energy to create and maintain them..
I have worked in the area of efficient homes for 50 years.
I would not work with an architect, I would suggest a good builder / designer in what you actually want.
Architects are often hopeless for homes with alternative materials.
Natural Building Australia may be a good starting point.
What are you actually planning to have?
What area are you in?

Victoria McKay wrote:I read back through some old threads on this site, and perhaps concrete is not quite the demon I had in my mind. And I think I will end up going for a complete concrete poured slab, that will also provide the footings for load bearing beams and the walls.

I am not familiar with the permitting landscape where you are. I permit various construction and equipment work across 7 states in the USA. We've done some very special things in historic houses and regular homes that were unconventional by todays standards.

The key to all of those projects was getting to the right person. A lot of permit techs apply the letter of the code and do consider the intent of the code. One project in a large us city took us 9 months to get a permit for. It was an 1860's home that ended up being 4 stories tall through additions over the years. It was on the historic registry. I had to work all the way through the building department to finally get to the city commissioner to obtain approval.

If you get the sense that you will encounter or have encountered someone who will consider the intent of what you are doing, you can be successful doing non conventional things. It can be a gamble. In a lot of cases it can be exacerbating and may not be worth the effort.

If the conventional concrete method is acceptable, that will be easiest to get through the process. However, I would not discourage you from trying if you feel it is important to try something non conventional. Someone needs to pave the way for others, sometimes.

***Side note. My experience with houses on the historic registry is that 100% of the homeowners I have personally dealt with would never have bought or registered the house if they really understood all of the restrictions and board approvals you encounter to make any changes***