Concrete or stones around house with clay soil.

Originally Posted by JB1

Hi,

The house I'm building is on reactive clay soil. The foundation bordering the house has 450mm x minimum of 2000mm deep piers every 1.5m.

I think the whole house has been well over engineered from the footings to the steel beams (every tradie who has seen the plans has been surprised how over engineered it is). I'm not complaining too much as IMO it's better than under-engineering it.

I like the look of stones with concrete pavers around the house and I will install agri drain so water doesn't pool or stagnant around the house.

I'm wondering due to my soil type and to protect the house, are stones walkway around the house a bad idea?

Or is it a much better idea to concrete a 1m border along the house?

Once of the biggest problems with clay soils is their saturation and later drying out which cause the movement. Stones provide a mulching layer that reduces drying and allows moisture to pass through. Depending on the situation they should retard evaporation loss and minimise excessive drying. If anything stones should give a more stable outcome, I'm not sure I would be to keen on concrete all round as this most likely will reduce recharging of the clay during winter however i'm sure others will have a view.

Thanks for a replies.

A lot of think about.

Johning- Footing/Engineering design does not mention any impermeable border that is required.

I'll chase up the engineer who designed my house, but he's on leave at the moment.

It would be nice not to be have concrete all the way around the perimeter- from an aesthetic view.

I'm going through a similar situation at the moment. I found tree roots under the house while restumping and worms in the dirt under the verandah. I thought of all sorts of ways to combat the mousture under the house ( the house did have a drain arround it but only about 100mm deep). The builder who is undertaking the work I can't do was/ is adamant, if I didn't want mousture under my house I needed a concrete barrier and in my case it's got to be dug down to rotton rock which is about 500 to 600mm deep on average. The cost will be approx. $1600- and from a resale point of view worth every cent.

Rock is approx 2500mm deep.

I spoke to my engineer.

He said it doesn't need concrete as long as the natural ground level is more than 150mm below the slab.

It's ~150mm now, but by the time I dig the ground for an agi drain (and cover with stone) the clay will be at least 300mm lower.

But note that I have deep piers surrounding my house.


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