slab cast on fill or suspended?

[ooox]

I'm involved in a project where a debate has sparked off on whether we should be cast a ground floor suspended slab on built up grade or using a profiled metal decking on block walls.

The FFL is sitting approximately 1500mm above natural ground levels, and one proposal is to use site won material retained, compacted etc to bring up the levels for a piling and footing system. The other option is to pile, cast the footings and bring up the levels using concrete blocks and supporting profiled metal decking. Just trying to gauge other peoples experience here as both options have their inherent disadvantages & advantages. Any thoughts or recommendations would be appreciated. Builder is still to be appointed....

 

[rowingengineer]

I like the idea of suspended slab, but would want more info before I gave the metal deck the tick. Genrally my change over point is about 1.0m of fill on poor soil, if good soil below this moves to 1.5m



An expert is a man who has made all the mistakes which can be made in a very narrow field

 

[civeng80]

I think in a case like I would go for the cheapest proposal.

A gut feeling (and I did something like this about 3 years ago) would be slab on fill still designed as a suspended slab.

 

[BAretired]

Hollow core slabs on bearing walls may be worth considering. The economics vary according to location and market conditions.

BA

 

[Zambo]

Is there a reason why FFL is 1,500mm above ground level? Your building gorund floor slab will presumambly have to tie in with a carpark or landscaped area so it seems a big difference. In many cases it can work that the underside of the floor slab is not so different to the natural levels so the suspended slab using the esxisting soil is a cost effective option. If you have to bring in a large quantity of fill probably a falsework system would be cheaper.