# Forum Home Renovation Structural Renovation  How much weight can a concrete slab support?

## reubs80

Hi there, 
Can anyone tell me what the minimum and maximum
weight per square metre that a suspended concrete slab must be able to
support in accordance with NSW building codes? 
I have an 8 yr old townhouse and would like to purchase an outdoor spa for the side courtyard, however I'm conscious that beneath the slab of the strata complex is the underground carpark and I want to make sure the slab can handle the weight. 
I'm aware there are many factors that determine the overall strength of a slab, however I assume there must be a minimum weight bearing standard for any new residential development.  
The dimensions of the spa are 2m x 2m with a total filled weight of approx 1500kg. 
Thanks,

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## rod1949

Go see a Structural Engineer and he'll probably want to see the structural/construction drawings and carry out an onsite inspection.  It may cost a few bob but if you don't seek professional advise and the slab breaks or cracks due to the spar then you'll be up for lots of bob's.

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## Master Splinter

Have a look around the building, especially in the service areas - there's often a Floor Loading plate with just that sort of information on it - point and distributed loads.

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## Pulse

1.5kPa for internal floors, 2kPa for decks over 1m is what the AS loading code says. 
Cheers
Pulse

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## bricks

Most elevated slabs built these days can not take the weight of a spa.
I've done heaps of spa's, pools, and r/w tanks in elevated buildings 1 storey to 22 storey around adelaide. 
From Experience most slabs are going to end up with a load capability of around 500kgs per square meter your spa is just over this. 
Get an engineer to investigate cost of around $800-00, some spa places will have engineers you can enguage.

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## commodorenut

How much does the spa weigh empty? 
1.5T of water, plus say 300kg (being generous here) for an empty spa would be 1800kg, over the 4 sq metres it works out to 450kg/m2.

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## Bloss

> Go see a Structural Engineer and he'll probably want to see the structural/construction drawings and carry out an onsite inspection.  It may cost a few bob but if you don't seek professional advise and the slab breaks or cracks due to the spar then you'll be up for lots of bob's.

   :What he said:  This is not one where advice here can be anything but indicative.

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## greenhj

How many people can fit in this spa because that will matter also.

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## DvdHntr

This will depend on the original design of the slab. 
It is a suspended slab for a courtyard/roof over a car parking garage. 
AS1170.1 has imposed action (live loading) tables for distributed actions. 
It would depend on the intended use but it could be deemed as 2.0kPa for general areas (residential) up to subjected to wheeled access 5.0kPa. 
The best bet is to try and contact the original engineer for the structural drawings.

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