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The concrete slab thickness I requested is different to what I got: What should I do? PDF Print E-mail
Monday, 11 June 2012


Our latest building problem enquiry comes from a reader who is disappointed that he didn't get what he asked for and thought he had paid for when having a concrete slab laid.

"I'm having a problem with a slab that was erected by a reputable company. I was quoted for a 255mm thickness slab and now when the slab is finished being erected, I found out that the slab is 170mm. The weather-step is 60mm & the balcony is 120mm. The contractor says he has done it according to the engineer's design. I'm really disappointed as I wanted a 255mm slab. Monies have all been paid in. I would really appreciate your advice."

Les has advised this reader as follows:-

Thank you for your enquiry.

The difficulty that you have is that the job is done. I am assuming that, given the thickness of  the slab, it is cast as a solid slab (not pre-fabricated).  If the slab was designed as a 255mm slab and constructed as a 170mm then there would be a design problem. If you have paid for a 225mm slab then there should be a fair saving for you because much less concrete would have been used.

There is always a possibility that if nothing has been built above the slab that an extra topping in a lightweight concrete could be added but this decision would depend on the engineer. If the architect's drawings show a 255mm thick slab and the contractor has done something different then you have every right to insist that he builds what is on the drawing. The fact that your engineer designed a different thickness slab to what was shown on the drawing is an issue that you would need to take up with the engineer. It may also be that your architect issued a variation instruction for the slab thickness to be reduced which you would need to check on.

The bottom line is that you should be getting what you paid for or be entitled to a discount.

I hope that this helps.

Kind regards,
Les Abbott
Technical and Marketing.

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