The Brew Cabin

Posted: **Fri Mar 30, 2007 11:02 am**

I could do with a bit of advice please.
A paving contractor has laid 15-20mm thick indian sandstone on a full bed wet mix with butt joints filled with kiln dried sand, looks good and has got his levels right. unfortunatly a couple of problems have occured within 2 weeks of finishing
Firstly all the sand has washed out, is this normal I was told it would harden off with moisture.
And secondly after rain, water pushes up from the joints when you walk on the slabs indicating water is under the slabs is this normal?
I have since been told that indian sandstone of this thickness (thinness!) MUST be pointed to bring extra strength to the patio/path as sand joints will lead to cracking and movement - is this correct?

thanks

Posted: **Fri Mar 30, 2007 11:10 am**

Kiln-dried sand is for Block Paving. This type of flagstone MUST be mortar pointed. KD sand does not "harden off". It's sand, pure and simple.

Posted: **Fri Mar 30, 2007 11:18 am**

Thanks for your reply Tony.
Is it right to assume that the slabs should be 'stuck' to the morter bed and not just sat on it,

Posted: **Fri Mar 30, 2007 12:52 pm**

It's not absolutely essential for the flags to be bonded to the laying material - think of flags laid onto sand, f'rinstance. However, as you state the contractor laid onto a wet mix, I would have expected the flags to be well and truly held fast.

Posted: **Sat Mar 31, 2007 5:12 pm**

I'm guessing that if he's KD'd it the joints are very small, too small in fact for pointing with mortar. This is a major problem as LLL says KD sand is for jointing block paving and other paving designed to be butted together. The water coming up comment is baffling though ... this suggests the slab moves down when you tred on it?

Posted: **Sat Mar 31, 2007 5:23 pm**

Best course of action is to pressure wash all the sand out, let the patio dry and sweep in romex. This will set hard and should hopefully do the job

Posted: **Sat Mar 31, 2007 6:49 pm**

Out of interest - any idea how much Romex would be required for a 30m2 patio?

Posted: **Sat Mar 31, 2007 7:28 pm**

5 tins approx dave,dan and my good self used rompox which for me anyway is still looking good (used a tin this morning on a path which comprised 17 @900 by 600 injun stones
i have used KD on a patio with tight joints and the people love it
once a year they jet wash the whole lot ,let it dry and re brush a new bag of KD,each to their own
LLL

The Brew Cabin

Indian sandstone - Kiln dried sand joints