I had a 40sqm indian sandstone patio laid a month ago, bradstone fossil buff slabs, by a method which I now understand to be spot-bedding. At the point were I realised the issues of 'hollowness' it was too late to rectify the whole patio although some individual slabs were taken up and relaid. The contractor has been paid off as I wanted a clean break although he says his work is warranted for a year.
My query is to do with moisture/staining effects that are now appearing on some of the slabs. I'm trying to throw some light on why this is happening and understand if the problem is transient and will disappear over time.
I suspect this is a case of live and learn by your mistakes but again it might be interesting to know what longevity the patio might have and what advice anyone would give to try and mitigate if there are any long standing problems that may develop. Many thanks. J ...
Ach thats a shame other than the spot bedding and a couple of cross joints it looks well done with neat pointing and cuts. The marks appearing relate directly to where the flag is and isn't supported by mortar and will never fully disappear. The unsupported areas can also be prone to going green very quickly due to miosture in the void beneath. If they were lifted and relaid properly the marks would disappear but thats unlikely to happen so you're best bet would be to wait and see if the winter frosts cause them to lift if they do then his warranty should cover it if they don't then it'll be ok but never great.
Pablo. I think you're right. In fairness the patio is no disaster far from it, slabs cut well, good brickwork, water drains to edge, neat pointing. It's such a shame though that the larger slabs were spot bedded. As you say, may be over-kill to pull every spot-bedded one up and simply wait until remedial action is required post the winter.
Is that efflorescense on the slabs? Was the sand used for laying orange/brown in colour? I've suffered this on Modak Rose and it washed off well with water and a stiff broom.
i concur with the above
someone has a nice eye, and its probably ignorance more than badness that has led him to spot bedding
the pointing looks good and this may bail you out medium to long term
LLL
