Firstly, I've been using the main site for general tips, tricks & advice for a while now and it's always been a great source of reliable information. It's helped to get me out of a pinch more than once that's for sure, so thank you!
I've never had to post directly here as usually the main site can answer my questions but on this occasion, I wasn't able to find anything.
So I've recently laid a patio for a client using Kandla Grey Sawn & Honed Sandstone 600X600 provided by nustone. It seems that water is being held on the edges of the patio but I can't work out why?
The patio hasn't been grouted yet but I didn't think this could be the cause of the problem?
I initially thought that this may be an issue with the gradient of the patio, however, after reading through the post about gradients it seems that all is well?
Patio is 3m X 7.2m and raised 30mm at the start of the patio.
Looking at the picture I guess that the slabs are draining to the right as I’m looking at it? That would mean a fall of 1:80 over 3 m ? 300\80 = 3.75 cm fall on the 3m length.
Sometimes the slabs will have very small lips to the edges, this can catch the last of the moisture as it drains off the slab which looks like your pic.
The hole cut around the recess tray may look good, and is certainly a credit to your skill with the saw, but it's out of standard. That slender 'edge' nearest the camera is just gagging to fracture! Any cut that results in more than one quarter of the flag being removed has to be cut in such a way that relieves internal stresses within the flag. The esiaest way to achieve that in your scenario is to extend the cut lines for the tray edges so that the flag is sectioned into four long, rectangular pieces.
Pedantic, I know - but these Standards are written for sound reasoning. If you client prefers it that way, you can indemnify yourself by getting them to 'sign off' that methodology - in effect, a written statement to the effect that they were informed that such a cut was out of standard but they prefer it that way and are quite happy to accept the risk.
Bloody good saw skills, though!
Anyway - the hanging water mystery. I've seen this before with some honed sandstones and it seems to be, as MikeG suggests, the slightest of lips right at the arris of the flags. Could you place a shorter spirit level or steel straightedge across the flag to check for any hint of 'bowing' - can you see daylight beneath the straightedge?
I'm really not 100% sure how this is happening. There's nothing obvious about the *standard* honing process that would cause this, and it does seem to affect only certain suppliers, so I've been suspecting individual producers are doing something slightly different in their seconmdary processing routine. Are they, for example, honing individual flags bu hand after they've benn cut, and the oiperatives are focussing too much of the centre and skimping on the edges? I'd have to watch and monitor production to be sure, and as I'm nowhere near well enough to hang around in a dusty factory in Rajasthan for a couple of days, that's unlikely to happen any time soon.
If you find the flags are not perfectly flat, you could call on the supplier to replace, but the easiest 'fix' for future installations is not to skimp on the fall.
Thanks a lot, Mike & Tony, very helpful! I will certainly take on board your advice about the cutting, I'm not sure why I hadn't already thought about this before, to be honest! Haha!
Very sound advises all-round, much-appreciated gents.
Would you object to me using your photie as an example on that page? I thought I might show it as it is and then show a version that's been through PotatoShop to show how it should be done. I'll keep your name out of it, but provide a credit elsewhere on the page along the lines of "Some imagery provided by xxxxx"
