Posted: Fri Jun 15, 2007 8:22 pm
A little bit of advice needed please.
We are in the process of having a Yorkstone patio laid. It is 600mm x 50mm by random length sawn slabs of "crossland hill" stone. The slabs have been laid on a whackered subbase, and then on a wet bed of sand and cement approx 40-50mm thick. We're waiting for the slabs to be pointed, but we've noticed that a few of the slabs have slight fissures at the edges, extending a few inchs into the slab, and which appear to run right through the full thickness of the stone.
We've raised this with the contractors and they've said that this is normal with yorkstone, and that the cracks won't get any worse.
We wondered whether anybody had ever come across this before, and can confirm a few cracks are normal. You can't see the cracks without looking specifically for them, and it was only after rain, while the slabs are drying out that we first noticed this problem. While possibly not too much of a problem in summer we are a bit worried about the cracks getting worse in winter with any water in fissures expanding.
We are also wondered whether there is any kind of quality grading for yorkstone - The stone was supplied by the contractors and seemed fine when it was delivered. We did check it but don't think we would have seen any fine hairline cracks at that stage, so we can't say whether they have been caused during the laying process or the fissures were there when the slabs were delivered. Is there a market in second quality or graded stone slabs? Are you aware of any websites that might deal with stone defects, and what is considered normal?
If you feel the stones shouldn't have slight fissures and we ask the contractors to replace them, then we are concerned that becasue the bedding layer is now dry this could disturb the other slabs - any advise on how to remove a damaged slab and relay without damaging the surrounding slabs? Do you think sealing the slabs might be an alternative to having them replaced?
Your comments would be much appreciated
regards
Moonman
We are in the process of having a Yorkstone patio laid. It is 600mm x 50mm by random length sawn slabs of "crossland hill" stone. The slabs have been laid on a whackered subbase, and then on a wet bed of sand and cement approx 40-50mm thick. We're waiting for the slabs to be pointed, but we've noticed that a few of the slabs have slight fissures at the edges, extending a few inchs into the slab, and which appear to run right through the full thickness of the stone.
We've raised this with the contractors and they've said that this is normal with yorkstone, and that the cracks won't get any worse.
We wondered whether anybody had ever come across this before, and can confirm a few cracks are normal. You can't see the cracks without looking specifically for them, and it was only after rain, while the slabs are drying out that we first noticed this problem. While possibly not too much of a problem in summer we are a bit worried about the cracks getting worse in winter with any water in fissures expanding.
We are also wondered whether there is any kind of quality grading for yorkstone - The stone was supplied by the contractors and seemed fine when it was delivered. We did check it but don't think we would have seen any fine hairline cracks at that stage, so we can't say whether they have been caused during the laying process or the fissures were there when the slabs were delivered. Is there a market in second quality or graded stone slabs? Are you aware of any websites that might deal with stone defects, and what is considered normal?
If you feel the stones shouldn't have slight fissures and we ask the contractors to replace them, then we are concerned that becasue the bedding layer is now dry this could disturb the other slabs - any advise on how to remove a damaged slab and relay without damaging the surrounding slabs? Do you think sealing the slabs might be an alternative to having them replaced?
Your comments would be much appreciated
regards
Moonman
