Roofconsult Website What Do a Horse And a Slate Have in Common? by Haroun El-Helw, SSQ Group
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As the horsemeat crisis was at its peak recently, I happened to be walking down the ready meal aisle of my local Tesco. It struck me how much trust we give to the people who sell our food.
We need to trust our supermarkets. They, in turn, need to trust their suppliers. They need to trust their manufacturers, and so on.
When this chain of assurance is broken, how can we really be sure of what is on our plates? Indeed, millions of consumers were told during February and March that, in place of the succulent beef shown on the boxes, they had actually been eating horse.
Looking at all those glossy photographs on packs of “beef” lasagnes, cottage pies and burgers stacked up in the supermarket’s fridges told me something else: appearance is simply not enough.
This is so true in our industry too. A roof made from slate that looked really good when it was installed, can fail within just a few years. And remember: “failure” ranges from ugly rusting that spoils the appearance of a building; to catastrophic holing of slates, or a complete discolouration and disintegration of the slate. This leads to the roof needing to be totally restripped and replaced. Picture 1
It’s an unpleasant and expensive way to find out that your product isn’t what you thought it was.
We must have good traceability because slate gets sourced from a quarry. A quarry typically covers a large area, across which you find rock of varying grades. You can take both ‘good’ and ‘bad’ slates from the same seam of rock.
This is completely normal. And under properly controlled conditions it allows companies to offer a product range for projects of a range of budgets and specifications.
But you get a big problem when a supplier fails to identify each grade clearly. This might happen deliberately or carelessly, but the upshot is the same: different specifications that are sold under the same brand name.
Qualifying for the ubiquitous ‘CE’ mark is easy. A quarry simply submits rock samples of its own choosing and sends them to be tested to the BS EN 12326 standard. If the samples don’t represent the quarry as a whole – unintentionally or otherwise – it can easily give a misleading result. A quarry given the highest possible classification of A1-T1-S1 could in theory be the source of slate that is of significantly lower quality. Picture 2
Certain regions deliver consistently high quality slate. Take the La Cabrera area of Spain from where we source Del Carmen and Matacouta, two of the world’s best quality slates. All of our slates are traceable to source, with Del Carmen also offering barcoded tracking and unique pallet numbers - one of the reasons it is tested to the world-leading slate standard NF 228, and passes with flying colours.
If you can be absolutely sure your slate comes from such an area, it’s a guarantee of resilience, durability and overall quality. But in variable areas, slates containing both reactive and non-reactive pyrite are being sourced. If the minimum quantity slate from one of these quarries has achieved the A1-T1-S1 classification, there is absolutely nothing to stop a quarry from achieving and marking all their products with it. You can see how this can lead to roof failures.
A reputable quarry such as Sarria, in Spain, wouldn’t risk damaging its long-term reputation of its stone with misleading markings, but it does happen. This can be exploited further along the supply chain, when customers offer their clients poorer grades of slate in place of the higher specs they actually need.
Traceability must be part of specification process; it’s simply not an optional extra. If you can guarantee where your slate comes from, it guarantees the performance and lifespan of the projects in which it is used. And ultimately you have an assurance that messy, reputation-damaging roof failures will not occur. Picture 3
Why ignore this in favour of choosing materials based purely on their price? It is a false economy, and the long-term costs, dwarf any short-term savings – a truth that the food industry is experiencing first hand.
If you wonder what I chose for dinner that day, I actually left the supermarket empty handed - I’d lost my appetite. Traceability makes, if you like, the difference between getting a fillet steak or ending up with horse meat on our plates.
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