Old Scots quarries could be saviour of flats

Geologists say that extensive research is needed on Victorian flats in the concentric zone about one mile from the city centre to find the exact stone required for renovation amid fears the buildings are turning back into sand.

Material being used to patch up the eroded masonry, much of which is being imported from the north of England, is not always a correct match as rock from different quarries contains varying clay content.

Problems with Edinburgh’s sandstone flats came to a head earlier this month when owners of property in one Bruntsfield common stair were each landed with a 47,000 repair bill. Some are now having to consider remortgaging their homes to meet the huge costs, which have reached a 6.5 billion crisis across Scotland.

The worst-hit areas in the capital are understood to be Marchmont, Gorgie, parts of Morningside, Abbeyhill and Leith. The masonry used for the tenements was cheaper than the high-quality Craigleith sandstone chosen for the New Town and was introduced to the city following the arrival of the canals and railways.

Alan McKinney, Scottish Stone Liaison Group chief executive, said most of the sandstone used for repairs now was from the same area in the north of England which did not always match the material in Edinburgh’s buildings.

"There is the assumption that all stones are the same when they are not. Often people look at the colour of the stone to see if it matches the building when it is actually the mineral content which is the most important thing.

"Sandstone absorbs and releases moisture. If you introduce a sandstone block with a higher clay content into an existing building then it is going to shed water to neighbouring stones which subsequently will need to be repaired again.

"That’s why it is crucially important to get it right."

Fewer than ten of the original 600 sandstone quarries in Scotland remain open. A Sainsbury’s supermarket now lies on top of the valuable Craigleith quarry which could have been used to repair buildings in the city’s New Town, which is a world heritage site.

But Dr Ewan Hyslop, British Geological Survey building stones expert, said there was a large seam of the high-grade sandstone at Cullaloe quarry near Burntisland in Fife.

"About 90 per cent of the sandstone used in Edinburgh now is from Northumberland and Yorkshire, which is not always the most appropriate material.

"We have come to a crossroads where the repairs need done but we don’t have the appropriate materials do to the patching up.

"The centre of Edinburgh is a world heritage site and therefore I believe it deserves to be fixed properly with the right stone.

"There are old quarries in Fife - which could be re-opened - which have stone that would match the New Town tenements. If we could find out which quarries supplied stone for the surrounding tenement areas in Edinburgh then we could repair them far more effectively, so that the buildings will last another 100 years."

Stirling firm Tradstocks Ltd has applied for planning permission to extract 42,000 tonnes of sandstone over 11 years from Cullaloe Quarry, which was last worked in the 1950s.

Peter Stewart, Tradstocks director, speaking in October, said: "Opening this quarry could be of potential national significance."

The problem in Bruntsfield was discovered when the council was called in to settle a dispute between the owners over roof repairs.

Across Scotland the news means that nearly 20,000 out of the 190,000 tenement flats that were built before 1919 are in need of major repairs.

The Scottish House Condition Survey looked at 30,000 properties and found that the repair bill for privately-owned homes was 5 billion, with council and housing association flats making up the rest.