Historic Scotland has announced that Smailholm Tower in the Scottish Borders has received a coveted five-star visitor attraction award from VisitScotland.

This means this remote but spectacular tower joins some of Scotland’s biggest attractions such as Edinburgh and Stirling castles in guaranteeing an outstanding, first-class visitor experience.

However, it seems it is not just within the realms of customer service that Smailholm is reaching new heights. Historic Scotland conservation experts are embarking on an ambitious project to waterproof part of the medieval roof using turf and sedum plants.

The existing outer finish to the roof was put on after the tower came into state care in 1950 in place of the long-vanished stone slabbed roof. As there was no firm evidence for how the original roof was constructed, this 20th century finish was seen as a neutral solution. However, hairline cracks have started to appear in the modern cement mortar and this may be the reason why water has begun to penetrate the tower. This has raised concerns for the timber structural elements of the property and the exhibition of costume dolls and tapestries inspired by Sir Walter Scott. Historic Scotland was concerned to find a solution before these items were put at risk. The solution being trialled at the moment is called soft topping and involves placing turf and sedum on top of a clay waterproofing layer.

Peter Ranson, Historic Scotland District Architect, said: “This is a challenging, practical experiment to discover the most effective way to waterproof the roof. Soft topping is quite widely used on roofs with gentler pitches, because it is an effective and natural way to soak up the rain, but as far as we know this is the first time it has been tried on one so steep. It may also be the first time it has been tried on a tower house and, with Smailholm, it is especially challenging as it is exposed to such harsh weather.”

If the year-long experiment is a success then consideration will be given to using turf or sedum across the entire roof.