Historic Scotland will begin investigative work aimed at preserving two of Orkney’s best-known archaeological sites next month.
On July 11, a reflective film is to be fitted around the glass “roof” of House Seven, the best preserved structure in Skara Brae, in an effort to control a build up of heat inside the Neolithic dwelling.
Scientific monitoring has shown that the glass roof, installed in the 1920s, could cause heat gain in the summer. It also revealed that there has been minor structural movement, which could be due to the weight of the roof.
The project is a year-long experiment attempting to prevent temperature changes in the structure – changes which can result in moisture being sucked in and out of the walls, potentially damaging the ancient stonework and delicate carvings.
Meanwhile, a series of small test trenches will be dug on the top of Maeshowe on July 20. The work is to see whether moisture is leaking in where a Victorian roof and early 20th century concrete cap cover a hole left by Viking treasure hunters.
Monitoring work at the 5,000-year-old chambered cairn has largely shown it to be structurally stable, but did indicate that moisture may be getting in from the top. How to solve the problem will be decided once the results have been examined.
The monitoring at Maeshowe also confirmed that visitors are not causing moisture problems, which now means that visitor numbers will not need to be further restricted.
Results from the test trenches at Maeshowe are expected to take around a fortnight to analyse.
The operation at Skara Brae is expected to take four days and the one at Maeshowe should be completed in around five hours, with all the trenches being immediately back filled.
Stephen Watt, Historic Scotland district architect, said: “The operations at Skara Brae and Maeshowe are both designed to help us protect very important parts of our heritage from harm so they can be enjoyed by future generations.”