Finishing touches are being made to a temporary structure built to protect Tyntesfield House from the elements.

The giant scaffold, which is thought to be the biggest freestanding temporary roof structure in Britain, envelopes the Grade 1* listed house while essential repairs take place.

Measuring 55m wide and 22m high the temporary roof will protect the historic house as multi-million pound restoration work by the National Trust continues.

Tim Cambourne, senior buildings surveyor said: "The age and fragility of the building means that it can't take any of the weight of the scaffold. It's been specially designed to take the load away from the building and into the ground surrounding it, hence the reason why it's so wide.

"The up-side to having all this scaffold is that, as well as allowing us to make essential repairs, visitors can now take in previously unseen areas up at roof level and can get right up close to the rooftops and chimney pots."

At the last count, 28 miles of scaffold poles, 11 miles of scaffold planks and over 24,000 fittings had been used to create the extraordinary maze of criss-crossing metal which now surrounds the house.

Chris Rogers from SGB Project Services who designed the scaffolding said: "It's one of the biggest freestanding temporary roof structures in Britain and was quite an engineering challenge – it literally hugs the building without putting any pressure on it. We also had to incorporate walkways and access points for the public to view the work as it progresses.

"The scaffold holds up a huge temporary roof which keeps the house dry while the tiles are replaced. We basically shrink wrapped the scaffolding using plastic sheeting which we bond together to create a weatherproof surface."

Tyntesfield is holding a Meet the Builders Day on Sunday from 11am to 4pm. The house is open until November 1 and reopens 20 March 2010.

For more information contact 01275 461900 or e-mail Tyntesfield@nationaltrust.org.uk.