"You always kept something for another time because it could fix something else," he said.

Now based in Tharwa, the traditional bush craftsman is putting the lessons he learnt as a youngster to work at one of Canberra's most treasured heritage attractions.

Mr Gostelow is restoring a two-room slab shed that is believed to have been constructed in the 1880s beside Blundell's Cottage, a workers' dwelling that was built a few decades earlier on what later became the shores of Lake Burley Griffin.

As part of the $850,000 second stage of restorative works at Blundell's Cottage, Mr Gostelow will remove the slab shed's deteriorated walls, replace decayed footings and bases, install a new retaining wall using original stones, re-craft the windows and doors, and patch the internal lime crust flooring.

His task is to do it all while ensuring the shed remains true to its original build - a tough task given the shed is almost 150 years old.

"You have to put yourself in the position of the people that originally built it," Mr Gostelow said.

"There’s a resourcefulness and a common sense approach, and you see a fair bit of that in these sorts of buildings where they just used what they had and did the best they could with what they had at hand.

"Everything takes a lot more time than we see in the modern day. If you're going to do things traditionally, you do them how they would have done them back in the day, and that’s with hand tools."

National Capital Authority chief executive Sally Barnes said the level of care exercised by Mr Gostelow, one of only a handful of craftsmen still using bush skills in Australia, would ensure conservation of the site for generations to come.

“Once reopened, the slab shed and restored landscape will provide an historic insight into the lives of the many families who lived in the cottage from 1859 to the 1960s," Ms Barnes said.

"The slab building will be used to tell the story of the Blundell family, marking the first time that every era of cottage occupation will be represented in the overall display."

Blundell's Cottage, built in the 1860s, was home to tenant workers on the Duntroon Estate, with enough room to maintain farm animals and grow crops for produce.

Just three families lived in the cottage during the century it was privately owned. It was to be demolished in 1962 in preparation for Lake Burley Griffin, but instead became a museum operated by the National Capital Authority.

The second stage of restorative works on the site also includes enhancements to the cottage's landscape setting and new interpretive elements that will help better reference its agricultural heritage.

“These new works will interpret past activities, including re-establishing a vegetable patch to reflect Alice Oldfield’s kitchen garden, as well as creating an interpretive walk following the original fence line,” Ms Barnes said.

“We will remain respectful of the cottage’s past by incorporating traditional materials for the landscaping using local timber, gravel and stone."

Blundell's Cottage is closed during the restoration works, and is expected to reopen in August.