Sarjeant Gallery redevelopment: Visible milestone for restoration project

Under the canvas tent on the Sarjeant Gallery roof. Photo / Barry Robin, McMillan & Lockwood

Restoration work is now happening under a massive protective tent over the Sarjeant Gallery and its iconic dome can be restored and cleaned.

The 103-year-old building in the Whanganui town centre has to be handled with particular, specialist care to ensure the safety and structural integrity of the old building and protect its fragile features, foundations and masonry walls.

The redevelopment project involves earthquake strengthening and constructing a new wing – Pataka o Sir Te Atawhai Archie John Taiaroa – named in honour of the much-loved Whanganui kaumātua. The new wing will house the Sarjeant Collection, new gallery and event spaces, a cafe, shop and offices.

Working to install the canvas tent over the Sarjeant Gallery roof to enable all-weather work during the next year. Photo / Supplied

While the tent is in position during the next 12 months, the Sarjeant Gallery's century-old neoclassical dome will be restored to as close a condition as when new. It's mainly made from concrete and panels of glass with decorative plaster on the exterior. The dome won't be removed or disconnected from the roof at any point, but will be strengthened using a concrete collar.

Redevelopment video #11 - April 2022 - Erecting the roof tent over the Sarjeant Gallery from Sarjeant Gallery on Vimeo.

When finished, the dome will appear the same and the collar will be covered by decorative plaster. Once the restoration work is complete and the dome has been thoroughly cleaned, a protective membrane will be applied to the concrete and plaster surfaces.

The team involved in its restoration was pleased to find the inside of the dome is in good condition with no damage to the glass panels and just a light clean and paint is needed.

In late 2021 and early 2022 a specialist team worked with McMillan & Lockwood to plan the complex installation of the enormous tent framing system and the fitting of its durable and heavy canvas cover.

Sixteen trusses were placed by crane over the Sarjeant Gallery roof as the canvas tent structure. Photo / Supplied

The safety of people working around and within the project is always a key priority and the roof tent staff worked to all safety protocols on-site and had the additional consideration of working at heights, which required the use of harnesses.

The tent will prevent water getting into the building while a concrete diaphragm is built to encircle and span the whole roof, supporting the old walls and the seismic-strengthening vertical steel strands.

The structure that frames the tent has 16 triangular metal trusses over the gallery. They were lowered into place individually by a huge crane that reached up to 200 metres high. On the day of installation the team needed to wait for the wind speed to drop but managed to get all the trusses lifted into place by day's end.

Under the canvas tent on the Sarjeant Gallery roof. Photo / Barry Robin, McMillan & Lockwood

Construction tents are commonly used to allow contractors all-weather access to the site and complete sensitive work without being subject to the effects of weather. The construction tent also allows tighter quality controls in protecting the existing structure.

Despite several unavoidable delays since construction started in late 2019 - particularly with Covid-19 affecting on-site work and related resourcing - the various specialist teams involved in the project are making steady progress.

• Gaye Batty is the project director for the Sarjeant Gallery redevelopment.