The $1.26 million seismic upgrade of Diocesan School for Girls' old chapel will be finished around mid-May.
School principal Heather McRae and business and planning director Merle Boniface said Aspec Construction's work on the Chapel of Our Glorified Lord was creating a building up to the same standards as new structures or 100 per cent of the building code.
The chapel, joined to the smaller wooden historic category 2 St Barnabas' Chapel which was moved to the school site from Parnell, was two skins of brick wall with an interior and exterior plastered finish.
Buildings like this are considered high earthquake risks.
The unreinforced masonry structure with a timber interior roof was build in 1922. Weak brick walls have been strengthened and tied into the roof and floor structures.
Tension cables have been installed into the chapel's columns and other columns have been rebuilt in reinforced concrete.
The upgraded columns have been secured to each other across the width of the chapel with steel beams inserted beneath the floor. Steel plates are being used to secure the roof structure to the walls.
A structural plaster is being applied to brick surfaces and recessing steel beams are being embedded into the brickwork. Plywood has been fixed beneath the roof to further strengthen the structure.
Heather McRae and Merle Boniface said the challenge had been to ensure the chapel's appearance was unchanged when the job was done so all new structures had to be concealed and the heritage character of the chapel maintained. Slate roof tiles have been imported from Wales to match the original tiles.
Masonry parapets were found to be weaker than initially thought and required more significant reconstruction work and the job is costing about $300,000 more than the initial budget. The school worked with heritage architect Dave Pearson on the project, which began in December.
Heather McRae said that in the past 18 years, the school had spent more than $70 million on 16 new construction projects. Much of the campus has been redeveloped and soon, work will begin work on a new three-level arts centre near the chapel, in the middle of the school grounds.
That will have a 1000-seat auditorium, teaching areas, acoustically designed spaces for music ensembles and visual arts facilities.
Merle Boniface said required carparks were already in the 230-space turf/carpark development.
$70m+ DIO Jobs
16 jobs in past 18 years include:
* Centennial Building Aquatic Centre
* Turf/230-space carpark building
* Junior School
* Science Building
* Shrewsbury extension
Diocesan School for Girls.