Antrim House roof restoration

Our team spent seven months restoring and strengthening the roof at Antrim House, a Historic Place Category 1 listed building completed in 1905 and the national office of Heritage NZ. The tenants moved out for the duration, leaving our team free to encapsulate the entire building in an elaborate shrink wrapped scaffold and get to work.

We installed new roofing iron and completed structural works to the ceiling diaphragm, building plywood diaphragm and jack frame supports, reinstating collar-type props that were destroyed in a 1940s fire, replacing damaged sarking, and adding roof access hatches. The roofing works also included fabrication of a new lead dome at the top of the tower to replace the 1940s one from a previous rebuild.

We also reduced the unreinforced masonry chimney stacks to ceiling height and drilled 12 14-metre-long cores to hold stainless steel tensioning rods to seismically brace them. We opted for dry core drilling rather than wet drilling, avoiding the risk of water and slurry entering the building and damaging the heritage fabric.

We used a bespoke mix of modern and traditional techniques on the project, engaging specialist contractors from around the country. This involved working closely with Heritage NZ to ensure that the workmanship was of the highest quality while staying within budget, providing multiple scope package options. They were delighted with their new roof, inviting everyone involved to sign a commemorative plaque and leave our mark on Antrim House’s 119-year history.