Wall Sawing and Rooftop Wall Removal, Bay Street, Double Bay

The job

Venari Projects is building a new multi level building on Bay Street in Double Bay. On the roof, a run of cast in place concrete walls and planter boxes had to change: some walls had to come out completely and others had to be cut down to a new, lower level. That work came to Perfect Concrete Care.

Our crew was on the roof from March to April 2026. The walls were scanned, braced, cut into blocks and lifted out, the lowered walls were cut and broken down to the new level, and the slab was broken back and patched where the walls had been.

What we did

• Concrete scanning of the walls and slab before any bracing or cutting, so the props and cuts missed the reinforcement and services that mattered
• Marking every cut line and section on the walls, and putting protection in place around the work area
• Bracing each wall with steel props fixed to the wall and the slab, so no section could move while it was being cut
• Wall sawing and hand sawing the walls into blocks small enough to handle and take off the roof
• Cutting walls down to the new level marked on them, saw cutting the top in a grid and breaking it down to leave the bars exposed
• Breaking back the wall bases into the slab, cutting off bar stubs, and breaking back concrete on the underside of a beam inside the building
• Grinding the cut lines and patching the slab with repair mortar so the roof was ready for the next trade

What made it hard

This was cutting on a finished structure, on the roof, with the building full of other trades below. A wall section that moves while it is being cut can pinch a blade, fall, or damage the slab, so nothing was cut until it was braced. Many of the walls were curved, which means the cut lines and the props had to follow the shape.

Every block that came off the walls had to be handled on the roof and taken away, so the blocks had to be sized for that before the first cut. The walls being lowered had to finish at an exact level, with the existing bars left in place for the work that followed. And the slurry from wet cutting had to be kept off the roof drains and out of the areas below.

How it was done

The first days were set up: scanning all areas where props would be fixed, marking every area to be cut, and installing protection. Then the props went in and the cutting started, wall by wall. Walls coming out completely were sawn into blocks, which were stacked on the roof and taken away.

Walls being lowered were saw cut across the top in a grid of slots down to the new level, then broken out by hand so the vertical bars were exposed and not damaged. Once the walls were gone, the bases were broken back into the slab, the lines were ground, and the slab was patched with repair mortar. Our part of the job was finished and signed off in April 2026.

Lessons learned on this job

Every job teaches the crew something. These are the ones we took from the Double Bay roof, and we use them on every wall sawing job.

What worked

• Scan before you brace. Scanning where the props would be fixed meant the anchors went in clear of the reinforcement and services
• Brace first, cut second. Propping every wall before cutting kept each section still, so the blades did not bind and nothing dropped
• Size the blocks for handling. Deciding the block size before cutting made moving them on the roof simple
• Slot the top, then break. Cutting a grid of slots across the top of a wall made it quick to break down to the level without damaging the bars

What was difficult

• Curved walls. Cut lines and props have to follow the curve, which takes longer to set out than a straight wall
• Working above other trades. Slurry, dust and noise had to be managed so the floors below could keep working
• Services under the roof. Breaking back concrete inside the building had to be done carefully around live services
• Exact levels. A wall cut down to a marked level leaves no room for error, so every cut was checked against the level on the wall

If you have something similar

Builders often need concrete walls cut out or cut down on a finished structure, without damaging what stays. Have a look at our specialist wall sawing and concrete cutting Sydney pages, or get in touch.