Henley Lift Shaft Case Study: Priced as a Tunnel, Built as a Trench

Some of the hardest excavation in Sydney happens on small sites. This one was a house in Henley, on the Parramatta River side of Gladesville, where a couple who wanted to stay in their home as they got older needed a lift. The house sits on a sandstone shelf with the garage cut into the rock underneath, so a lift meant a shaft cut down through solid Hawkesbury sandstone to connect the yard above with the garage below. There was no room for a big machine, no room for a crane and no room for error, because the rock we were cutting was also holding up the house.

This case study covers how the job came to us two years before a machine turned up, how Perfect Contracting cut the shaft from inside the garage, how the spoil got out through a suburban street, and the biggest lesson of the job: we priced it as a tunnel and built it as a trench.

The short version. A two person crew, a 3.5 tonne and a 2.5 tonne excavator with hydraulic breakers, a tracked dumper and a hook lift truck did the rock work in two stages between July and October 2026, working under the owners' builder. Around thirty skip bins of sandstone left the site. No incidents were recorded, the daily diaries show no delays and no variations, and the project manager's inspections found the work on programme with no defects or rework.

How the job started: a methodology before a DA

The owners came to us in 2024, well before they had a builder or an approval. They did not want to sell up and move into something on one level. They wanted to stay in their own house, and the only way to do that was a lift between the garage and the house. What they needed first was someone to tell them whether a shaft through the rock was even possible, and roughly how it would be done.

Perfect Contracting priced it as a tunnel excavation and gave them a written methodology: how the rock would be cut, how the house would be protected, how the spoil would get out and what it would take. That gave the owners enough confidence to go to council for a development approval and then find a builder for the rest of the renovation. Two years later, with the DA in hand and the builder running the site, we were back to do the rock work we had described. Early advice on a hard problem is often what wins the job later, and this is a good example.

The site and the scope

The house sits on a steep block that drops towards the river. Like a lot of homes around Henley, Hunters Hill and Gladesville, it was built on and into a sandstone shelf. A concrete garage was cut into the base of the shelf years ago, and the living areas sit on the rock above. The lift and stairs had to go between those two levels, which meant cutting a shaft through the rock between the garage and the yard.

Our scope, working as a subcontractor under the builder, was the rock work: open up the back wall of the garage, cut through the sandstone to the line of the new shaft, open it up to the yard above and get every tonne of spoil off site without damaging the house, the neighbours or the street. Service trenches were cut through the rock as part of the same scope.

The constraints were the usual ones for tunnelling and low vibration excavation under existing buildings, only tighter. The only way in was through the garage door. The ceiling height was a standard garage ceiling. The sandstone wall we were cutting carried the building above it, so vibration had to be managed from the first hit. And the street outside was a quiet residential road with cars parked on both sides and people walking past.

Why small machines and breakers, not blasting or big plant

There are three ways to get through sandstone on a job like this: blast it, cut it with saws and wire, or break it with hydraulic breakers. Blasting was out from the start. You do not blast under an occupied house in a suburban street. Diamond cutting is good for a clean finished face and we used a demolition saw to score the lines and relieve the edges, but sawing the full volume out of a shaft would have been slow and expensive.

Hydraulic breakers on mini excavators were the right tool for the bulk of it. Hawkesbury sandstone is a soft to medium rock. A hydraulic hammer on a 3.5 tonne machine breaks it steadily without the shock of blasting, and the machine is small enough to drive through a garage door and turn around inside. We ran a 3.5 tonne excavator as the main breaking machine, with a 2.5 tonne machine alongside it and a 0.8 to 1 tonne mini for the tight corners where the bigger machines could not reach. When the breaking was done the small machines swapped to buckets and rippers for the service trenches.

The sandstone wall being cut was also the wall carrying the house, so vibration was the risk the project manager flagged on his first site inspection. The controls were simple and old fashioned. Keep the hammer sharp. Break towards a free face so the rock has somewhere to go rather than transmitting energy into the wall. Take smaller bites as the cut gets closer to the finished line. Score the finished line with the saw first so the break follows the cut rather than wandering into the rock that stays.

Priced as a tunnel, built as a trench

The methodology we gave the owners in 2024 was a tunnel: a closed heading driven through the rock from the garage to the shaft line. That is how it was quoted and that is what everyone expected. Once we were on site with the garage opened up and the rock in front of us, the better answer was an open trench. Instead of mining a blind heading and dealing with everything that comes with it, the crew opened the shaft line from above, cut the rock as a trench between two clean sandstone walls, and propped the garage structure over it.

An open cut is easier on every count. The operator can see the rock and the finished line. Spoil comes straight out of the top of the cut instead of being dragged back along a heading. There is no confined space to ventilate and no overhead rock to support while you work under it. It is faster, it is safer and it costs the owner less. The photos of the opening from ground level show how small the disturbance to the yard was: the rock around the shaft was left intact and the edges were cut, not blown out, and the opening was fenced and covered at the end of each day.

The lesson is not that the tunnel methodology was wrong. It was the right answer for a couple deciding whether to go ahead with a renovation, because it showed them the job could be done whatever the ground turned out to be. The lesson is to keep looking for the simpler way once the rock is in front of you, and to pass the saving on.

Getting the spoil out

Breaking the rock was the easy part to plan. Moving it was the problem the crew raised with the project manager on his first visit: material load out logistics. Every tonne of sandstone broken at the back of the garage had to travel to the garage door, out across the driveway and into a bin in the street, and the street had room for one bin at a time.

The answer was a tracked dumper. The excavator loaded broken rock into the dumper at the face, the dumper tracked it out through the garage and tipped it into a 10 cubic metre skip at the kerb, and our own hook lift truck swapped the full bin for an empty one. In the first week the diaries record one full 10 cubic metre bin of sandstone a day. Over the whole job the hook lift trucks made around thirty bin changes. Running our own trucks mattered here, because a bin change on a narrow street has to happen when the street is clear, not when a hire company's schedule says so. A skid steer loader joined the job for a fortnight in August when the volume of loose material in the garage was at its highest.

With a machine working at a rock face inside a garage, air quality matters. A ventilation fan with ducting ran into the work face so that dust and exhaust were pulled out rather than left to sit in the garage, water was used on the breaker and the stockpile for silica suppression, and respiratory protection was part of the daily pre start.

Keeping the neighbours onside

A house in a quiet street with trucks changing bins is a job that gets complaints if it is run badly. The garage opening was screened with shade cloth on temporary fencing, with our signage on it so anyone walking past knew who was working and what the hazards were. Hours were a straight 7am to 3.30pm. Bin changes were coned off and done quickly. Pedestrian traffic past the driveway was one of the two environmental risks the project manager noted, and the screening and the coned bin changes were how it was managed. No complaints are recorded in the diaries.

Two stages, one crew, under the builder

The job ran in two stages under the owners' builder. The first, from late July to mid August 2026, was the breaking out of the shaft and the bulk of the spoil removal. The second, from early September into October, was the remaining rock work and the service trenching, sequenced around the builder's other trades. On both stages the crew was two people, a supervisor and an operator, with the drivers for the bins and the float coming in as needed. Running a small crew on a small site is a deliberate choice: it keeps the garage workable, keeps the cost down for the owner and means the same two people know the rock, the house and the neighbours from start to finish.

What it delivered

A lift and access shaft cut through sandstone at an occupied house, so a couple can stay in the home they chose instead of leaving it, with the rock that carries the building left where it belongs. Around thirty bins of sandstone off site through a narrow residential street without a recorded complaint. Service trenches cut and ready for the builder. No incidents, no delays and no variations in the daily diaries. Two project manager inspections recording the work on programme, workmanship to standard, and no defects or rework. All of it done by our own crew with our own plant and our own trucks.

Lessons learned

Every job teaches something. These are the ones from Henley that we are carrying to the next sandstone shaft.

The methodology wins the job, the site decides the method

We priced a tunnel and built a trench. The written methodology two years earlier is what gave the owners the confidence to get their approval and find a builder, so it did its job. But the moment the rock was exposed, an open cut was cheaper, faster and safer than a closed heading, and that is what we did. Quote the method that proves it can be done. Build the method the rock gives you.

Get in before the DA

By the time a builder tenders a job like this the method is already fixed in someone's head. Being the contractor who told the owners it could be done, and how, meant we were the obvious choice when the work finally started two years later.

Plan the spoil route before the first hit

The crew's one concern on the first project manager visit was load out logistics, not the rock. On a tight site the breaking is rarely the bottleneck. The distance from the face to the bin, the size of the bin the street can take and how fast you can change it decide the daily rate. Work that out in the quote and the method, not on site.

Mark the line and saw it first

Breakers wander. A sawn line on the finished profile gives the break somewhere to stop and leaves a face the builder can work to. It costs an hour of sawing and saves a day of trimming.

Keep a spare machine on the job

The smallest excavator broke down on day two and the crew lost part of a day fixing it. With a second machine on site the breaking kept going. Small machines work hard on rock, and a small site cannot wait for a float.

Ventilate from the start

A breaker working in a garage fills it with dust and exhaust fast. The fan and ducting went in on day one and stayed for the whole job. Do not wait for the air to get bad before you deal with it.

Give the owner a face

The same supervisor ran the site through both stages. The owner, the builder and the neighbours all knew who to talk to. On a residential job that is worth more than any newsletter.

Frequently asked questions

Can you cut a lift shaft through sandstone under an existing house?

Yes, and it is more common than people expect in the harbour and river suburbs where houses sit on sandstone shelves. The work is done with mini excavators and hydraulic breakers from inside the existing lower level, with the finished profile sawn first and the breaking sequenced away from the structure. Where the site allows it, an open trench beats a closed tunnel heading every time. The engineer's drawings set the shaft line and any temporary propping, and the builder usually follows straight behind with the shaft lining and lift pit.

Can Perfect Contracting help before we have a DA or a builder?

Yes, and it is the best time to talk to us. On this job the owners had a written methodology and a price from us two years before work started, which is what let them go for approval and engage a builder with confidence. Send us the survey and whatever drawings you have and we will tell you whether it can be done and how.

How is vibration controlled when breaking rock next to a house?

Mostly by method. Hydraulic breaking is low impact compared with blasting or large plant. The operator breaks towards a free face so energy goes into moving rock rather than into the wall, takes smaller bites near the finished line, keeps the tool sharp and scores the line with a saw first. On sensitive structures a vibration monitor can be set up against limits agreed with the engineer.

How do you get rock out of a site with no access for trucks?

A tracked dumper or skid steer shuttles the spoil from the face to the nearest point a bin can sit, and a hook lift truck changes bins as they fill. On a narrow street that is usually one bin at a time, changed in a coned off window when the street is clear. The rate the bins can be changed often decides the rate the rock can be broken.

How is silica dust managed when breaking sandstone indoors?

Sandstone is high in crystalline silica, so dust is treated as a health hazard and not just a nuisance. Water on the breaker and the stockpile, a ventilation fan and ducting pulling air from the face, respirators as part of the daily pre start, and breaking rock in blocks rather than grinding it to dust. Our silica regulations guide has more on the rules.

Does Perfect Contracting do tunnelling for houses as well as infrastructure?

Yes. The same crews and small plant that cut this shaft have done residential tunnelling in Mosman and cycleway tunnelling at Summer Hill. See our residential tunnelling services page for what is involved.

Talk to us about your rock

Perfect Contracting cuts shafts, trenches and tunnels through sandstone and other rock under and beside existing buildings across Sydney, NSW and South East Queensland, with our own operators, plant and trucks. Read more about tunnel excavation in Sydney and low vibration rock excavation under existing buildings, or send us the drawings and we will tell you how we would get through it.