How We Wire Sawed a 4800Γ2750mm Reinforced Concrete Opening Beneath Occupied Flats
By Diamond Drilling UK β’ Specialist Concrete Cutting & Breaking β’ diamonddrillinguk.com
Some jobs are more than just concrete cutting. Theyβre exercises in precision planning.
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The Project
We were commissioned to form a large structural opening through a heavily reinforced concrete slab in a mixed-use building. The ground-floor commercial unit sat directly beneath a block of occupied residential flats, meaning every decision made on site had a direct impact on the people living above.
The opening measured 4,800mm wide by 2,750mm tall through a 500mm-thick reinforced concrete slab. To put that in context β 500mm of R/C is serious mass. The combined weight of the concrete being removed ran to several tonnes, the structural implications required meticulous planning, and the presence of tenants overhead meant working hours were tightly controlled.
The Challenges
Before a single wire was threaded through the slab, we had four significant problems to solve.
β’ Load on the crash deck. Dropping tonnes of broken concrete onto a crash deck in one go risked overloading it. We had to sequence our cuts carefully to control how much weight landed at any one time.
β’ Water control. Wire sawing requires a continuous water feed for cooling and dust suppression. In a live building, uncontrolled water is simply not an option. Containment had to be engineered into the plan from the outset.
β’ Restricted working hours. The residential tenants above placed firm limits on when we could operate. Noisy, vibratory work had to be scheduled within agreed windows β extending the programme, but protecting the occupants.
β’ 500mm of heavily reinforced concrete. The slab density and reinforcement content put this well beyond standard floor sawing or coring. Only a high-powered wire saw configured for this depth could deliver clean, controlled cuts.
The Method: 1 Metre at a Time
The solution was a carefully staged programme using two pieces of specialist equipment working in tandem: a Pentruder wire saw and a Brokk 90 remote-controlled demolition robot.
Rather than attempting to cut the entire opening in one operation β which would have produced an unmanageable volume of concrete dropping at once β we cut 1 metre back at a time, breaking each section out before moving to the next.
Step 1 β Site Setup & Crash Deck Installation
A robust crash deck was installed below the opening zone. Its load capacity was matched against the weight of a single 1m-wide panel of 500mm R/C, ensuring no single drop would exceed safe limits.
Step 2 β Water Control System Established
Our team designed and fitted a water collection and containment system to capture all cooling water from the Pentruder saw. Channels, dams, and collection points were established before cutting began to prevent water from tracking into the building fabric.
Step 3 β Pentruder Wire Saw: First 1m Section Cut
The Pentruder wire saw was set up and threaded through pre-drilled pilot holes in the slab. The diamond-impregnated wire ran through the full 500mm thickness, making clean, precise cuts on three sides of the first 1m section.
Step 4 β Brokk 90: Controlled Break-Out
The remote-controlled Brokk 90 robotic breaker was deployed to break the cut section and direct it down onto the crash deck below β with our operator positioned safely away from the drop zone at all times.
Step 5 β Debris Cleared, Sequence Repeated
Each broken section was cleared from the crash deck before the next cut commenced. This maintained safe deck loading throughout and gave the team clean working conditions for every subsequent sequence.
Step 6 β Full Opening Achieved
The process was repeated across the full 4,800mm Γ 2,750mm opening until the entire void was created cleanly, structurally sound, and within specification β without incident.
Why Wire Sawing Was the Right Choice
At 500mm thick, this slab was beyond the practical reach of floor saws, wall saws, or standard coring equipment. Wire sawing is uniquely suited to large, thick, or irregularly shaped cuts because the diamond wire can navigate around rebar and follow a precise line regardless of depth or section geometry.
The Pentruder wire saw system is among the most capable in the industry β engineered for exactly this type of high-specification structural cutting. Its precise tension control allows operators to cut cleanly through the most heavily reinforced concrete without the cracking or vibration that conventional methods can introduce.
The Role of the Brokk 90
Once each section was wire sawed on its perimeter, the concrete panel still needed to be broken away and directed onto the crash deck. The Brokk 90 was the right tool for this.
Working remotely meant our operators were never directly beneath a suspended or partially cut panel β a non-negotiable safety requirement on a job like this. The Brokkβs compact footprint also meant it could be positioned precisely without interfering with the wire saw setup or the surrounding structure. The combination of wire saw and Brokk is one of the most effective pairings available for controlled structural demolition.
Working Around the Residents
One of the most operationally complex elements of this project had nothing to do with the concrete itself β it was the people living above.
Our programme was built around agreed working windows that avoided early mornings, evenings, and weekends. The heaviest cutting and breaking was scheduled during the least sensitive periods of the day, while setup, water management, and debris clearance made productive use of restricted hours without generating significant noise or vibration.
This kind of programme management is standard practice for Diamond Drilling UK in occupied or sensitive environments. We understand that for residents, a drilling contractor on site is β at best β an inconvenience. Our job is to make that impact as small as possible, while delivering a technically flawless result.
Why You Should Never Attempt This Without Specialists
A 500mm reinforced concrete slab in a live building is not a job for a general contractor without specialist equipment, structural knowledge, and a properly engineered method.
β’ Cutting through load-bearing R/C without the correct sequencing, temporary propping, and structural sign-off can cause catastrophic, irreversible damage.
β’ Uncontrolled water will track into structural elements and destroy finishes.
β’ Falling concrete sections, if not properly managed, will overload temporary works β with potentially fatal consequences.
Specialist contractors exist precisely because this work carries serious risks when handled by the wrong team..
What a Professional Brings to a Job Like This
β’ The right equipment. Pentruder wire saws and Brokk robotic breakers are significant capital investments. Without them, this opening simply cannot be made safely at 500mm thickness.
β’ Structural understanding. Professional concrete cutting contractors work alongside structural engineers and understand the implications of every cut before a single tool is switched on.
β’ Proper paperwork. A comprehensive method statement and risk assessment are mandatory on a project of this complexity. We produce these as a matter of course and work within them rigorously on every job.
β’ Water management expertise. Controlling water on a live site requires engineered containment, not improvisation. Getting it wrong means damage, delays, and disputes.
β’ Proven experience. Diamond Drilling UK has built its reputation on projects that demand exactly this level of technical precision β and we have the track record to back it up.
Talk to Diamond Drilling UK About Your Project
Whether you're a structural engineer, facilities manager, civil contractor, or local authority, if you have a problem that requires precision drilling β we want to hear about it.
We work on projects of all scales across the UK, from routine core sampling to complex, sensitive structural interventions.
π Call us: 020 3286 3428 / 01424 720259
βοΈ Email us: info@diamonddrillinguk.com
π Visit our website: diamonddrillinguk.com
π Serving clients across the UK,
We're available to discuss your requirements, provide technical guidance, and offer project-specific advice β no obligation, no jargon.
Here at Diamond Drilling UK Ltd, we offer a range of services using core drilling and diamond drilling technologies, offering our customers the most precise work possible. Today weβre going to pay particular attention to our range of diamond sawing services, which include wall sawing, floor sawing, and wire sawing. Read on to find out more.
Diamond Wall Sawing
Wall sawing is typically used to cut accurate openings in walls, for the purpose of creating space for doors, vents, and windows. It is also known as track sawing as it uses a track-mounted system, which bolts to the wall in order to create the necessary openings. This type of sawing may also be used to create separation joints before a demolition project for easy access. Wall saws make use of a circular diamond blade for straight, smooth openings in walls. It is possible to use a 3-phase hydraulic wall saw, or a 3-phase high frequency wall saw.
Diamond Floor Sawing
Another method for creating openings in reinforced concrete is diamond floor sawing. It works in a similar way to wall sawing, but is best suited to applications on a horizontal level, such as forming openings for service ducts, ventilation ducts, lift shafts and escalators. Again, it is also used as a technique prior to any necessary demolition. Additionally, other applications it may be used for could be cutting expansion and crack inducing joints. You can also form trenches for utility contractors, and create clean-cut edges within concrete slabs. In addition to concrete, itβs also possible to use floor sawing for asphalt services like motorways, bridges and pavements.
Diamond Wire Sawing
As the name suggests, diamond wire sawing makes use of a metal wire or cable. The diamond beaded wire wraps around the structure (either concrete or masonry) and then this wire is fed through a series of pulleys before being tensioned. Lastly, through a process of rotation, the wire is pulled through the concrete in order to cut through it. The structure can be nearly any size or shape, and it is the perfect method for cutting through large structures made from reinforced concrete, whether bridge sections, jetties, columns, or beams. Due to the flexible nature of diamond wire sawing, it can be ideal for use on both extremely tick or awkward concrete shapes.
Contact Us
If you would like more information about our diamond sawing services, please donβt hesitate to get in touch through our web contact form, or via email at info@diamonddrillinguk.com. Based in East Sussex, we also have offices in London, so simply visit our contact page to find the relevant number to speak to a member of the team directly. A member of our team will be happy to help you with any questions you may have about diamond sawing or any of our other services.
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