Emergency Concrete Cutting: What Happens When You Call Out of Hours

The phone goes at eleven at night. Something has failed, and concrete is in the way of putting it right. At that point you are not interested in what plant we own. You want to know what happens next, in what order, and what is realistically achievable before morning. This article sets that out plainly, including the parts of the process that do not move just because the job is urgent.

Shepherd and Sons are a family run cutting and drilling contractor of more than forty years, working from a yard at Little Westerhill Farm in Linton, near Maidstone. We have completed over 300 cutting and drilling projects across the UK in the past six years. A large share of those ran at night, inside a possession that could not be extended. From that work we've found that out of hours jobs rarely go wrong at the blade. They go wrong in the first ten minutes on the phone, before anyone has left the yard. So that is where this starts.

Urgent and emergency are not the same thing, and treating one as the other costs money. An out of hours callout means night rates, a crew called off rest, and a mobilisation that compresses planning into an evening. It is worth paying for when the alternative is worse. Four situations usually justify it.

• A structural opening needed to reach a failure. A burst main behind a wall, a failed bearing, a damaged element inside a slab. Nothing can be inspected, let alone repaired, until an opening exists.
• A burst or a flood with nowhere for the water to go. A drainage penetration through a slab or a retaining wall takes the head off the problem while the permanent repair is worked out.
• A slab failure on a live carriageway, apron or hardstanding. A broken bay on a running surface is a hazard tonight, not next month. The lane or the stand stays shut until the failed concrete is cut out and the edge made safe.
• Plant, a lift or a vehicle trapped behind concrete. A seized hoist, a machine that has to come out of a basement, a car stuck in a shaft. The concrete is the only thing between an engineer and the fault.

The common thread is that concrete is the obstacle rather than the objective. Nobody rings at midnight because they want a hole. They ring because something else cannot start until the hole is there. That matters more than it sounds. It decides what counts as finished for the night, and it is usually not what the caller first asks for.

Every answer changes what goes on the lorry. Loading the wrong machine is the most expensive mistake available at that hour. A second trip back to Linton is the rest of the night gone. So the call is not a formality, and it helps enormously if the person on the line can actually see the problem.

Where is it, exactly. A postcode is only the start. What matters after that is whether the working position is airside, behind a barrier, inside an occupied building or on a running lane. That decides the escort, the permit and the traffic management. Those routinely take longer to arrange than the cut itself.

What is the concrete, and how thick. Reinforced or mass, slab or wall, floor or deck. If nobody knows the thickness, say so rather than guessing. A guess is more useful than a silence, and so is anything physical you can measure. The depth of an adjacent drainage chamber, the step down at a doorway, the edge of the slab where it meets a gully. At two in the morning a rough figure someone has actually looked at beats a drawing nobody can find.

Thickness then decides the method, because reach follows blade diameter rather than engine power. Our floor saws give a confirmed 625mm in one pass. A wall saw reaches a little under half its blade diameter, and the largest in common use manages around 730mm from one face. Where both faces can be reached, cutting from each side roughly doubles that. Past that, or where only one face is reachable, or where there is no room to swing a blade at all, the answer is wire sawing. There is more detail on how deep concrete can be cut if you want it.

What is on the other side of it. People find this an odd question at midnight. It is the one that stops an emergency becoming an incident. An occupied room, a live substation, a tank, a fuel main, a ceiling void full of services. It changes whether we saw, core or stitch drill, and it changes who needs to be standing there while we do.

Is the area live. Live traffic, live aircraft movements, a running warehouse, a production line that has not stopped. A live area is not a reason to refuse the work. It is the reason the plan takes the shape it does, and why the isolation and the handback time get agreed before anyone starts a machine.

Who can grant access, and are they reachable now. This is the single most common cause of a wasted night. A crew standing at a locked gate at one in the morning is not cutting anything. We need a name and a mobile number for the person who can open the site and sign the permit. Not the person who can find that person tomorrow.

Is there power and water. Diamond cutting is a wet process by design. Water cools the segments, flushes the kerf and suppresses respirable silica dust. If there is no supply we bring our own, and we need to know that before we load rather than after. Power works the same way. Where there is mains we run at 110V through an RCD protected transformer, with the connections kept up out of any standing water. Where there is no mains, engine driven plant covers it, but not in an enclosed basement or plant room. Exhaust in a confined space is a carbon monoxide risk, so that situation needs either ducted extraction or hydraulic plant with the power pack outside.

There is one more question, and it is not about the concrete at all. What has to be true by morning. Sometimes the answer is a repaired main. Sometimes it is simply a road open at six, with the repair still to come. Those are different jobs and they get loaded differently.

Cutting blind into a slab is how an emergency turns into an incident. That risk does not shrink because it is dark and somebody senior is under pressure. Reinforcement, post-tensioning, conduit, drainage and live cable all sit inside concrete, and none of it announces itself from the surface.

So the cut line gets scanned before it gets cut. A cover meter and a ground penetrating radar pass across an opening the size of a doorway takes minutes. Marking up takes a few more. Set against a severed cable or a cut tendon, that is not a delay worth arguing about at any hour.

In our experience the pressure to skip the scan comes from a good place. Someone wants their site back and every minute feels like it belongs to them. The practical answer is to run the scan while the plant is being set up, rather than treating it as a stage of its own. Post-tensioned slabs are the one case where nobody should be talked round. A cut tendon releases stored energy, and the consequences reach a long way past the hole.

Where the scan says the line as drawn is unworkable, we move it or change method. Stitch drilling a row of overlapping cores forms a cut line with no percussive energy going into the structure. That is how we have worked alongside live services before, including a high-pressure aviation fuel main. It is slower than a saw. It is a great deal faster than an investigation.

Here is the honest version, because the alternative is useless to you at midnight. Our crews and our plant start from Linton, near Maidstone. A site in Kent is reached quickly. Maidstone, Ashford, Medway, Sittingbourne, Canterbury and the M20 corridor are all close to home, and the roads are empty at that hour.

A site the far side of London is not reached as quickly. London, Sussex and Essex all sit inside our normal working area. The travel is still real, and the M25 has its own opinion about the hour. A lorry loaded with a wall saw and a power pack does not make up time.

We do not publish a response time in minutes, and we would be wary of anyone who does. What we will do on the phone is tell you honestly whether we can help tonight. Occasionally the right answer is that your interests are better served by someone closer to you. That conversation takes two minutes and it has saved people a wasted evening more than once.

Most out of hours work splits into two parts. The first is making the situation safe and reachable. The second is putting the surface back permanently. Those rarely belong in the same visit, and it is better to say so at the start than to discover it at four in the morning.

On a straightforward opening, a single night visit can usually cover the following.

• Scanning and marking the cut line, and agreeing it with whoever owns the structure.
• Cutting or coring the opening, and lifting the sections out.
• Making the edges safe, so nothing is left sharp, loose or undermined.
• Boarding, plating or barriering off the opening for the rest of the night.
• Clearing the slurry and leaving the area clean enough to hand back.

What generally needs a second visit is the finish. Permanent joint sealing needs a slot that is clean, sound and dry, and a wet opening at three in the morning is none of those. Reinstatement concrete needs to cure before anything runs over it. Line marking needs a surface temperature a February night will not give you. Forcing those into the first visit produces work that fails, and you pay for it twice.

This is the part that gets forgotten once the immediate crisis has passed. A hole cut into a slab at two in the morning is a new hazard from the moment it exists. It needs managing with the same seriousness as the failure that caused it.

Water is the first issue. An open cut in a concrete pavement lets water straight down to the sub-base. A saturated sub-base under traffic pumps and loses support, and the slab starts moving at the joint. The sawn edge is a separate problem, because an unsupported arris takes the wheel loads directly and breaks down. Exposed reinforcement begins corroding straight away. On a floor or a deck, an unguarded opening is a fall risk for whoever arrives before the morning briefing. On a carriageway or an apron, loose material is foreign object debris, and that is somebody's incident report.

So the temporary condition gets designed rather than improvised. That means a cover rated for whatever will cross it, edge protection that is still standing at eight, and a written agreement about who owns the opening until we return. On an airside job that is a formal handback with a sweep and an inspection behind it. A warehouse floor deserves the same treatment, even though nobody insists on it.

None of this is difficult, and none of it costs anything. It is the difference between a crew cutting at midnight and a crew waiting at midnight.

• A named person on site with keys, plus their mobile number.
• Whatever drawings exist, even old ones. A drawing we know to be unreliable still tells us something.
• The permit route. Who signs it, and whether they are contactable tonight.
• Confirmed isolations for any service near the cut line, in writing where the site requires it.
• Somewhere for the lorry, close enough to run leads and hoses without crossing a live route.
• A water supply and a drain, or a decision about where the slurry goes. Cutting slurry is strongly alkaline and must not reach a gully or a watercourse.
• A clear statement of what has to be true by morning, and the name of the person who decides when it is.

Two of those are worth pushing on. The access contact, because a locked gate stops everything. The slurry route, because on a port or an airfield it is a permit condition rather than good housekeeping, and it will stop the work if nobody has thought about it.

Call 07768 662153, and describe what has failed rather than what you think needs cutting. We will work the method out from there. We are SafeContractor and CHAS accredited and members of the Extruded Sealant Association. We have been sole contractor for the British Airport Authority since 2008, working across all seven former BAA airports. That is a discipline built entirely on possessions that hand back at a stated time, whatever has gone wrong inside them.

For the service itself, see emergency concrete cutting. If the job can wait until morning, and a fair number can, get in touch with our team and we will programme it properly instead. That is nearly always the cheaper night.