What is the difference between a construction joint and a saw-cut joint?

A construction joint is where one pour physically ends and the next begins. A saw-cut joint is cut into a single continuous pour afterwards, at a planned spacing, to control where shrinkage cracking occurs.

Why does an armoured joint exist if a normal joint works elsewhere?

Armouring protects the joint edge with steel where heavy, constant wheel traffic would otherwise chip it — it is a response to load and frequency, not a universal upgrade every joint needs.

Does a chipped joint mean my floor is failing?

Not necessarily. Spalling is extremely common and is usually a maintenance and repair matter rather than a sign the slab itself has failed — but it will not fix itself, and it does get worse with continued traffic.

Can spalling be prevented once a floor is poured?

Properly specified and maintained joint fillers, and armouring on heavy-traffic joints, both reduce the risk. Once curling and voiding have already started at a joint, the practical question shifts from prevention to repair.

Slab joints and spalling: the most common defect on an industrial floor

Nearly every operational warehouse floor has chipped joint edges somewhere, and most people who walk past them daily could not name the defect or explain why it happens. It wrecks forklift tyres, shakes loads, and gets worse the longer it is ignored.

Last updated 2026-08-24

Three kinds of joint

A construction joint marks where one concrete pour genuinely ends and the next begins — a real discontinuity in the slab. A saw-cut (or contraction) joint is different: it is cut into a continuous pour after placement, at a planned spacing, to make shrinkage cracking happen at a chosen line instead of somewhere random. Both are normal and necessary on any large industrial pour; a slab this size cannot be poured or left to shrink without them.

An armoured joint is typically a construction joint carrying heavy wheel traffic, with its edges physically protected by steel angle or channel cast into the slab on both sides, with dowels through the armour transferring load across the gap while still letting it open and close with temperature and moisture movement. Armouring shows up specifically where forklift traffic crosses a joint constantly, which is most of a warehouse floor.

Why the edges chip: the mechanism

Spalling and arrising follow a consistent sequence. The top and bottom of the slab dry and cool at different rates, which curls the slab edges either side of a joint upward — covered in full in why concrete floors crack and curl. That curl leaves a void beneath the slab edge at the joint. An unsupported or poorly filled edge, struck by a hard wheel, has nothing underneath to resist the impact, so the concrete edge acts as an unsupported lever and the sharp corner — the arris — chips. Once one chip has opened the edge up, the next wheel pass finds an even more vulnerable target, so the defect widens with continued traffic rather than staying still.

Unfilled joints, a flexible sealant used where a rigid or semi-rigid filler was actually needed to support the edge, poor filler installation, and a saw cut left ragged by a worn blade all make the problem worse. None of these are unusual conditions on an older floor.

What it costs before anyone calls it structural

Spalled joints are a genuinely dual-owned problem. They shred forklift tyres over time, which is a facilities cost most operators track. What gets missed is the second cost: every wheel that crosses a spalled joint transmits a jolt through the truck and into whatever it is carrying, and a jolted load is a load-placement and stability event on the racking it is about to be set into or has just come from. Forklift tyre wear and floor condition are frequently the same story told from two different departments.

Cosmetic today, worse tomorrow

A single small chip is a maintenance item. Left alone, the mechanism above does not reset itself — the exposed edge stays exposed, and every pass widens it a little further. That is the argument for treating joint condition as something to note during routine floor and facility checks rather than waiting for it to become visually obvious, in the same spirit that a competent person inspecting racking is looking at the whole system the load sits in, floor included.

What repair actually involves once a joint has spalled, and how that differs from letting a floor go until it needs replacing, is covered in floor repair.

Common questions

What is the difference between a construction joint and a saw-cut joint?: A construction joint is where one pour physically ends and the next begins. A saw-cut joint is cut into a single continuous pour afterwards, at a planned spacing, to control where shrinkage cracking occurs.
Why does an armoured joint exist if a normal joint works elsewhere?: Armouring protects the joint edge with steel where heavy, constant wheel traffic would otherwise chip it — it is a response to load and frequency, not a universal upgrade every joint needs.
Does a chipped joint mean my floor is failing?: Not necessarily. Spalling is extremely common and is usually a maintenance and repair matter rather than a sign the slab itself has failed — but it will not fix itself, and it does get worse with continued traffic.
Can spalling be prevented once a floor is poured?: Properly specified and maintained joint fillers, and armouring on heavy-traffic joints, both reduce the risk. Once curling and voiding have already started at a joint, the practical question shifts from prevention to repair.

Part of our guide to the floor and what is bolted to it.