A large continuous floor that cracks or lifts over time almost always has the same explanation: it lacked an expansion joint somewhere, and the material simply had nowhere to absorb the thermal movement.
How often to include a movement joint
As a guide, on large surfaces an expansion profile every 40–50 m² or so is advisable, or whenever the floor crosses a structural joint of the building itself. It is a movement joint in continuous floors, which stops the floor cracking or lifting through thermal expansion.
The grout joint also has a mechanical function
On floors, the joint between tiles is not only aesthetic: it absorbs part of the expansion between pieces. Don't make it narrower than the manufacturer recommends just for looks — consumption is calculated the same way as on a wall (area × joint width × 0.15).
Worked example: for 25 m² with a 3 mm joint: 25 × 3 × 0.15 = 11.25 kg, rounded up to 3 bags of 5 kg. This is the same calculation the PresupuestoYa calculator applies automatically for the Floor Layer trade.
Levelling system: almost mandatory in large format
The levelling system of clips and wedges keeps two floor tiles at the same level while the adhesive cures, avoiding lippage underfoot. It is almost essential in large format (75×75 cm and up): without it, a height difference of just 1–2 mm between neighbouring tiles is noticeable and catches when a piece of furniture on wheels goes over it.
Frequently asked questions
What happens if I don't put expansion joints in a large floor? The floor can crack or lift through thermal movement, since there is no point where that expansion can be absorbed.
From what tile size is a levelling system mandatory? It isn't mandatory by regulation, but it is almost essential from 75×75 cm, where any lippage between tiles is very noticeable underfoot or when moving furniture on wheels.
How much grout do I need for 40 m² with a 5 mm joint? 40 × 5 × 0.15 = 30 kg, rounded up to 6 bags of 5 kg.
Conclusion
Planning expansion joints every 40–50 m² and using a levelling system in large format are two decisions made before you start laying, not after. They are the difference between a continuous floor that lasts for years without problems and one that starts showing faults within a few months.
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