Become a partnerLaminate on an uneven floor: thickness, class and locking systems
“My floor is a little uneven. Will thicker laminate solve it?” This is a common question during renovation. Thick laminate and a strong locking system are not a levelling layer. Without proper support, boards can flex, make noise and separate at the joints. A good choice starts with measurements.
Start by measuring “uneven”
Place a long straightedge in several positions and directions. Measure the gaps beneath it and note high and low spots. An overall slope is different from a local hollow: laminate needs a flat surface and stable support.
Use the tolerance stated in your model's installation instructions. For example, Quick-Step's guidance for installation over an existing timber floor requires deviations greater than 4 mm over 2 metres and 1 mm over 20 cm to be levelled. This is not a universal allowance for all brands and models; your product may require a stricter tolerance.
A simple example: if the instructions permit 4 mm over 2 metres and you measure 6 mm, buying 12 mm laminate does not make that base suitable. Identify the cause of the hollow and the appropriate preparation method first.
8, 10 or 12 mm?
| Thickness | What to consider |
|---|---|
| 8 mm | May suit renovations with limited door and transition clearance. Suitability still depends on the model and the prepared subfloor. |
| 10 mm | Calculate the finished height including underlay. Do not treat extra thickness as an allowance for hollows. |
| 12 mm | Creates a higher floor build-up and may affect doors and transitions. It does not permit installation on an unsuitable uneven base. |
Thickness alone is not a measure of quality. Assess surface performance, intended use, underlay and installation conditions together, and include preparation in the budget.
Which use class is suitable?
Use classes such as 32 and 33 describe the intended intensity of use. The class does not measure tolerance of an uneven subfloor. Class 32 covers general commercial use and class 33 heavy commercial use. Check the individual product's suitability for domestic use and the chosen room as well.
A bedroom and an entrance hallway face different demands. Choose according to traffic, moisture risks and the manufacturer's conditions. Higher-class flooring still needs a properly prepared base.
Which locking system is better?
A click joint connects boards; it does not fill voids underneath. The name Uniclic, or any other system, does not itself promise better performance on an uneven floor. Even support, compatible underlay and correct assembly are essential for the joints to last.
Request the fitting instructions before purchasing. Check the assembly angle, whether disassembly and refitting are allowed, and which tools are needed. If a joint is damaged, separate and inspect the board instead of forcing it into place.
Will a soft, thick underlay solve the problem?
Suitable underlay may accommodate very small local irregularities, but it does not level broad hollows. An overly compressible underlay can increase movement and stress the joints. Check manufacturer approval and compressive performance, not just thickness.
Do not stack two underlays. Add an extra layer under laminate with an attached backing only if the manufacturer expressly permits it. Do not retain old carpet as laminate underlay. Concrete and timber have different moisture-control requirements and should not automatically receive the same solution.
A short checklist before buying
- Check the substrate type, flatness and moisture condition; repair moving areas.
- Compare your measurements with the product instructions and plan the required levelling.
- Calculate the total height of laminate, underlay and preparation layers.
- Choose suitable performance for the room and maintain expansion gaps and transitions as instructed.
In our laminate catalogue, compare Kaindl, Classen, Clix Floor and Quick-Step models alongside your measurements. If the base is too uneven, choosing the right preparation method comes before choosing a thicker board.