How we measure it on site
We lay a straightedge, commonly around two metres long, across various points in the room and check the gap beneath it with a gauge. We repeat this in multiple directions because a floor can be flat one way and sloped another, particularly in older properties where settlement has occurred unevenly.
Why tolerance varies by floor finish
- Rigid click floors and large-format LVT need the tightest tolerance because they can't flex to accommodate dips without stressing the joints.
- Engineered and solid wood have moderate tolerance requirements depending on plank width and format.
- Carpet is the most forgiving, as its underlay absorbs a fair amount of minor unevenness.
What goes wrong outside tolerance
Fitting a rigid floor over an out-of-tolerance base risks joints working loose, visible rocking underfoot, and in worse cases clicking mechanisms failing at the seams. Even flexible finishes like sheet vinyl can telegraph an uneven base as visible dips once fully laid.
Bringing a floor within tolerance
- Self-levelling latex compound across the whole floor where unevenness is widespread.
- Localised patch repair at specific high or low points.
- Sanding or grinding down proud areas, such as old adhesive ridges or high screed patches.
Fife reality: older Dunfermline and Kirkcaldy properties
Older properties across Dunfermline and Kirkcaldy town centres often show more variation across a room than newer builds, sometimes from decades of patch repairs, old hearth removals or minor settlement. We treat the tolerance check as essential here rather than a formality, since assumptions based on a newer build's typical flatness don't hold.