Check compatibility
Underlay must suit the floor type, subfloor and installation method. Some products already include a backing and should not receive a second underlay.
Moisture and sound
Concrete subfloors may require an approved vapour barrier. Acoustic claims depend on the complete floor build-up, not only the underlay thickness.
Calculate roll coverage
Use floor area plus a modest cutting allowance and compare it with usable roll coverage. Overlaps and upstands can increase the requirement.
Practical checklist
- Read both flooring and underlay instructions.
- Do not block required expansion gaps.