What mm underlay is best for stairs?

We've done some DIY flooring jobs myself in the past, but we've always avoided stairs ourselves. I want to give them a shot this time around, but just a bit unclear on the mm of the underlay or whether underlay should even be used?

Asked by Akinfolayan on 5th Mar 2026
Expert Trade Answers
"I would suggest using a dense 9mm foam underlay on your stairs . It will give you the comfort but without to much movement. Make sure you staple it on well so it doesn't slip"
Answered on 5th Mar 2026 - Member since May 2020 - report
"For stairs you should use a firm, dense underlay rather than a thick soft one.

Carpet stairs: usually around 6–9 mm dense stair underlay.

Laminate or wood stairs: normally no underlay, as boards are usually fixed or glued for stability.

Stairs need a stable and secure base due to heavy foot traffic."
Answered on 5th Mar 2026 - Member since Feb 2026 - report
"I don't use that on the stars for wood flooring or laminate"
Answered on 23rd Mar 2026 - Member since May 2022 - report
"HI , So a good dense 9mm underlay with carpet grippers would make the new carpet last and feel thick underfoot.
i would recommend getting it fitted professionally though ."
Answered on 28th Mar 2026 - Member since Aug 2025 - report
"Good morning.
A standard gripper is 9mm thick so generally you'd want to stick to the same thickness to keep maximum carpet on the spikes of the gripper.
Regards Jack Snappy Flooring"
Answered on 16th Mar 2026 - Member since Mar 2026 - report
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