Evidence note: This is a source-led buying guide, not a hands-on test. Seller specifications are distinguished from verified assembly measurements. No fixed decibel reduction can be promised for an underlayment in an untested floor.
STEICO 6 mm wood-fiber underlayment is offered in a nominal 90-square-foot pack of 15 boards, each 2 × 3 feet. Its suitability depends on the finished flooring, subfloor and full assembly—not simply the word “soundproofing” on a listing.
What the 90-square-foot pack tells you
| Listing detail | Practical check |
|---|---|
| 6 mm wood-fiber board | Confirm your flooring manufacturer permits this thickness and material. |
| 15 sheets at 2 × 3 ft | Nominal coverage is 90 sq ft before trimming and waste. |
| Seller describes acoustic testing | Ask for the exact report, floor assembly and test conditions. |
| Vapor-open marketing | Do not assume this replaces moisture testing or a specified vapor barrier. |
The referenced STEICO listing gives pack details. STEICO also publishes a manufacturer technical sheet for its STEICOunderfloor line. That sheet is useful context, but it must not be assumed to certify every 6 mm listing or variant.
Acoustic ratings belong to the floor assembly
Impact Insulation Class (IIC) measures impact transmission through a tested floor-ceiling assembly. Sound Transmission Class (STC) concerns airborne sound transmission through a tested partition. Seller references to ASTM E90, E492 or E2179 do not prove that one loose board will achieve the same result in every room. Slab thickness, finish layer, ceiling construction and installation all matter. Before relying on a number, obtain the dated test report and compare its construction with yours.
Moisture and click-lock warranties come first
Wood-fiber underlay is not automatically appropriate for a wet slab or every vinyl-plank system. Check subfloor moisture limits, whether a separate vapor-control layer is required, floor flatness and the flooring manufacturer’s maximum underlay thickness and compression requirements. Some systems forbid extra cushioning. Do not stack boards to mask unevenness unless the assembly instructions expressly permit it.
A sensible installation decision
- Identify the precise floor covering and read its underlay requirements.
- Confirm the board is approved over your subfloor and moisture-control method.
- Measure the room; allow for offcuts beyond the nominal 90 sq ft.
- Follow manufacturer layout, joint and edge-clearance guidance. Control dust when cutting.
- Keep the acoustic report with the project notes if a performance target matters.
When this board is worth considering
Investigate this product for a compatible floor where an approved wood-fiber intermediate layer is needed. Avoid a blind purchase for a damp substrate, an unknown click-lock floor or a job requiring a guaranteed noise reduction. Our floor-underlayment guide explains the broader choices.
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