(415) 864-4440
Serenity Underlay

Serenity 9mm Acoustic Underlayment Roll

The Serenity 9mm Underlay Roll adds mass and thickness over the 6 mm sheet — the balanced pick when a floor project needs more impact isolation but still has to keep finished-floor buildup in check. Each 4' × 25' roll covers 100 sq ft and pairs cleanly with LVT, engineered wood, and floating hardwood floors.

  • 100 sq ft per roll: 4 ft × 25 ft continuous roll — sizes cleanly for typical bedroom, living-room, and home-office layouts.
  • 9 mm build-up: Balanced thickness that adds real acoustic mass without pushing transition heights into problem territory.
  • 1.1 lb / sq ft mass: More loaded mass than the 6 mm sheet — better mid- and low-frequency airborne performance across the underlayment layer.
  • R-0.30 thermal: Slight thermal benefit — noticeable underfoot over slab-on-grade or cold subfloors.
$259.99
/ roll

Online orders up to 500 rolls. For anything larger, call (415) 864-4440 and we'll price the project with you.

Freight shipments include a $100 freight-and-handling charge.

Authorized Serenity DealerUnderlayment for floating & glued floorsLocal pickup: SF, San Leandro, LA
Product Specs

9mm Roll Specifications

Application
Floating & glued-down finished floor decoupling
Roll size
4 ft × 25 ft (100 sq ft)
Thickness
9 mm
Mass
1.1 lb / sq ft
Thermal resistance
R-0.30
Composition
Recycled rubber composite
Compatible finishes
LVT, engineered wood, laminate, floating floor
Quantity Calculator

9mm Roll Project Calculator

Enter your floor square footage — we'll estimate the number of 9mm Roll rolls needed (each roll covers 100 sq ft).

Coverage is 100 sq ft per roll. Add a 10% buffer for seams, cuts, and re-work.

Estimated Materials
—Underlay rolls needed
Indicative only. Final quantities vary by framing spacing and access.
Sound Performance

IIC Gauge

Compare how the 9mm Roll performs across assembly tiers. Select an assembly below to see the resulting IIC score.

Serenity 9mm + double subfloor with Green Glue between layers.

IIC58
080
What the score means
  • STC 30-39: Loud speech clearly audible next room.
  • STC 40-49: Loud speech muffled — normal residential wall.
  • STC 50-59: Loud speech barely audible; suitable for offices & multi-family.
  • STC 60+: Approaches studio-grade isolation.
Product Comparison

How 9mm Roll compares

ModelThicknessCoverageMassBest For
6mm Roll6 mm120 sq ft / roll0.9 lb / sq ftLow-profile retrofits
9mm Rollthis9 mm100 sq ft / roll1.1 lb / sq ftBalanced acoustic + build-up
12mm Roll12 mm80 sq ft / roll1.1 lb / sq ftHighest impact isolation
Downloads

Data Sheets & Guides

Serenity Underlay — Data Sheets Library
FAQ

9mm Roll — Common Questions

The 9mm is the balanced pick — same rubber-composite formula but with more mass and thickness. Step up from the 6mm when the room below is a bedroom, media room, or office and the finished floor is a hard surface (LVT, engineered wood).