FloorMuffler UltraSeal Underlayment Review (2026)
By The DIYPicks Team · Updated July 2026
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- Floating laminate and engineered wood
- Concrete slabs needing a moisture barrier
- Maximum sound isolation
A 2 mm XLPP foam underlayment with a built-in moisture barrier, self-sealing seams, and top-tier acoustic ratings. A convenient all-in-one choice for floating laminate and engineered wood over concrete.
Pros
- Closed-cell XLPP core is its own moisture barrier, no separate poly sheet required
- Self-sealing adhesive overlap lip makes seams fast and watertight
- Class-leading IIC 74 / STC 73 acoustic numbers for serious sound isolation
Cons
- Thin 2 mm foam smooths minor imperfections but will not bridge an unlevel subfloor
- Priced above basic foam at about 65 cents per square foot
- Not intended to be added under click LVP that already ships with an attached pad
Specifications
| Thickness | 2 mm closed-cell XLPP foam |
|---|---|
| Roll Size | 100 sq ft and 300 sq ft rolls |
| Sound Rating | IIC 74 / STC 73 |
| Moisture Barrier | Integrated self-sealing overlap lip, no extra film needed |
| Compatible With | Floating and nail-down laminate, engineered, hardwood |
| Warranty | Limited lifetime residential, 10-year commercial |