QuietWalk Plus vs FloorMuffler UltraSeal Underlayment
By The DIYPicks Team · Updated July 2026
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QuietWalk Plus Acoustical Underlayment
A premium recycled-felt underlayment with an attached moisture barrier and top-class IIC 71 sound rating. Ideal under laminate or engineered wood over concrete, especially in upstairs rooms where quiet matters.
| Thickness | 3 mm recycled fiber felt |
|---|---|
| Roll Size | 3 ft x 33.4 ft (100 sq ft) or 6 ft x 60 ft (360 sq ft) |
| Sound Rating | IIC 71 / STC 66 |
| Moisture Barrier | Attached vapor barrier film |
| Compatible With | Laminate, engineered hardwood, some floating floors |
| Certification | GREENGUARD Gold, made in USA |
FloorMuffler UltraSeal Underlayment
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.
| 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 |
Our verdict
These are two of the best underlayments for floating laminate and engineered wood, and both include an integrated moisture barrier. QuietWalk Plus uses a 3 mm recycled-fiber felt that feels cushioned underfoot, carries GREENGUARD Gold certification, and posts an excellent IIC 71 sound rating for about 50 cents per square foot. FloorMuffler UltraSeal is a thinner 2 mm closed-cell foam with a self-sealing seam lip and even higher IIC 74 / STC 73 acoustics for about 65 cents per square foot. Pick QuietWalk Plus for a softer, greener felt over concrete; pick FloorMuffler UltraSeal for the highest sound isolation and the fastest self-sealing seams. Neither should be added under flooring that already has an attached pad.