QuietWalk Plus vs FloorMuffler UltraSeal Underlayment
By Nate Sawyer, Editor · 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.
Frequently Asked Questions
- Which underlayment is quieter, QuietWalk Plus or FloorMuffler UltraSeal?
- FloorMuffler UltraSeal on the published numbers: IIC 74 / STC 73 against QuietWalk Plus at IIC 71 / STC 66. Both are strong results - QuietWalk Plus is excellent for an upstairs room, FloorMuffler is the pick when sound isolation is the deciding requirement.
- What is the difference between QuietWalk and QuietWalk Plus?
- Our data covers QuietWalk Plus specifically - a 3 mm recycled-fiber felt with an attached vapor barrier film, GREENGUARD Gold certified and made in the USA. We do not have a verified spec sheet for the non-Plus version on file, so we will not guess at the delta. Check the manufacturer's current comparison if that distinction decides your purchase.
- Do both include a moisture barrier?
- Yes, but they achieve it differently. QuietWalk Plus uses an attached vapor barrier film so you can install directly over concrete without a separate sheet. FloorMuffler's closed-cell XLPP core is itself the barrier, with a self-sealing adhesive overlap lip joining the seams.
- Which feels better underfoot, and which suits thin LVP?
- The 3 mm QuietWalk Plus felt feels more cushioned, but that also makes it best for laminate and engineered wood rather than thin click LVP, which needs a firmer base. Neither should be stacked under flooring that already ships with an attached pad. Pricing is close: about 50 cents per square foot for QuietWalk Plus and 65 cents for FloorMuffler.