Floor Underlayment
A thin layer (foam, cork, felt, or rubber) installed between the subfloor and finish flooring for cushion, sound, and moisture control.
Quick answer
Floor Underlayment: A thin layer (foam, cork, felt, or rubber) installed between the subfloor and finish flooring for cushion, sound, and moisture control. Typical cost: $0.30–$1.50 per sq ft..
Why it matters
Wrong underlayment voids flooring warranties; LVP and laminate often require specific products from the same manufacturer.
Typical cost
$0.30–$1.50 per sq ft.
Pros
- • Reduces sound transmission
- • Adds moisture protection on slabs
- • Smooths minor subfloor imperfections
Cons
- • Wrong choice voids warranty
- • Adds stack height at thresholds
Common uses
- • Under floating floors, hardwood on slab, multi-family construction
Alternatives
Manufacturer-attached pad
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Frequently asked questions
- Do I need a moisture barrier?
- Yes on all slab installations; optional on dry wood subfloors with vapor-permeable finishes.
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