The IIC scale runs from roughly 25 to 80. Building codes in most U.S. jurisdictions require a minimum IIC of 50 for multi-family construction. An IIC of 60 is considered acoustically comfortable. Above IIC 70, footstep noise becomes nearly inaudible in the room below.
STC measures how well a floor blocks airborne noise — voices, music, television. The test uses a calibrated speaker producing pink noise at a known sound pressure level on one side of the assembly, with microphones measuring transmitted sound on the other side. Like IIC, the STC scale typically runs from 25 to 80.
STC and IIC are not interchangeable. A floor can have a high STC and a low IIC, which means it blocks voices well but transmits footsteps badly. Hardwood is the textbook example: a 3/4-inch solid oak floor on plywood scores STC 50–55 but IIC 40–45 without underlayment.
The decibel scale is logarithmic. A 10-point IIC increase corresponds to roughly a 10 dB reduction in transmitted sound, which the human ear perceives as halving the loudness. This is why a carpet at IIC 65 sounds dramatically quieter than a laminate at IIC 45 — not 30% quieter, but closer to 75% quieter in perceived loudness.
Delta IIC (ΔIIC) is the sound reduction the flooring and underlayment add on top of a bare concrete reference slab, so it isolates the floor’s own contribution. The large IIC numbers printed on packaging, sometimes 65 to 72, mostly reflect the slab and building structure. A Delta IIC of 14 is considered good and 24 is exceptional. A bare concrete slab alone scores around IIC 25–30.
Lab ratings also run higher than real buildings. Lab tests use a perfect slab, ideal installation and no flanking paths, so field results are typically 3–5 points lower. Field-tested ratings are labeled FIIC and FSTC, and they are the more reliable numbers when an HOA or building code sets a minimum. Many condo associations have rejected installations where the buyer relied on the packaged IIC number instead of test reports for the specific assembly.
Noise Reduction Coefficient (NRC) measures in-room sound absorption: how much echo, reverberation and ambient noise a surface removes inside the same space. IIC only measures downward transmission, so two floors with identical IIC ratings can sound very different to the people standing on them. Carpet has the highest NRC of common flooring, typically 0.40–0.50, while hardwood, laminate, tile and SPC vinyl reflect sound and make rooms feel louder. NRC rarely appears on residential flooring product pages.
Sound travels through a floor in three distinct paths: airborne transmission, impact transmission, and flanking transmission. Each flooring type interacts with these three paths differently based on its density, internal structure, and contact with the subfloor.
Material density determines how much sound energy is reflected versus absorbed. Dense, fibrous materials like wool carpet absorb high-frequency sound (above 1,000 Hz) by converting kinetic energy into heat through fiber friction. Rigid, low-mass materials like laminate reflect high frequencies and transmit low frequencies (100–500 Hz) directly into the subfloor as structure-borne vibration.
Internal cavity structure creates resonance. A laminate plank installed as a floating floor has an air gap of 1–3mm between the plank and the underlayment, and another gap between the underlayment and subfloor. This air column behaves like a drum membrane: a footstep compresses the air, which then re-radiates as a hollow “tap” sound at frequencies between 200 Hz and 800 Hz — the exact range the human ear is most sensitive to.
Hardwood eliminates the cavity by being either nailed or glued to the subfloor, which is why it sounds deeper and quieter than laminate despite both being rigid surfaces. Carpet eliminates the cavity entirely through the cushion pad, which conforms to the subfloor and absorbs vertical impact before it reaches the structure.
Carpet outperforms every hard flooring type because it is the only category that absorbs both airborne and impact noise simultaneously. Its three-layer structure — face fiber, primary and secondary backing, and cushion pad — creates a graduated impedance system. Each layer absorbs a different frequency range.
The face fiber, typically nylon, polyester, or wool, traps high-frequency airborne sound (1,000–4,000 Hz) through fiber-to-fiber friction. Wool absorbs roughly 35% more high-frequency sound than nylon at the same pile height because of its scaled cuticle structure. The cushion pad — typically 6–10 lb density rebond foam, fiber, or rubber — absorbs low-frequency impact (100–500 Hz) by deforming under load.
Pile height and density matter more than fiber type for overall noise reduction. A 1/2-inch dense plush carpet at 40 oz face weight will produce 5–8 IIC points higher than a 1/4-inch low-pile carpet of the same fiber, even with identical padding. Carpet’s acoustic benefits overlap with its thermal insulation benefits because both depend on the same property: trapped air within the fibers.
The cushion pad accounts for roughly 60% of carpet’s IIC rating. A 7/16-inch, 8 lb density rebond pad adds 8–12 IIC points compared to an unpadded installation. Rubber pads outperform foam pads at low frequencies but cost 30–50% more.
Vinyl is the second quietest flooring because its PVC core is flexible and visco-elastic — it deforms slightly under impact and converts kinetic energy into heat instead of reflecting it. Most modern luxury vinyl plank ships with a factory-attached underlayment of cork (1–1.5mm) or IXPE foam (1–2mm), which adds 5–10 IIC points compared to bare vinyl on a hard subfloor.
Vinyl flooring divides into four acoustic categories based on core composition:
The acoustic gap between LVP and SPC is real but small — typically 5–8 IIC points. SPC’s rigid core makes it sound closer to laminate than to LVP underfoot, which is why vinyl is quieter than laminate on average, but the margin depends on which vinyl subtype you choose. For installations on upper floors of multi-storey homes, LVP or WPC with cork underlayment is the acoustic equivalent of a mid-grade carpet.
Hardwood is louder than vinyl because solid wood is dense (oak averages 750 kg/m³) and rigid, with no internal damping mechanism. When a footstep lands on hardwood, the energy travels through the plank into the subfloor and into the structure as low-frequency vibration. The result is the characteristic deep “thud” of hardwood floors.
Hardwood is quieter than laminate, however, because hardwood is typically nailed or glued directly to the subfloor, eliminating the air cavity that causes laminate’s hollow “tap.” Solid hardwood transmits low frequencies (100–300 Hz) but does not amplify mid frequencies (500–1,500 Hz) the way a floating floor does.
Engineered hardwood is generally 3–6 IIC points quieter than solid hardwood at the same thickness. Its multi-layer plywood core has cross-grain construction, which means each layer’s grain runs perpendicular to the next. This breaks up vibration paths and dampens resonance, similar to how laminated glass dampens sound better than monolithic glass. The structural difference between solid and engineered hardwood is the single largest acoustic variable within the hardwood category.
If hardwood is already installed and replacement is not an option, an acoustic underlayment retrofit is impossible without removing the floor. The practical options are area rugs over high-traffic zones, ceiling treatment in the room below, and felt pads under furniture.
Laminate is the loudest of the four flooring types because three structural features compound to amplify impact noise: a rigid HDF core, a hollow floating installation, and click-lock joints that allow micro-vibration between planks.
The high-density fiberboard core has a density of 800–1,000 kg/m³ — close to oak — but unlike oak, it is bonded to nothing. The core sits on a thin underlayment (typically 2–3mm foam) above the subfloor, with two air interfaces in the assembly. Each interface acts as a sound bridge that re-radiates impact energy as airborne noise.
Click-lock joints add a secondary noise source. Under foot traffic, the tongue and groove flex slightly against each other, producing a high-frequency “creak” or “tick” that is independent of the impact noise itself. This is why laminate often sounds louder when walked on by hard-soled shoes than by bare feet, even though the impact energy is similar.
Laminate noise is not fixed. With the right underlayment and a high-density core, laminate can score IIC 60+, which approaches LVP territory. Three variables drive the improvement:
Acclimation also affects long-term noise. Properly acclimated laminate planks fit tighter at the joints, which reduces click-lock micro-vibration over the floor’s lifetime.
Vinyl is quieter than laminate in the most common real-world installation, where the vinyl has an attached IXPE or cork backing and the laminate sits on a basic 2 mm foam underlayment. The gap narrows sharply once laminate goes over an acoustic underlayment of 3 mm or more, and at that point the difference becomes a preference between laminate’s slight hollow resonance and vinyl’s more solid footfall.
The two floors separate most on footfall noise, the sound heard inside the room. Vinyl wins this by default because its softer wear layer and attached backing absorb energy at the point of impact. On impact transmission to the room below, the plank material matters far less than the underlayment, and a high-quality acoustic underlayment under laminate can match or beat vinyl with a thin attached foam backing.
| Assembly compared | Quieter result |
|---|---|
| Bare SPC on a hard subfloor vs laminate over 2 mm foam | Laminate, because the dense mineral core transmits impact efficiently; almost nobody installs this way |
| SPC with 1.5 mm IXPE backing vs laminate over standard 2 mm PE foam | Vinyl clearly in-room; comparable on transmission below |
| WPC with 1.5 mm EVA backing vs 8 mm laminate over 3 mm acoustic foam | WPC in-room; laminate may compete on IIC depending on the underlayment |
| Premium SPC or WPC with cork backing vs 12 mm laminate over QuietWalk-class underlayment | Genuinely comparable, with differences at the margins |
A 12 mm AC4 laminate over QuietWalk Plus or FloorMuffler underlayment, which reach IIC 71+ in tested assemblies, outperforms budget SPC with a 1 mm EVA backing on nearly every acoustic metric. Budget SPC with 0.5 mm EVA foam is not meaningfully quieter than laminate over cheap foam. Laminate also has one overlooked advantage: properly installed HDF joints tend to stay dimensionally stable through thermal cycles, while rigid SPC click joints can develop squeaks over an imperfectly level subfloor.
Three installation failures amplify laminate’s hollow sound: an uneven subfloor that leaves unsupported spans between planks, an underlayment too thin to fill the micro-voids between subfloor and plank, and planks not fully clicked together, leaving joint gaps that flex underfoot. Wood subfloors with squeaks or gaps over joist cavities make it worse, so fix those before installation. For upper-floor condos, use 12 mm laminate over at least 3 mm of rubber or cork underlayment rather than factory-attached foam, which is almost always too thin for association specifications.
The default ranking — carpet, vinyl, hardwood, laminate — assumes manufacturer-standard installations. Once premium underlayment is introduced, the ranking compresses significantly.
| Flooring Type | Standard Install IIC | With Premium Underlayment IIC | Net Improvement |
|---|---|---|---|
| Carpet (8 lb pad) | 60–65 | 70–75 (10 lb rubber pad) | +8–10 |
| LVP (attached pad) | 55–60 | 65–70 (3mm cork) | +8–12 |
| Hardwood (nail-down) | 45–50 | 55–60 (felt + glue) | +8–10 |
| Laminate (foam pad) | 40–48 | 55–62 (3mm cork) | +12–15 |
Laminate gains the most from premium underlayment because it starts at the bottom of the scale and has the most room to improve. Cork underlayment specifically performs better than foam at the 200–800 Hz range where laminate’s hollow resonance occurs. This is why a 12mm laminate over 3mm cork on plywood can match a basic LVP installation acoustically — though it still cannot match carpet.
Room function, subfloor type, and ceiling assembly below all change the practical answer. The acoustic ranking holds, but the appropriate floor depends on context.
For upper-floor bedrooms in multi-storey homes, carpet remains the only flooring that satisfies typical building code IIC 50 minimums without modifying the joist or ceiling assembly below. LVP with cork underlayment is the acceptable hard-floor alternative.
For concrete-slab installations on the ground floor, the IIC requirement is less strict because there is no occupied room below. The relevant metric becomes airborne (STC) and in-room reverberation. LVP and engineered hardwood with felt underlayment perform well here. Carpet remains the quietest but is rarely required.
For kitchens, bathrooms, and laundry rooms, vinyl is the only acoustically reasonable option among the four. Carpet is unsuitable in wet areas, and laminate’s HDF core swells when exposed to standing moisture.
For commercial spaces with foot traffic over 1,000 passes per day, low-pile commercial carpet or LVP with reinforced wear layer is standard. Hardwood and laminate are acoustically and structurally unsuitable at this traffic level.
Flanking noise is sound that bypasses the floor assembly entirely through walls, pipes, ducts or structural connections, and no flooring material can stop it. In timber-frame homes with shared walls, flanking through the wall studs can exceed the noise passing through the floor. The fixes are structural: resilient channels on the ceiling below, acoustic sealant around penetrations and mass-loaded vinyl on shared walls. If a floor meets or exceeds its IIC requirement and noise still travels, flanking is the most likely cause.
Underlayment material also decides whether a floor stays quiet. Thin foam compresses permanently under load within a few years, and the IIC on the package reflects new foam. Cork and rubber keep their structure: 3 mm of cork often outperforms 6 mm of foam, and 6 mm of cork gives roughly the same sound reduction as 4 mm of solid rubber. Rubber is strongest for long-term impact noise; cork is better for airborne noise and adds thermal insulation.
Area rugs are the most flexible in-room fix for any hard floor. A rug covering 60–70% of a hard-floored living room significantly reduces reverberation, and a large rug over a dense pad can add 10–20 IIC points to a hardwood assembly by absorbing impact at the surface.
The quietest flooring is carpet, which absorbs both airborne and impact noise through its fiber-and-pad system and scores IIC 60–75 in standard residential installations. Vinyl is the quietest hard flooring, with LVP and WPC reaching IIC 60–70 with attached underlayment. Hardwood is quieter than laminate but louder than vinyl, scoring IIC 45–55 in nailed or glued installations. Laminate is the loudest at IIC 40–50 in standard installations, though it can be brought into LVP territory with 3mm cork underlayment and a 12mm plank.
If quietness is the only consideration, carpet wins. If the floor must be hard, LVP with cork underlayment is the closest acoustic match to carpet. If the floor must be wood, engineered hardwood with felt underlayment is the quietest hardwood option. If laminate is the only option for budget or design reasons, the highest-impact upgrade is the underlayment, not the plank itself.
An IIC of 60 is considered acoustically comfortable for residential rooms. IIC 50 is the building code minimum for multi-family construction in most U.S. jurisdictions. IIC 70 and above is nearly silent in the room below.
Yes. A 12mm laminate plank scores 4–7 IIC points higher than an 8mm plank of the same brand because the higher core mass shifts the resonant frequency below the human ear’s most sensitive range.
Yes, by 3–6 IIC points on average. The cross-grain plywood core breaks up vibration paths and reduces resonance compared to solid wood.
No. Hardwood with the best underlayment and rugs reaches roughly IIC 60. Standard carpet starts at IIC 60 and reaches IIC 75. The gap is structural — hardwood cannot absorb airborne noise the way carpet fibers do.
Laminate is installed as a floating floor with two air interfaces — between the plank and underlayment, and between the underlayment and subfloor. A footstep compresses these air columns, which then re-radiate as a “tap” at 200–800 Hz, the frequency range the human ear is most sensitive to.
James Miller is a seasoned flooring contractor with years of hands-on experience transforming homes and businesses with high-quality flooring solutions. As the owner of Flooring Contractors San Diego, James specializes in everything from hardwood and laminate to carpet and vinyl installations. Known for his craftsmanship and attention to detail, he takes pride in helping clients choose the right flooring that balances beauty, durability, and budget. When he’s not on the job, James enjoys sharing his expertise through articles and guides that make flooring projects easier for homeowners.
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