PET Felt Clouds Thickness and Density Options David Hurtado Oct 9, 2026 Table of Contents A general contractor on a corporate build-out calls two weeks before ceiling trades mobilize: the submittal for the open-plan floor still just reads “PET felt ceiling cloud,” with no thickness or density callout, and the acoustic consultant’s performance spec and the architect’s visual rendering clearly assume two different products. Nobody caught it until the cut sheets landed side by side. We see this gap on nearly every cloud submittal that crosses our desk. “PET felt” describes the raw material, not the finished panel’s acoustic behavior, and two clouds cut from the same 60% recycled PET felt core can land at nearly opposite ends of the performance range depending on how thick and how dense that core actually is. A reception lobby that wants a sculptural, low-absorption accent and a call center fighting a reverberation complaint can both be specified in “PET felt,” and both can fail their intended purpose if thickness and density get treated as a single, interchangeable spec line. That mismatch is almost always a sequencing problem, not a product problem. Once a design team separates thickness from density and matches each to what the room actually needs, the rest of the cloud selection — shape, finish, suspension pattern — falls into place quickly. Thickness and Density Are Two Different Specs Thickness is the easiest number on a cut sheet to read and the easiest one to misuse. It tells an installer how much clearance a panel needs above a sightline and roughly how much material is in the panel, but it says nothing on its own about how that panel performs acoustically or how it behaves visually once it is hung. Density — how tightly the polyester fibers are compressed and felted together per unit of volume — is the variable that actually governs rigidity, drape, and a meaningful share of sound absorption. A thick panel pressed at low density can still sag at the corners; a thin panel pressed at high density can hold a crisp, almost rigid edge. Treating these as one spec is how a submittal ends up with the right gauge and the wrong feel, or the right look and the wrong NRC. Pulling them apart early lets a designer and an acoustic consultant each get what they are actually asking for. Standard Thickness Tiers in PET Felt Ceiling Clouds Most PET felt ceiling cloud lines are built around two or three thickness tiers rather than a continuous range, largely because felting equipment is tuned to specific gauges and because fabricators need repeatable results across large production runs. Thin Profiles: Roughly 9mm to 12mm A 12mm recycled PET felt panel is the workhorse gauge for most cloud programs. It is light enough to fabricate into faceted, waffle, and curved geometries without the material fighting the form, and it carries enough body to hold a clean edge on a framed or stacked cloud. For spaces where the cloud’s visual role — breaking up a flat ceiling plane, adding color, softening a hard lobby — matters as much as its acoustic role, this tier is usually the right starting point, and it is the gauge most readily available across the widest color and finish selection. Heavy Profiles: 24mm and Up Doubling the gauge to an extra-thick recycled PET felt panel changes the math on both ends: there is simply more fiber mass available to absorb mid- and high-frequency sound energy, and the panel reads visually heavier and more substantial once it is suspended. That extra mass is also why this tier gets reserved for rooms with a real noise problem to solve — open floor plates with dense desk clusters, dining rooms with hard floors and glass, gymnasiums and natatoriums — rather than for purely decorative applications where the thinner gauge already does the job. Density Is the Variable Hiding Behind the Thickness Number Two panels can share an identical thickness and still behave like different products once density is factored in, because density determines how much actual fiber is packed into that thickness and how the fibers are bonded to each other. Lower-Density Cores: Softer Drape, Lighter Visual Weight A lower-density felt core behaves more like a textile and less like a board. It drapes slightly at unsupported edges, conforms more readily to curved or faceted tooling, and reads as visually soft against a ceiling plane. That softness is an asset on organic or sculptural cloud shapes where a crisp, board-like edge would look out of place, but it is a liability on long spans or cantilevered cloud sections, where the same low-density material can develop a visible sag over time if it is not framed or backed. Higher-Density Cores: Rigidity and Shape Retention Compress the same fiber volume tighter and the panel starts to behave like a semi-rigid board: it holds a flat plane without a frame, resists edge curl in humid or variable-temperature environments, and tolerates longer unsupported spans before it needs an intermediate support point. The tradeoff is weight and, in some constructions, a slightly reduced mid-frequency absorption efficiency per unit of material compared with a looser, lower-density felt of the same thickness, since tightly bonded fibers leave less open pore structure for sound waves to dissipate into. How Thickness and Density Together Drive NRC Performance Noise Reduction Coefficient is where thickness and density stop being separate variables and start acting as one combined factor. A thin, low-density panel absorbs a meaningful amount of mid- and high-frequency sound but does relatively little for the low end. Add thickness, density, or an air gap behind the panel, and low-frequency absorption improves because the sound wave has more material — or more open space backed by material — to travel through before it reflects. Panel ProfileTypical ThicknessRelative DensityWhere It Performs BestBest-Fit Use Case Decorative accent~9mmLowMid-to-high frequency, light overall absorptionLobbies, retail displays, branding moments Standard felt cloud12mmLow-to-mediumBalanced mid-frequency absorptionOpen offices, meeting rooms, corridors Extra-thick felt cloud24mmMedium-to-highExtended low-to-mid frequency absorptionCall centers, dining halls, gymnasiums, high-reverberation spaces Rigid high-density panel12mm-24mmHighShape retention over absorption efficiencyLong cantilevered spans, exposed-edge sculptural clouds None of these tiers exists in isolation from the others; a project with both a sculptural lobby cloud and a performance-driven open-office installation will usually end up specifying two different gauges from the same product family rather than forcing one thickness to do both jobs. Weight and Suspension-Load Implications Every jump in thickness or density adds mass, and that mass has to be carried by whatever grid, cable, or rod system is holding the cloud off the structural deck. A ceiling contractor sizing a suspension layout for a dense, 24mm cloud field needs different anchor spacing and cable-gauge assumptions than one hanging a field of thin, low-density accent panels, even if the two layouts look nearly identical on an architectural reflected ceiling plan. This is also where how a suspended ceiling material’s weight affects the supporting system becomes a structural question as much as an acoustic one, particularly on retrofit projects where the existing deck wasn’t designed with a dense acoustic cloud field in mind. Getting the suspension engineering wrong in either direction causes real problems: oversizing the hardware for a light, thin-gauge cloud adds unnecessary cost and visual bulk above the panel line, while undersizing it for a dense, thick panel risks sag, uneven reveals between adjacent clouds, or a callback once the panels settle under their own weight. Matching Thickness and Density to the Space The fastest way to narrow a cloud spec is to start from the room’s actual noise problem rather than from a catalog page. A space with hard, parallel surfaces and a documented reverberation or speech-intelligibility complaint should drive the decision toward the thicker, denser end of the lineup, even if that means a plainer visual result. A space where the ceiling is doing more design work than acoustic work — a reception area, a branded corridor, a retail vignette — can usually run on the thinner, lighter tier without giving up anything the room actually needs. It also helps to think about thickness and density relative to the other ceiling-mounted acoustic element already in the project, since the tradeoffs between baffles and clouds as acoustic treatments often come down to the same thickness-versus-coverage math: a field of thin clouds spread across a ceiling plane and a smaller number of thick, dense clouds concentrated over a noise source can hit a similar overall NRC target through very different material choices. The full lineup of suspended cloud shapes and configurations gives a sense of how many of those geometries are available once the thickness and density decision is locked in, and teams still weighing felt against other core materials can compare how different ceiling acoustic materials perform on cost and maintenance before the gauge gets written into the spec. Any NRC figure used to compare those options only holds up when it was measured under the mounting conditions set out in the ASTM C423 reverberation-room test method for sound absorption, since suspension height and the air gap behind a cloud change the result nearly as much as the felt itself. Conclusion Thickness tells an installer how much room a panel needs; density tells a specifier how that panel will actually perform and hold its shape once it is in the air. Separating the two early — and matching each to the room’s real acoustic demand rather than defaulting to whatever gauge shows up first in a sample box — is what keeps a cloud submittal from turning into a late-stage surprise. Once that decision is made, the rest of the selection process, from shape to finish to suspension hardware, moves considerably faster. FAQ Is a thicker PET felt cloud always a better acoustic choice than a thinner one? Not automatically. A thicker, denser panel generally extends absorption further into the low-frequency range, but a thin panel at the correct density can outperform a poorly matched thick one for mid- and high-frequency speech clarity. The right choice depends on which frequency range the room’s noise complaint actually falls into, not on thickness alone. Can thickness and density be mixed within the same ceiling cloud layout? Yes, and on larger floor plates it is common. A denser, thicker tier can be concentrated over the loudest zones — near equipment, dense desk clusters, or hard-surfaced gathering areas — while a lighter, thinner tier covers the rest of the ceiling plane for visual consistency without the added weight and cost everywhere. Does a higher-density PET felt panel cost more than a lower-density one at the same thickness? Generally yes, since more fiber is compressed into the same panel area and the felting process takes longer to produce a tighter bond. The added cost is usually justified only when the project needs the rigidity or extended low-frequency absorption that density provides, rather than as a default upgrade. How do I know if a space needs a thin decorative cloud or a thick acoustic cloud? A documented reverberation time, a speech-intelligibility complaint, or a hard-surfaced room with no other absorptive finishes are all signals that point toward the thicker, denser tier. A space with carpet, upholstered furniture, or other absorptive surfaces already in place can often meet its acoustic goals with a thinner panel used mainly for visual effect. Does panel thickness affect how a PET felt cloud is suspended? Yes. Thicker, denser panels carry more weight and typically need closer suspension-point spacing, heavier-gauge cable or rod, and in some cases an internal frame to prevent long-term sag, while thinner, lighter panels can often be hung with a simpler suspension layout.