In a Chicago condo, your floor is your neighbor’s ceiling. When you replace carpet with wood or tile, or open a wall, you change how much sound travels between homes, and many associations regulate that through their declaration and rules, for example by requiring approved sound underlayment or a minimum sound rating under hard floors. The safest path is to get your building’s written requirement first, design the floor and wall assemblies to meet it, and keep the test data your board may ask to see.
This guide explains the ratings, the materials and the approvals, so you can plan high-rise condo remodeling in Chicago without surprises downstairs.
Why Sound Matters When You Remodel a Condo
Sound moves through a building in 2 ways. Airborne sound, such as voices or a television, travels through the air and then through walls and floors. Impact sound, such as footsteps, starts as a vibration in the structure itself. The National Research Council of Canada (NRC), a long-standing building-science reference, draws exactly this line in its building digests.
Carpet and pad used to soften footsteps at the surface. A hard floor removes that cushion, so the sound control has to move underneath it.
Sound also finds side routes. Building scientists call these flanking paths: sound that travels around a wall or floor through the connected structure, through gaps, or along pipes. The NRC notes that in a poor design, flanking can carry more sound energy than the direct path, and that floors are especially prone to impact sound carried through their supporting structure. That is why a good product can still disappoint when the details around it are wrong.
What IIC and STC Ratings Mean
IIC: Impact Sound Through Floors
Impact Insulation Class (IIC) rates how well a floor and ceiling assembly blocks impact sound. In the laboratory test, a standardized tapping machine strikes the floor above while sound levels are measured in the room below (ASTM E492, classified under ASTM E989). According to the NRC, the higher the IIC, the better the floor system.
STC: Airborne Sound Through Walls and Floors
Sound Transmission Class (STC) rates how well a wall or floor blocks airborne sound. It is derived from laboratory measurements of how much sound an assembly stops across a range of frequencies (ASTM E90, classified under ASTM E413). Here too, the larger the number, the better the assembly.
Lab Ratings and Field Ratings
Lab numbers describe an assembly under controlled conditions. Field tests measure the finished rooms, including flanking paths and any construction defects, and they carry their own labels, which vary by test standard and code edition: Hardwood Floors lists FIIC, AIIC and FSTC, and recent IBC-based codes use NNIC and NISR. Hardwood Floors, the National Wood Flooring Association’s magazine, cautions that field tests are accurate only for the site where they were performed.
For context, the same article reports that model building codes such as the International Building Code set minimums of 50 for both IIC and STC, or 45 when field tested. Codes like this govern the floors and walls between dwelling units. Whether a code figure applies to a renovation inside an existing Chicago building is a question for your design team and the city, and your association’s rule is a separate document that may ask for more.
Association Rules for Hard Flooring
An Illinois condominium attorney, writing in the Daily Herald in July 2026, noted that neither the Illinois Condominium Property Act nor most municipal building codes require carpet in upper-floor units. The rules usually come from the association.
According to that column, many declarations contain flooring provisions, which may require hard-surface flooring to include approved sound-deadening underlayment, or a share of the flooring, often 80%, to be carpeted, excluding kitchens and bathrooms. The same column says boards stand on firmer legal ground with reasonable rules that:
- set minimum sound-insulation standards;
- require approval before flooring is replaced;
- require acoustical underlayment that meets specified IIC and STC ratings.
Hardwood Floors adds that many associations write their own minimum standards into their covenants, and that these often go beyond the code minimums. Some also require acoustical foam in the expansion gap at the edge of a wood floor and acoustical sealant.
Treat all of this as common patterns to confirm, not as your building’s rule. Before you choose a floor, ask your property manager for:
- the declaration, bylaws and current rules covering flooring and alterations;
- the required rating, and whether it is a lab rating, a field rating or a list of approved products;
- whether approval is needed before the old floor comes out;
- any carpet percentage or room-by-room limits.
Our guide to obtaining condo board approval for a Chicago remodel walks through the wider approval package.
Underlayment Options for Wood and Tile
Common Underlayment Materials
Acoustical underlayments are made from materials such as recycled rubber, synthetic cork and wood composites. They are usually designed for a specific application, because a glue-down, floating or nailed floor each asks something different of the layer beneath it.
Some systems use an acoustical adhesive instead of a separate mat. Hardwood Floors notes that these still need third-party testing and the specified trowel. It also gives one rule every wood installer should follow: never nail through an acoustical underlayment, because doing so compromises its rating.
Reading a Delta IIC Number
Underlayment test reports often show a Delta IIC, the improvement a product adds over the bare structure. Hardwood Floors explains that it is found by subtracting the IIC of a nominal 6-inch bare concrete slab from the IIC of the tested assembly.
Why Tile adds 2 cautions. A product’s Delta IIC does not carry over to a different floor construction: a mat tested over 6-inch concrete will not deliver the same value over a wood floor. And Delta IIC numbers are not cumulative when you stack several sound control products. The finish matters too, since the type and thickness of tile or stone can change the result. Ask for test data that matches both your finish and a structure like yours.
What Underlayment Will Not Do
Sound control underlayments typically have marginal or no effect on STC, according to Why Tile, which notes that STC is largely set by the solid mass of the structure. If voices or a television are the complaint, the answer lies in the walls and ceiling, not the floor mat.
Walls and Ceilings: Mass, Isolation and Sealing
Opening a wall is a chance to make it quieter. It is also a chance to make it louder, if the new work ties the 2 sides together or leaves gaps.
Walls
The NRC’s digest on sound transmission names mass per unit area as the most important factor in blocking airborne sound. In a wall with 2 faces, the next lever is isolation: the NRC compares a rigid connection between the faces to an electrical short circuit. Assemblies that keep the faces apart include resilient channels, staggered studs and double rows of studs.
Insulation in the cavity helps most when the faces are isolated. In the NRC’s examples, sound-absorbing material raised the STC by about 8 points in the walls built for sound control, but by only about 3 points in a common stud partition with drywall attached directly to both sides, because the studs carry sound straight from one face to the other.
Openings undo good work. An earlier NRC digest warns that cracks and holes at joints or around service outlets can spoil an otherwise excellent wall, so outlets, pipe penetrations and the edges of the wall all need sealing.
Ask early whether the wall you want to change sits inside your unit or is shared with a neighbor, because the answer can change who has to approve the work. The same principles apply to a home office or media room in any interior remodeling in Chicago, condo or not.
Ceilings
The ceiling below a floor is part of its rating. Why Tile gives a drop ceiling with a deep plenum as one way to add sound control, and the NRC notes that a suspended ceiling can help a floor reach a satisfactory impact rating, though it calls a floating floor generally more successful because it keeps impact vibration out of the main structure. In a condo, the ceiling under your floor is in your neighbor’s home, so improving your own ceiling mainly helps with noise from the unit above you.
Plumbing Noise
Pipes and fixtures can carry sound from one home to the next. NRC guidance warns that service pipes can form a direct path between units, recommends supporting them resiliently and keeping them off walls where quiet matters, and advises choosing quiet fixtures.
An acoustic consultant writing in the Journal of Light Construction explains that water running through PVC drain pipe is louder than through cast iron, mostly because PVC has less mass, and that pipe insulation alone typically absorbs only 2 to 3 dB. The article’s recommendations:
- avoid rigid connections between drainpipes and framing;
- use neoprene pads where hangers attach piping to joists or studs;
- seal the openings where pipes pass through framing, since holes as small as 1 inch can reduce the effectiveness of soundproofing.
If your remodel moves or adds fixtures, include the pipe routing and isolation details in the plans you submit to the association.
Testing and Documentation Your Building May Ask For
The rating belongs to the whole assembly. Hardwood Floors makes the point directly: no single component can meet a building’s requirement on its own, and the right system depends on the type of flooring, the substrate, the concrete thickness, the ceiling suspension, the framing and the entire floor and ceiling assembly.
Requirements differ by building, so ask what yours expects. Depending on the rule, a sound-control submission might include:
- the underlayment’s test report from an independent lab, ideally for an assembly like yours;
- a description of the full assembly, from the finish floor down to the ceiling below;
- edge details, such as perimeter isolation and sealant;
- a field test after installation, if the rule is written as a field rating.
Why Tile advises that final field ratings come from on-site testing by trained, licensed personnel, and points readers to a NIST search tool for certified labs. Keep every report with your approved plans. Hardwood Floors warns that non-compliance can be extremely costly and often ends in litigation.
How a Design-Build Team Handles Approvals
Sound control works best when it is designed in, not added after the finishes are chosen. In a design-build model, the team that selects the floor and plans the walls also builds them, so the assembly the board reviews is the assembly that gets installed.
At Areté, design and construction sit under one roof, with an in-house interior design team, and each project is run by a Project Manager. For a condo, that means the floor you choose, the assembly behind it and the paperwork your building asks for are planned together, rather than reconciled at the end.
For more on the condo process, see what to expect during a Chicago condo remodel, or our ideas for soundproofing a busy Chicago kitchen. If you are planning high-rise condo remodeling in Chicago, start with your building’s rules and let the acoustics shape the design.
Frequently Asked Questions
Does Illinois Law Require Carpet in a Condo?
Not according to the July 2026 Daily Herald column by an Illinois condominium attorney cited above. Your declaration and board rules may, and many declarations include flooring provisions such as approved sound underlayment under hard floors.
What IIC Rating Does My Chicago Building Require?
It depends on your building. Ask for the written rule and whether it is a lab or field rating. For reference, model codes set 50 between units, or 45 in the field, and associations can set stricter standards.
Is a Higher IIC or STC Rating Better?
Yes. On both scales, a larger number means the assembly blocks more sound.
Will a Sound Underlayment Stop My Neighbors From Hearing Voices?
Not much. Underlayments mainly reduce impact sound and typically do little for STC. Voices are an airborne problem, handled by mass, isolation and sealing in the walls and ceiling.
Can I Stack 2 Underlayments for a Higher Rating?
Do not count on it. Delta IIC numbers are not cumulative across multiple sound control products, so rely on a test of the assembly you plan to build.
Does Tile Need Different Test Data Than Wood?
It should have its own. The type and thickness of tile or stone can change a product’s Delta IIC, and the type of flooring is one of the variables that decides which sound control system fits, so ask for data that matches the floor you are installing.
Planning a new floor or a wall change in your building? Contact Areté to talk through your building’s rules and your design.
