STC Requirements
Calculator
Direct answer: for the stated IBC 2021 dwelling and sleeping-unit separation scope, the built-in target is laboratory STC 50 or field NNIC 45. Choose the matching test basis below, then compare it with a documented rating. For every other project type, enter a target verified from the applicable owner criteria, contract, regulation, or sector standard.
Who it is for: architects and acoustical consultants checking a documented acoustic test rating against one confirmed target at construction documents. It does not select an assembly, predict field loss, or determine requirements for schools, healthcare, offices, hotels, façades, impact sound, or local amendments.
| Adjacency | Target | Source |
|---|---|---|
| Dwelling or sleeping unit to another unit, public or service area (walls, partitions, floor/ceiling), airborne | STC 50 lab (ASTM E90) or NNIC 45 field (ASTM E336) | IBC §1206.2 |
| Floor/ceiling between those spaces, impact sound | IIC 50 lab (ASTM E492) or NISR 45 field (ASTM E1007) | IBC 2024 §1206.3 |
| Video-conference and training rooms (federal offices) | STC 53 minimum | GSA Sound Matters, 2012 |
| Conference rooms and executive offices needing confidential speech privacy | STC 45 minimum | GSA Sound Matters, 2012 |
| Private offices needing normal speech privacy | STC 40 minimum | GSA Sound Matters, 2012 |
The GSA values are the agency's design guidance for federal offices, not code minimums. We hold no cited source for hotel room-to-room, school classroom (the 2024 IBC sends enhanced classroom acoustics to ICC A117.1 §808, not to an STC number) or hospital patient-room targets, so none is listed: enter the verified target for your project in the calculator above. The IBC rows are read from the 2024 text; the built-in IBC option above keeps its 2021 reference, and the 2024 airborne text gives the same 50 and 45.
How to use this calculator
The formula
A nonnegative difference means the entered rating equals or exceeds the selected numerical target. It does not establish assembly construction, installation quality, field performance, or whole-project compliance.
Worked example
When this estimate will be off
- The built-in IBC condition applies only to the §1206.1/§1206.2 dwelling and sleeping-unit separation scope.
- The calculator does not predict a rating from materials and does not recommend an assembly.
- Impact sound, IIC/NISR, exterior OITC, low-frequency noise, mechanical vibration, and background-noise criteria are excluded.
- A user-entered target is not validated as a legal, contractual, healthcare, education, or certification requirement.
Frequently asked questions
A common mistake: The built-in IBC condition applies only to the §1206.1/§1206.2 dwelling and sleeping-unit separation scope.
No. Enter a target verified from the applicable owner criteria, contract, regulation, or sector standard.
Not under the built-in IBC option. The code text distinguishes laboratory STC 50 from field NNIC 45.
No. Applicability, documentation, construction, penetrations, installation, and amendments remain separate checks.
STC is a laboratory rating of an assembly under ASTM E90. A field test under ASTM E336 is reported as NNIC and is compared with its own number: the IBC asks for STC 50 in the laboratory or NNIC 45 in the field for dwelling-unit separations, so the two are not interchangeable.
The IBC sets none for ordinary offices. GSA Sound Matters recommends STC 53 for video-conference and training rooms, STC 45 where conference rooms and executive offices need confidential speech privacy, and STC 40 for private offices with normal speech privacy. Owner or tenant criteria can set other values.
We hold no cited requirement for this pair. Use the criteria in the school’s program, the adopted code and ICC A117.1 §808 for classroom acoustics, and enter the verified target in the calculator above.
The table above lists the targets we can cite: the IBC dwelling and impact figures and the three GSA office values. Hotel, school and healthcare targets are not listed because we hold no cited source; verify them against your project criteria.
Sources
- GSA — Sound Matters: How to Achieve Acoustic Comfort in the Contemporary Office (2012) — Walls checklist: STC 53 video-conference and training rooms, STC 45 confidential conference and executive areas, STC 40 private offices.
- ICC — 2024 IBC §1206.2 and §1206.3 — Airborne sound STC 50 (ASTM E90) or NNIC 45 (ASTM E336); impact sound IIC 50 (ASTM E492) or NISR 45 (ASTM E1007) for dwelling and sleeping-unit separations.
- ICC — 2021 IBC §1206.2 — Airborne-sound requirement for the scoped dwelling and sleeping-unit separations: laboratory STC not less than 50 under ASTM E90, or field NNIC not less than 45 under ASTM E336.
Sources and review record
Sources and method basis
- IBC 2021 §1206.1 and §1206.2; ASTM E90 laboratory STC and ASTM E336 field NNIC references
- https://codes.iccsafe.org/
Limitations
- Built-in targets cover only the stated dwelling/sleeping-unit separation scope; assembly prediction, impact sound, other sectors, local amendments, and compliance are excluded.
This free STC Requirements Calculator is built and maintained by DataDrivenAEC, using the relevant codes and standards. It does not substitute for professional judgment.