Striking a Balance: Practical IIC Levels for Flooring

As multi-family living continues to thrive in Southern California, Homeowners Associations (HOAs) face the challenge of balancing resident comfort with practical regulations. A common issue sparking debate in HOA boardrooms is the appropriate sound standard for flooring installations. Excessive noise, whether from footsteps, dropped objects, or furniture movement—can disrupt the harmony of condo communities. Yet overly stringent acoustic requirements can burden homeowners with high costs, especially in communities where affordability is a priority.

At Paloma Imperial Homeowners Association in Long Beach, the board recently grappled with this issue, debating an Impact Insulation Class (IIC) standard of 75–80 for flooring installations. As a flooring expert with Floor Coverings International Surf City and a CAI member, I worked with their HOA President, Karin, and their property manager, Malena, from Dynamic Property Management Group, to craft a solution that balances acoustic performance with affordability. Here’s how HOAs can navigate this complex issue, drawing from industry standards and practical strategies.

Understanding Acoustic Standards

To set effective flooring regulations, HOAs must understand the key standards governing sound transmission in multi-family buildings:

• International Building Code (IBC): Adopted by Long Beach and most of California, the IBC sets minimum acoustic requirements for multi-family dwellings. Per Section 1206, floor-ceiling assemblies must achieve an IIC and Sound Transmission Class (STC) of 50 in lab tests (ASTM E492 for IIC, ASTM E90 for STC) or 45 in field tests (ASTM E1007 for IIC, ASTM E336 for STC). IIC addresses impact noise (e.g., footsteps), while STC covers airborne noise (e.g., voices or music).
• ASTM Standards: The American Society for Testing and Materials (ASTM) provides rigorous testing protocols. ASTM E492 and E989 measure IIC in controlled lab settings, while ASTM E1007 evaluates real-world field performance, which is critical for verifying compliance in existing buildings. ASTM E2179 introduces Delta IIC (ΔIIC), measuring the sound reduction added by flooring and underlayment over a bare concrete slab.
• LEED Considerations: For eco-conscious communities, LEED certification encourages sustainable materials. Many acoustic underlayments, such as those made from recycled rubber or felt, qualify for LEED credits due to low VOC emissions or recycled content, aligning with both environmental and budget goals.
• High-Frequency Impact Insulation Class (HIIC): A newer metric, HIIC focuses on high-frequency impact sounds (400–3,150 Hz, like heel clicks or pet nails), offering a more precise alternative to IIC for assessing flooring performance in condos.

The Paloma Imperial Case: Aiming High, Staying Practical

Paloma Imperial's CC&Rs include a 1994 carpet amendment, which mandates that all units with neighbors below them must have carpet only, with a 3/8-inch pad underneath. Many long-term owners in the building strongly believe that carpet is the only effective way to reduce foot noise from upper units. However, the building also has a fair number of newer owners, including current board members, who were hoping for more flexible flooring options. Given that previous restrictions on pets and children have been lifted, the desire for carpet alternatives has grown even stronger. For instance, Karin is also a cat mom, who is watching her carpet get shredded! Unfortunately, the board was ultimately unable to change the flooring requirement in their new rules and regulations as they had hoped. They will need to wait until they can amend their CC&Rs, which can be costly and requires a majority vote from the membership. Flooring options have evolved significantly since 1994, and the board hopes to bring the building into a more modern flooring era in the near future, without sacrificing noise issues in the building.

At Paloma Imperial, the HOA board initially proposed an IIC of 75–80, aiming for near-soundproof flooring to minimize noise complaints. However, this standard poses challenges. A typical 6-inch concrete slab, common in Long Beach condos, has a baseline IIC of about 28 without flooring. Achieving IIC 75–80 requires premium underlayment (e.g., high-density rubber or cork) and structural enhancements like suspended ceilings, which can cost $1–$2 per square foot or more. For a non-affluent community, this could make renovations financially prohibitive.

Moreover, lab-tested IIC ratings often overstate real-world performance due to idealized conditions. Field tests (per ASTM E1007) typically yield ratings 5–10 points lower, making an IIC 75–80 target impractical without costly upgrades. The human ear also struggles to distinguish differences above IIC 60–65, meaning ultra-high standards offer diminishing returns.

A Balanced Approach to Flooring Regulations

After consulting with Paloma Imperial’s management, we proposed a more achievable standard that ensures quiet living while keeping costs manageable. Here’s a framework HOAs can adopt:

• Set a Realistic IIC/STC Standard: Require floor-ceiling assemblies to achieve IIC 55 and STC 55 (lab-tested) or 50 (field-tested per ASTM E1007/E336). This exceeds IBC minimums, providing a quieter environment without excessive costs. An IIC of 55 is achievable with affordable underlayment like 3mm felt or recycled rubber, paired with flooring like laminate or carpet.
• Incorporate Delta IIC: Specify a ΔIIC of 25–30 for flooring and underlayment, tested per ASTM E2179. This metric ensures the flooring system itself contributes significantly to sound reduction, regardless of the building’s base construction. A ΔIIC of 25–30 is cost-effective and aligns with typical condo designs.
• Offer Flexible, Affordable Options: Allow a range of flooring types—laminate, luxury vinyl tile (LVT), engineered hardwood, or carpet—with underlayment meeting the IIC/STC 55 and ΔIIC 25–30 standards. Examples include:

• Roberts Felt Underlayment (3mm): IIC 67–69, ~$0.80–$1.25/sq. ft., LEED-eligible.
• Floor Muffler Ultra Seal: IIC 70+, ~$0.65–$1.05/sq. ft., mold-resistant.
• Carpet with Foam Underlayment: IIC 76, ~$1–$2/sq. ft., low-VOC certified.  
• Verify Compliance with Field Testing: Require homeowners to submit documentation of their floor-ceiling assembly (e.g., slab thickness) with flooring proposals. If compliance is uncertain, hire an acoustic consultant to conduct field tests per ASTM E1007, ensuring real-world performance meets the IIC/STC 55 standard.
• Support Affordability: Encourage bulk purchasing or HOA-negotiated discounts with suppliers to reduce costs. Avoid overly stringent standards like IIC 75–80, which could exclude budget-friendly options and burden homeowners.

Educating Your Community

Clear communication is key to successful implementation. Provide homeowners with a concise guide explaining IIC, STC, and ΔIIC, emphasizing that lab ratings don’t guarantee field performance. Share a list of approved flooring and underlayment options with their ratings and costs. For Paloma Imperial, we recommended a one-page handout to demystify acoustic standards and set realistic expectations.

Why It Matters

Adopting a balanced flooring standard, like IIC/STC 55 with ΔIIC 25–30, ensures a peaceful living environment while respecting homeowners’ budgets. It aligns with Long Beach’s building code, leverages industry standards like ASTM E1007 for verification, and supports sustainability through LEED-compliant materials. For Paloma Imperial, this approach resolved the board’s debate, offering a practical path forward as they redraft their regulations.

HOAs across Orange County can follow this model to create fair, enforceable flooring rules that enhance community living without breaking the bank. Consult with flooring experts and acoustic professionals to adapt standards to your building’s construction and use CAI resources to stay updated on best practices.

REFERENCE

IIC - Bottom of Form

From Wikipedia, the free encyclopedia (https://en.wikipedia.org/wiki/Impact_insulation_class)

Impact insulation class (or IIC) is an integer-number rating of how well a building floor attenuates impact sounds, such as footsteps. A larger number means more attenuation. The scale, like the decibel scale for sound, is logarithmic. The IIC is derived from ASTM method E989, which in turn uses a tapping machine specified in ASTM method E492.^[1]

The IIC number is derived from sound attenuation values tested at sixteen standard frequencies from 100 to 3150 Hz. "Real world" footstep noise is also generated at frequencies below 100 Hz, so the IIC value may not accurately describe the complete noise attenuation profile of a floor.^[2]

References

1.        National Research Council of Canada - Institute for Research in Construction, http://archive.nrc-cnrc.gc.ca/eng/ibp/irc/ctus/ctus-n35.html Archived 2013-02-19 at archive.today

2.        Described in California Building Code, Section 1207.9, Sound Transmission: Tested Assemblies.

Category: Sound measurements

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By Angelia Beckstrom, LEED AP,

Operations Manager for Floor Coverings International Surf City,

in collaboration from Karin Kroener-Valdivia,

HOA Property Manager, Dynamic Property Group, LLC