The HOA Flooring Approval Kit

The test reports, assembly ratings, and cover letter your HOA wants — packaged and ready to submit.

“My HOA requires IIC 72. Which floor do I buy?” We hear it every week. Here is the honest answer: no flooring product carries an IIC 72 rating on its own, because IIC measures the entire floor-ceiling assembly — your slab, the ceiling below, and the floor working together. What a flooring system can honestly claim is how much it adds. Ours adds a lot, and we have the lab reports to prove it.

We have already published the deep guides — how to achieve an IIC 72 rating in your condo, what to do when your HOA requires IIC 72, and why an honest IIC 50–55 is already excellent. This page is the practical half: the documents.

Download the Kit (ZIP)

IIC, STC, and ΔIIC in plain language

Most HOA flooring rules reference one of three numbers. They are not interchangeable, and knowing the difference is the fastest route to an approval:

IIC (Impact Insulation Class) rates how well a floor-ceiling assembly blocks impact sound — footsteps, dropped objects, chair legs. It is measured on the whole structure: slab, ceiling, insulation, and floor covering combined. A bare 6-inch concrete slab typically tests around IIC 27 on its own.

STC (Sound Transmission Class) is the same idea for airborne sound — voices, TV, music. Associations sometimes quote STC minimums alongside IIC.

ΔIIC (Delta IIC, ASTM E2179) measures only the improvement the flooring and underlay contribute, with the slab’s contribution mathematically removed. It is the one number that travels from building to building, and the only fair way to compare two products. As a rule of thumb: ΔIIC 14 is a good acoustic floor; ΔIIC 20 is excellent. Thin foam underlays typically contribute single digits to low teens.

ΔLw (EN ISO 717-2) is the European equivalent — impact sound reduction in decibels. Our European-made lines (Swiss Design cork, TechSlate) are rated this way: 18–19 dB.

When your CC&Rs say “IIC 50” or “IIC 72,” they are describing the finished assembly in your unit — which is why this kit contains both the per-product test statements and a cover letter that shows the assembly math.

The numbers, on the record

Every figure below comes from a document we host. The source file for each row is linked — the same files that are inside the kit.

Product / system	Tested result	Standard	Source document
3mm cork underlayment	IIC 39 / STC 40 (6″ concrete, no suspended ceiling); IIC 53 / STC 54 (with suspended ceiling)	Assembly test	Test statement (PDF)
6mm cork underlayment	IIC 50 / STC 51 (no ceiling); IIC 64 / STC 65 (with suspended ceiling)	Assembly test	Test statement (PDF)
12mm cork underlayment	IIC 75 / STC 76 (no ceiling); IIC 89 / STC 90 (with suspended ceiling)	Assembly test	Test statement (PDF)
12mm cork floating flooring (e.g. Silver Birch)	IIC 55 (5.5″ concrete, no suspended ceiling); 19 dB impact noise reduction (ΔLw)	ISO 140-8	Test report (PDF)
11mm Swiss Design cork floating (e.g. Sandstorm)	18 dB impact sound reduction (ΔLw)	EN ISO 717-2	Test report (PDF)
10mm cork floating lines (Terrazzo, Sustainazzo, Shoreline, Venetian)	19 dB impact sound reduction (ΔLw), tested at 11mm	EN ISO 717-2	Test report (PDF)
Grano 10mm cork floating	18 dB impact sound reduction (ΔLw)	EN ISO 717-2	Figure per product listing
Swiss TechSlate 7.5mm (e.g. Bright Stone)	Approx. 19 dB impact sound improvement	EN ISO 717-2	Figure per product listing
6mm glue-down cork tile	18 dB impact sound reduction	—	Figure per product listing
11mm cork floating floor + 6mm cork underlayment	ΔIIC +20	ASTM E2179 (NGC report 7013034)	Test summary (JPG)

Tested combinations: 12mm cork floating floor over cork underlayment

Combination	Total tested sound reduction	Source document
12mm floating floor + 3mm cork underlayment	31 dB	Test sheet (JPG)
12mm floating floor + 6mm cork underlayment	42 dB	Test sheet (JPG)
12mm floating floor + 12mm cork underlayment	67 dB	Test sheet (JPG)

The 60-second version for your HOA board

IIC and STC measure the whole building assembly, not a product. Any brand selling “an IIC 72 floor” is selling you the lab’s 10-inch concrete slab.
ΔIIC (ASTM E2179) measures only what the flooring and underlay add. It cannot be inflated by the building. Our 11mm cork floating floor over 6mm cork underlayment tests at ΔIIC +20 — a result most foam underlays don’t approach, whatever their packaging claims.
Every statement in this kit is a document your board can file: test reports per product thickness, on a standard 6-inch concrete reference slab, with and without a suspended ceiling.

Recommended HOA-friendly combinations

Best acoustic result — the board-pleaser. 12mm cork floating flooring over 12mm cork underlayment. Tested at 67 dB total sound reduction; the underlayment alone carries IIC 75 / STC 76 on 6-inch concrete. For wood-frame buildings and the strictest associations.

Best value — the tested assembly. Any 11–12mm cork floating floor over 6mm cork underlayment. This is the exact combination tested to ΔIIC +20 (ASTM E2179) — the number to lead with in the cover letter, because it is building-independent. The 12mm floating version of this pairing tests at 42 dB total reduction.

Slim profile / over radiant heat. Swiss Design 11mm cork floating — 18 dB (EN ISO 717-2), no separate underlayment required thanks to its attached cork underlay layer. Where ceiling height or hydronic heat rules out thick assemblies.

Glue-down route (where the HOA requires bonded floors). 6mm glue-down cork tile at 18 dB impact sound reduction.

Design-led. Swiss TechSlate 7.5mm — stone visuals at approx. 19 dB (EN ISO 717-2), for owners who need approval and a non-cork look.

Download the kit

One zip file with everything your HOA board needs:

12mm / 6mm / 3mm cork underlayment acoustic test statements (PDF)
12mm cork floating floor IIC test reports (PDF)
ΔIIC +20 assembly test summary (JPG)
HOA cover-letter template (PDF + Markdown) — fill in your unit, building, and chosen products
Indoor-air-quality certificates: GreenGuard Gold, ECO Institut, CE (PDF)

Download the Kit (ZIP) Cover Letter Only (PDF) Cover Letter Only (Markdown)

Before you submit

Ask your HOA or property manager one question first: “What is the building’s existing IIC rating?” If the building already tests at 52 and your flooring system adds 20, you are at 72. The cover-letter template in the kit includes this worksheet.

Common HOA questions

My HOA requires IIC 72. Which of your floors meets that?

None on its own — and no competitor’s floor does either, because IIC 72 is an assembly rating, not a product rating. The path to 72 is the building’s existing rating plus your flooring system’s tested contribution. Our 11mm floating floor over 6mm cork underlayment is lab-tested at ΔIIC +20 (ASTM E2179), and the kit gives your board the documents to verify it. Read the full walkthrough in our IIC 72 guide.

My building is wood-frame, not concrete. Does the kit still help?

Yes — wood-joist buildings transmit far more impact sound than concrete slabs, so they benefit the most from a real acoustic layer. Lead with the ΔIIC +20 assembly result (it is building-independent) plus the per-product test statements, and choose one of the thicker combinations above. More detail in why condo floors still have noise complaints.

Will my HOA actually accept these documents?

They are the same third-party lab reports manufacturers submit to architects: per-thickness IIC/STC test statements on a standard 6-inch concrete reference slab, an ASTM E2179 ΔIIC assembly test (NGC report 7013034), and ISO 140-8 / EN ISO 717-2 impact-sound reports for the floors themselves. The cover letter presents them in the format boards are used to seeing.

Can I keep my laminate or LVP and just use your underlayment?

In most cases, yes. Cork underlayment works under almost any floating floor, and many owners use it exactly that way to satisfy an HOA. Pairing it with a cork floating floor adds a second acoustic layer and the highest tested results — see noise reduction and sound control for the per-thickness figures.

Floating Cork Floors

Glue-Down Cork Tiles