A condo rule that quotes an "IIC" number is pointing at one of three different measurements, and the rule rarely says which one. This page covers IIC vs STC condo flooring in plain terms: what a laboratory IIC, a field result and an airborne STC each describe, what the Ontario Building Code asks for between suites, and what the IIC 73 / STC 72 wording on our SPC vinyl plank pages can and cannot show.
The short version: the code asks for airborne sound control between dwelling units, and the explanatory note to its sound section says there are no impact-noise requirements there. Any impact figure therefore comes from your condo corporation's own documents. The sound line on a product page is that page's statement, not a measurement of your slab and your neighbour's ceiling. If you are still choosing a floor, our vinyl flooring collection lists the planks discussed below.
Three measurements that all get called "the IIC number"
A single figure in a rule can belong to any of the tests below. The table pairs each name with its setting and its ASTM method, and the paragraphs after it use ASTM's own wording. Plain-language entries for the same terms sit in our flooring glossary.
| Name | Setting | Method |
|---|---|---|
| IIC (impact insulation class) | Laboratory | ASTM E492 |
| FIIC (field impact insulation class) | Field, older name | ASTM E1007 |
| AIIC, ISR, NISR | Field, current names | ASTM E1007 |
| STC (sound transmission class) | Laboratory, airborne | ASTM E90 |
| ASTC (apparent sound transmission class) | Field, airborne | ASTM E336 |
ASTM E492 is the laboratory method. It covers the laboratory measurement of impact sound transmission of floor-ceiling assemblies using a standardized tapping machine, and the single-number rating tied to it is the impact insulation class (IIC).
Field results come from ASTM E1007, which covers impact sound generated by a standard tapping machine through floor-ceiling assemblies and associated supporting structures in field situations. FIIC is the older name for that field rating. An earlier edition of ASTM's classification document says the single-number rating is called field impact insulation class (FIIC) for E1007, while the current edition lists apparent impact insulation class (AIIC), impact sound rating (ISR) and normalized impact sound rating (NISR) instead.
Airborne sound has its own pair. The Ontario Building Code says STC ratings of separating assemblies are determined using results from measurements carried out in accordance with ASTM E90, a laboratory method. ASTC comes from ASTM E336, titled as a measurement of Airborne Sound Attenuation between Rooms in Buildings, or from the code's calculation methods. ASTM adds that its NIC, NNIC and ASTC ratings are distinct metrics that describe acoustical performance differently, so they cannot be swapped for one another.
Why a lab figure and a field figure are different numbers
ASTM E492 spells out the gap itself. It says the method is not intended for field tests, and that sound ratings obtained with it do not relate directly to sound isolation in buildings. It describes them as an upper limit to what would be measured in a field test.
The field method carries its own caution. ASTM E1007 says a single field measurement only represents the performance of the actual assembly tested. Its AIIC metrics are meant to evaluate the floor-ceiling assembly and adjacent structures as installed, so structure-borne flanking paths are part of the result.
For a reader holding a rule, that comes to three practical points. A lab IIC and a field result are separate quantities. Neither belongs to a plank on its own, because both describe an assembly. And a result measured in one building does not carry over to another by default.
What the Ontario Building Code requires between suites
Division B, Article 9.11.1.1 of the 2024 Ontario Building Code (Part 9) says a dwelling unit must be separated from every other space in a building in which noise may be generated by a separating assembly and adjoining constructions that together provide an apparent sound transmission class (ASTC) rating of not less than 47, or by a separating assembly with an STC of at least 50 and adjoining constructions that conform to Article 9.11.1.4. Part 5 of the same code sets the same two routes in Article 5.8.1.1: an ASTC rating not less than 47, or a separating assembly with an STC rating of not less than 50. The National Building Code of Canada 2020 sets the same two routes in Article 5.8.1.1: an ASTC rating not less than 47, or a separating assembly with an STC rating of not less than 50.
Both routes are airborne. The article names ASTC and STC and no impact rating, and the explanatory note to Section 9.11 says so directly: it has no requirements for control of impact noise transmission. The NBC 2020 note says the same and adds that impact noise requirements are being considered for inclusion in future editions of the NBC.
The same note does name a benchmark, described as a recommended criterion: bare floors tested without a carpet should achieve an impact insulation class (IIC) of 55. A recommendation in explanatory material is not a requirement for any particular building, and the Compendium preface describes its Appendix Notes as prepared for purposes of convenience only. Ontario's Supplementary Standard SB-3 also carries sound-resistance tables, and says they are provided only for the convenience of Code users.
Which edition applies to a given tower depends on when it was permitted. Ontario says the 2024 Building Code comes into effect on January 1, 2025, with a three-month grace period until March 31, 2025, and that applications until December 31, 2024 must be submitted using the 2012 Building Code. We quote the 2024 text and do not say which edition governs your building.
Who sets the number in your building
Every condo corporation has its own declaration, by-laws and rules, according to the Condominium Authority of Ontario. Its noise guidance adds that each corporation has unique provisions dealing with noise in its governing documents, and that what is allowed varies from community to community. So the number in your rules comes from your corporation, not from the code, and it can name any of the measurements above.
The same guidance says the Condo Act prohibits unreasonable noise in units or common elements regardless of what a corporation's documents say. That duty sits alongside your corporation's own rules, so a number met on paper is only one part of the noise question. For the board-rules side, our condo flooring guide is the place to start. Two other posts cover condo board rules and sound ratings and STC and IIC in simple terms, so this page does not repeat them.
For rules that limit hard flooring or require bedroom carpet, see our guide to condo by-law hard flooring limits.
To see what a board may ask you to file, read our guide to condo board approval for flooring.
What the IIC 73 / STC 72 line on a plank page can and cannot show
Of the 87 SPC vinyl planks that are active and in stock in our catalogue, the product pages of 80 state IIC 73 and STC 72. The other seven pages do not state it. Within the 80, the same two numbers sit on planks of five different total thicknesses, with a pad attached to each plank according to its page.
| Total thickness on the page | Planks stating IIC 73 / STC 72 | Pad stated on the page |
|---|---|---|
| 6mm | 9 | 1.5mm IXPE |
| 6.5mm | 10 | 1.5mm IXPE |
| 8mm | 19 | 2mm EVA |
| 9mm | 18 | 2mm EVA |
| 10mm | 24 | 2mm EVA |
ASTM's impact-sound methods above describe floor-ceiling assemblies. None of those 80 pages names a test standard, a laboratory, a slab or a ceiling. The pages therefore tell you what the listing states, and nothing about how the figure was measured. Treat the line as a question to put to the supplier, not as proof for your building.
Five pad-attached planks and their prices
| Plank | Thickness | Pad on the page | Box price | Sq ft per box | Price per sq ft |
|---|---|---|---|---|---|
| Riche Blonde Sand Oak SPC vinyl plank | 6mm | 1.5mm IXPE | $44.68 | 23.64 sq ft | $1.89 |
| Riche Heavy-Duty Nordic Frost SPC vinyl plank | 8mm | 2mm EVA | $37.24 | 16.55 sq ft | $2.25 |
| Riche Ivory Linen SPC vinyl plank | 9mm | 2mm EVA | $32.96 | 13.79 sq ft | $2.39 |
| Riche Cloud White Oak SPC vinyl plank | 9mm | 2mm EVA | $35.31 | 14.18 sq ft | $2.49 |
| Riche Ultra-Thick Tobacco Oak SPC vinyl plank | 10mm | 2mm EVA | $39.60 | 11.82 sq ft | $3.35 |
Prices checked October 31, 2026. Box prices and coverage come from our current catalogue, and the price per sq ft is the box price divided by the coverage per box, rounded to the cent.
The 6mm Blonde Sand Oak plank is the thinnest of the five. Its page describes a 4.5mm SPC core with a factory-attached 1.5mm IXPE underpad and gives the sound rating as IIC 73 / STC 72. At $1.89 per sq ft it is priced below the other four.
Ivory Linen is a 9mm plank. The page lists a 7mm SPC core and a pre-attached 2mm EVA underpad, and states the same IIC 73 / STC 72. A thicker core and a thicker pad do not change the numbers on the page, which is one reason to hold the label loosely.
On the 8mm Nordic Frost page, the acoustics line reads "IIC 73 / STC 72 (Condo Approved)". Wording like that describes how a listing is pitched. Whether a floor is acceptable in your building is decided under your corporation's own documents, not by a phrase on a product page.
The 10mm Tobacco Oak page pairs an 8mm SPC core with a 2mm EVA pad and states the same two numbers as the 6mm Blonde Sand Oak. The price per sq ft is $1.46 higher, and the sound line has not moved. A higher price on these pages does not buy a different number on the label.
The same two numbers on a loose underlay roll
Our UHD Black underlayment carries IIC 73 STC 72 in its title and is sold as a 100 sq ft roll for $50.00, which works out to $0.50 per sq ft. Its page has a line reading Sound ratings: IIC 73, STC 72, and names no plank, slab or ceiling. A roll with no plank on it and planks with a pad bonded on state an identical pair, so the pair cannot be a result for one specific stack in your suite.
None of this makes the lines wrong. A repeated number is a listing statement until a document names how it was measured. Whether a plank also needs a separate layer is a different question, covered in our post on underlayment for SPC vinyl, and the footfall tone you hear inside your own unit is covered in why SPC can sound hollow.
Three questions to put to the building before you order
- Which measurement does the rule name? If it says only "IIC", ask whether it means a lab report, a field result in the finished suite, or an airborne STC or ASTC figure. Ask for the wording in writing.
- Is the number for a floor-ceiling assembly? If the rule assumes a particular slab and ceiling, ask which, because the standards above describe whole assemblies and not a plank on its own.
- Will a product page statement do? If the rule needs a measured result, ask the supplier whether a report exists for the exact plank and pad, and which standard, slab and ceiling it names. The pages we checked do not name them.
FAQ: FIIC, IIC, STC and attached pads
What is FIIC, and is it the same as IIC?
No. FIIC is the older name for a field result under ASTM E1007, while IIC is the laboratory rating tied to ASTM E492. Current ASTM wording for field results is AIIC, ISR or NISR, so a rule that says FIIC is pointing to a field measurement.
Is IIC required by the Ontario Building Code?
The code's between-suites requirement is airborne, stated as ASTC 47 or an STC of 50 with conforming construction. The explanatory note says Section 9.11 has no impact-noise requirements, so an IIC figure in a condo rule comes from the corporation's declaration, by-laws or rules.
Does an SPC plank with the pad attached meet a condo's sound rule?
Not on the strength of a product page alone. The pages state IIC 73 and STC 72 but do not name a test standard, slab or ceiling, and your corporation's documents decide what it accepts. Ask the building what it needs, then ask the supplier what documents exist.
Why do planks of different thickness state the same IIC and STC?
The pages do not explain it. Across the 80 planks, thickness runs from 6mm to 10mm while the stated pair stays the same, and none of the pages names how the pair was measured. That is a reason to ask for the underlying document rather than to compare the numbers.
Get an SPC vinyl plank quote in Toronto and the GTA
If you have your building's wording in hand and want the planks above priced for your suite, send us the details through our quote request page.
Top Floorings Depot
3781 Victoria Park Avenue, Unit 1, Toronto, ON M1W 3K5
www.topfloorings.com
Call: 416-499-0117
Text: 416-770-8819