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Calcimator

IIC Rating Calculator

Estimate the Impact Insulation Class (IIC) rating of a floor-ceiling assembly based on floor type, underlayment, finish, and ceiling treatment.

Inputs

Results

Estimated IIC rating

32

Base IIC (bare structure)32
Underlayment improvement (pts)0
Floor finish improvement (pts)0
Ceiling improvement (pts)0
Meets IBC code (1=yes, 0=no)0
Points below code18
Quality rating (0-4)0
How to Use This Calculator
  1. Enter Floor structure type, Slab/subfloor thickness (in), and Underlayment type.
  2. Set Underlayment thickness (in), Floor finish, and Ceiling below.
  3. Review the Estimated IIC rating result.
  4. Use Base IIC (bare structure) and Underlayment improvement (pts) to inform your decision.

How the result changes with Slab/subfloor thickness (in)

Slab/subfloor thickness (in)Estimated IIC rating
327
5.531
8.536
1141

What each input means

Floor structure type
1 = Concrete slab, 2 = Wood frame. Concrete provides better base impact isolation.
Slab/subfloor thickness (in)
Thickness of concrete slab or wood subfloor in inches.
Underlayment type
0 = None, 1 = Cork, 2 = Rubber, 3 = Closed-cell foam, 4 = Recycled fiber.
Underlayment thickness (in)
Thickness of the underlayment layer in inches. Common: 1/8", 1/4", 3/8", 1/2".
Floor finish
0 = Bare, 1 = Tile/hardwood, 2 = Laminate, 3 = Engineered wood, 4 = Carpet with pad.
Ceiling below
0 = None/exposed, 1 = Drywall direct-attached, 2 = Drywall on resilient channel, 3 = Suspended acoustical tile.

What each result means

Estimated IIC rating
Estimated Impact Insulation Class rating. IBC code minimum is IIC 50 for multifamily.
Base IIC (bare structure)
IIC rating of the bare floor structure without treatments.
Underlayment improvement (pts)
IIC points gained from the underlayment layer.
Floor finish improvement (pts)
IIC points gained from the floor surface finish.
Ceiling improvement (pts)
IIC points gained from the ceiling treatment below.
Meets IBC code (1=yes, 0=no)
Whether the assembly meets IBC minimum IIC 50 requirement.
Points below code
Number of IIC points needed to reach code minimum (0 if already met).
Quality rating (0-4)
0 = Poor, 1 = Below code, 2 = Meets code, 3 = Good, 4 = Excellent.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Floor structure type = 1, Slab/subfloor thickness (in) = 6, Underlayment type = 0, Underlayment thickness (in) = 0.25 = 6 input(s) provided
  2. Calculate Estimated IIC rating
    Estimated IIC rating
    32 = 32
  3. Calculate Base IIC
    Base IIC
    32 = 32
  4. Calculate Underlayment improvement
    0 = 0

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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