PAC International IFB1
The PAC International IFB1 is a resilient rubber Isolation Floor Block designed to break the vibration path between a finished floor layer and the structural deck below. Installed at a project-specific grid under sleepers or subfloor sheathing, it delivers a consistent acoustic break for high-IIC floor assemblies without the height buildup of full floating-floor systems.
- True Floor Decoupling: Places a resilient rubber isolator between subfloor and structure so footfall and airborne energy don't pass rigidly into the deck.
- Standard-Density Isolator: Tuned for typical residential and light-commercial floor loads — pair with IFB2 where higher point loads or heavier finish floors are present.
- Low-Profile Buildup: Fraction of the height of a floating slab or full floating-floor cassette while still delivering a measurable IIC lift.
- Grid-Layout Friendly: Set at a project-engineered spacing to distribute floor load evenly across isolators — no continuous mat required.
Online orders up to 4,999 pieces. For anything larger, call (415) 864-4440 and we'll price the project with you.
Volume pricing
$6.99 per isolator. Order 250+ isolators and pay $6.79 per isolator — an extra $0.20 off per isolator for each additional 250 isolators, down to a $5.50 per isolator floor.
Discounts apply automatically in the cart and count boxes and cases toward the total.
IFB1 Specifications
- Application
- Floor decoupling — under sleepers or subfloor sheathing
- Footprint
- 2 in. × 2 in.
- Height
- 1 in.
- Density options
- SD170 (80 lbs), SD260 (116 lbs), SD400 (172 lbs), SD650 (240 lbs) — rated load per block
- Isolation element
- Molded rubber pad (standard density)
- Layout
- Project-engineered grid — consult acoustic engineer
- Mounting
- Loose-lay under sleepers / subfloor — no fasteners through isolator
- Compatible finishes
- Wood, LVT, tile-over-subfloor, floating floor
Rockwool Safe'N'Sound R11
- R-Value
- R-11
- Material
- Stone wool (basalt rock + recycled slag)
- Framing fit
- 2×4 stud and joist cavities, 16" or 24" o.c.
- Density
- Higher than standard fiberglass batt
- Fire performance
- Non-combustible, melting point ~2,150°F
- Water repellency
- Water-repellent, won’t support mold growth
- Install method
- Friction-fit; cut with a long serrated knife
- Coverage
- Approx. 60 sq ft per bag
IFB1 Project Calculator
Enter your surface square footage. We'll return a clip, channel, and screw count for your project — calculations run on our servers so estimates stay accurate as our field data improves.
- Rockwool insulation
- Direct-mount clips
- Mass-loaded vinyl (MLV)
- Acoustic sealant
Adds MLV over Good for a denser limp-mass layer.
Layout is project-engineered based on floor load and finish. Consult an acoustic engineer, then add a 10% coverage buffer for cuts and re-work.
IIC Gauge
Compare how the IFB1 performs across assembly tiers. Select an assembly below to see the resulting IIC score.
IFB1 grid + Rockwool + MLV + double subfloor with Green Glue between layers.
- STC 30-39: Loud speech clearly audible next room.
- STC 40-49: Loud speech muffled — normal residential wall.
- STC 50-59: Loud speech barely audible; suitable for offices & multi-family.
- STC 60+: Approaches studio-grade isolation.
How IFB1 compares
| Model | Primary Use | Density | Typical Layout | Isolation Element |
|---|---|---|---|---|
| IFB1this | Floor decoupling under sleepers / subfloor | Standard | Project-engineered grid | Molded rubber pad |
| IFB2 | Floor decoupling — higher load / heavier finish | High-density | Project-engineered grid | Molded rubber pad (denser elastomer) |
Applicable Assemblies
See where the IFB1 fits — from budget baseline to studio-grade isolation.
Best — IFB1 + Rockwool + MLV + Double Subfloor + Green Glue
Structural deck · IFB1 isolation blocks on engineered grid · Rockwool cavity · MLV underlay · double subfloor with Green Glue between layers · finished floor · perimeter acoustic sealant.
Better — IFB1 + Sleepers + Double Subfloor + Green Glue
Structural deck · IFB1 isolation blocks · sleepers · double subfloor with Green Glue between layers · finished floor · perimeter acoustic sealant.
Good — IFB1 + Sleepers + Subfloor
Structural deck · IFB1 isolation blocks on engineered grid · sleepers · single subfloor · finished floor · perimeter acoustic sealant.
