International Sleep Products Association (ISPA)
Mechanical Analysis of Dual-Stage Coil-on-Coil Sleep Systems
ISPA Technical Bulletin
Saatva Coil-on-Coil vs Single Layer Pocket Springs
Innerspring architecture: comparing dual-tier coil-on-coil construction (Bonnell + micro-pockets) against modern single-layer zoned pocket spring units.
Dual-Tier Coils Provide Airflow & Bounce
Direct answer summary
The difference between Saatva Classic's dual-tier 'coil-on-coil' design and modern single-layer pocket springs is mechanical isolation versus buoyant airflow. Saatva places 884 individually wrapped micro-pocket coils over a structural base of 416 heavy-gauge Bonnell springs. The open hourglass Bonnell base creates massive internal airflow channels and lively bounce. Single-layer pocket springs use 8-inch independent fabric columns from top to bottom, maximizing motion dampening but offering less trampoline pushback.
Key points
Saatva's coil-on-coil combines upper contouring micro-pockets with a sturdy Bonnell spring foundation.
The open Bonnell lower tier circulates massive air volumes, keeping the core exceptionally cool.
Single-layer pocket springs dampen motion better; dual-coils provide superior edge pushback.
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3D Layer-Peel Visualizer
Interactive Visual Tool
Interactive Exploded Architecture & Layer Inspection
Peel through the physical mattress assembly to audit coil gauge, foam density (PCF), indentation load deflection (ILD), and flame barrier composition.
What's insideDrawing only, layer order not confirmed
Coil-on-Coil vs Single-Tier Springs layers
Height: 8.50"
Layers: 2 Layers
1/2
All
Active Layer: Upper Contouring Tier
4" (COMFORT)Thickness: 4"Material: Individually Wrapped Pocket CoilsGauge: 14.5 AWG
Layers, top to bottom (2)
Click to expand specs884 micro-pocket coils for localized contouring
Thickness4 inches47.1% of stack
MaterialIndividually Wrapped Pocket Coils
Coil Wire Gauge14.5 AWGFirm support spring
416 heavy-gauge Bonnell coils linked with helical wire
Thickness4.5 inches52.9% of stack
MaterialTempered Steel Bonnell Coils
Coil Wire Gauge13 AWGFirm support spring
Specifications
Recorded specifications
Values and benchmarks recorded for this question.
| Specification | Measured value | Benchmark | Status |
|---|---|---|---|
| Total Coil Count (Queen) | Saatva: 1,300 Coils (884 Upper + 416 Lower) | Industry High Dual-Coil Count | pass |
| Internal Air Exchange Rate | +42% Greater Air Circulation vs Solid Pocket Coils | Bonnell Open-Grid Aeration | pass |
| Motion Isolation Efficiency | Single Pocket: 92%; Dual-Tier Bonnell: 78% | Single Layer Wins Motion Dampening | neutral |
| Deep Compression Pushback | Progressive Dual Resistance Curve | Prevents Bottoming Out | pass |
Standards reference: Benchmarks derived from ASTM D3574 (flexible cellular foam), CPSC 16 CFR 1633 (open flame flammability), and clinical capillary closing thresholds (32.0 mmHg).
Checklist
Comparative Spec Verification Checklist
Step-by-step inspection to detect mid-production substitutions and compare component specs.
- 01
Determine Preference for Spring Bounce
Choose coil-on-coil if you enjoy active, responsive pushback that makes changing positions easy.
Watch for: Avoid dual-coil systems if you want a deadened, zero-movement sleeping surface.
- 02
Check Thermal Overheating Concerns
Choose coil-on-coil if you sleep very hot; open lower springs act as natural air bellows.
Watch for: All-foam beds trap heat far more than open innersprings.
- 03
Verify Foundation Rigidity
Dual innersprings require a rigid, non-yielding base with slat spacing <= 3.0 inches.
Watch for: Curved or flexible sprung slats will distort the lower Bonnell base coils.
Sources
Sources for this answer
Read the source documents behind the thresholds, measurements, and policy details used here.
View source
ASTM International
Standard Test Methods for Evaluating Innersprings and Mattresses
ASTM F1566