Neither mass loaded vinyl nor fiberglass is universally better — they do different jobs, and the Soundsulate LAG composite works precisely because it combines both. Mass loaded vinyl blocks airborne sound transmission; fiberglass absorbs and decouples vibration. Choosing one over the other without knowing your noise type is the wrong starting point.
Mass loaded vinyl adds mass to a barrier, which is what stops airborne sound — voices, traffic, machinery hum — from passing through a wall, floor, or pipe wrap. Fiberglass doesn't block; it absorbs mid-to-high frequency energy and breaks the rigid connection between a vibrating surface and the barrier layer. In the Soundsulate LAG composite, the quilted fiberglass decoupler addresses the structural vibration that bare mass loaded vinyl can't stop on its own, which is why the LAG assembly reaches STC 29 while 1 lb mass loaded vinyl alone rates STC 27.
- Soundsulate 1 lb mass loaded vinyl STC rating: 27 as a standalone material.
- Soundsulate LAG composite (1/8" foil-faced MLV laminated to quilted fiberglass): STC up to 29.
- Mass loaded vinyl weight options: 1/2 lb, 1 lb, 1.5 lb, and 2 lb per square foot.
- Quilted fiberglass layer in the LAG product: 2" thick, providing absorption and vibration decoupling.
- Mass loaded vinyl function: blocks airborne noise; fiberglass function: absorbs sound energy and isolates structure-borne vibration.
Side-by-Side Comparison
| Dimension | Soundsulate 1 lb Mass Loaded Vinyl | Quilted Fiberglass Decoupler | Soundsulate LAG Composite |
|---|---|---|---|
| Primary mechanism | Adds mass to block airborne sound transmission | Absorbs mid-to-high frequency energy; breaks vibration path | Mass blocking plus absorption and decoupling in one layer |
| STC rating | STC 27 as standalone material | No STC rating — absorption, not blocking | STC up to 29 as pipe/duct wrap assembly |
| Impact / structure-borne noise | Not effective — mass alone doesn't stop vibration transfer | Effective — fiberglass isolates structure-borne vibration | Effective — fiberglass layer handles what the MLV layer can't |
| Best application | Wall, floor, and ceiling barriers where airborne noise is the problem | Pipe wraps, duct enclosures, machinery where vibration isolation is needed | Pipe and duct wraps requiring both airborne blocking and vibration isolation |
| Thickness | 1/8" at 1 lb per square foot | 2" quilted fiberglass layer | Combined assembly — MLV face plus 2" fiberglass backer |
How to Choose
- Pick Soundsulate 1 lb mass loaded vinyl if: your problem is airborne noise — voices, traffic, or machinery hum — traveling through a wall or floor where you need added mass without bulk.
- Pick Soundsulate 2 lb mass loaded vinyl if: the airborne noise has significant low-frequency content, such as HVAC equipment or subwoofer bleed, and the structure can support the added weight.
- Pick the Soundsulate LAG composite if: you're wrapping pipes or ducts where structural vibration is part of the problem — bare mass loaded vinyl alone won't stop vibration transferring through contact.
- Pick fiberglass absorption (not mass loaded vinyl) if: your issue is echo and reverb inside a room, not sound transmitting through the structure — mass adds nothing to in-room acoustics.
- Pick the Soundsulate LAG composite over bare mass loaded vinyl if: you need both blocking and decoupling in a single wrap assembly and the STC gain from 27 to 29 matters for your spec.