Closing the door does not make a conversation private. In most modern Thai office fit-outs — where walls are lightweight metal stud and single gypsum board, designed to be fast and cost-effective to build — speech travels between spaces with minimal attenuation. The person at the hot-desk outside your HR room may not be listening. But they can hear everything anyway.

This is not a minor inconvenience. In regulated industries — financial services, legal, healthcare, government — inadequate acoustic privacy in meeting rooms is a compliance and governance risk. In any business handling sensitive HR matters, confidential negotiations, or commercially sensitive strategy discussions, it's a reputational and legal exposure.

Understanding STC: The Only Number That Matters for Meeting Room Walls

STC (Sound Transmission Class) is the standard measure of how much a wall, floor, or ceiling attenuates airborne sound. It represents the decibels of sound reduction across the structure. The higher the number, the more private the room. Here's what different STC ratings mean in practice:

Why Most Bangkok Office Meeting Rooms Underperform

The typical Thai commercial office fit-out uses 75mm or 100mm metal stud framing with single 12mm gypsum board on each face. This construction achieves approximately STC 38–42 — enough to muffle sound but not nearly enough to prevent intelligibility. The reasons this has become standard are familiar: it's fast to install, inexpensive, and compliant with fire codes. Acoustic performance is rarely part of the fit-out brief.

The problem is compounded by two common failure points that almost every office has:

1. Doors. A STC 50 wall with a standard hollow-core door is effectively a STC 30 room. The door is the weakest link — and in most offices, it's dramatically weaker than the walls it's set into.

2. Flanking paths. Sound doesn't only travel through walls. It also travels over the top of a partition (through a shared suspended ceiling space), under doors (through the gap), and through shared ductwork. A room that has been perfectly treated acoustically can still have poor privacy because of a duct connection to the adjacent space.

What a Proper Speech-Private Meeting Room Requires

The Door Problem: Your Wall Is Only as Good as Its Weakest Point

This is the most commonly overlooked element in office acoustic upgrades. A correctly specified meeting room wall assembly can achieve STC 52. A standard flush panel door in that same wall performs at STC 20–28. The combined effect is a room that performs far below specification.

IAC Acoustics Thailand supplies acoustic doors from STC 43 to STC 64 — designed to match or exceed the performance of the surrounding wall assembly. Unlike standard commercial doors, acoustic doors feature heavy-duty seals on all four sides (including automatic drop seals at the bottom), solid-core or composite construction, and tested, certified ratings rather than estimated performance.

"We'd spent a reasonable budget on the partition walls for our new boardroom. Then we put in a standard fire door because it was quicker to source. The result was that every meeting was audible in the reception area. The acoustic door replacement was expensive and disruptive. We should have specified it correctly from the start."

— Office Manager, professional services firm, Bangkok

Comparison: Common Meeting Room Wall Specifications

Retrofitting vs. New Build: What's Possible

The best time to specify acoustic meeting rooms is during the initial fit-out. But many Thai office buildings are retrofitting existing spaces — and there's still significant improvement available even within the constraints of an occupied building.

The most practical retrofit path is to add a new layer to existing partitions: a resilient channel layer with a gypsum board facing, with BB830 MLV installed against the existing wall and acoustic sealant at all perimeters. This doesn't require demolishing the existing partition, adds approximately 60–80mm to each treated wall face, and can typically be installed outside working hours with minimal disruption.

Combined with an acoustic door replacement, this retrofit approach can bring a marginal meeting room to full speech-private specification in most cases.