· 9 min read
Rw 38 vs Rw 44 vs Rw 50: Acoustic Ratings Explained
What Rw ratings mean for glass partitions, how much privacy Rw 38, Rw 44 and Rw 50 give in practice, and how to choose the right target for each meeting room.
Key takeaways
- Rw is a laboratory measure of how much sound a partition blocks, in decibels.
- Each 10 dB increase is heard as roughly half as loud.
- Installed performance is usually several decibels lower than the lab Rw figure.
- Doors, head tracks and ceiling voids decide real-world privacy as much as the glass.
What is an Rw rating?
Rw stands for weighted sound reduction index. It is a single number, in decibels (dB), that describes how well a building element such as a wall, door or glass partition reduces airborne sound. It is measured in an acoustic laboratory to BS EN ISO 10140 and rated using BS EN ISO 717-1.
The higher the Rw, the more sound the element blocks. A partition rated Rw 44 stops more speech noise than one rated Rw 38. Because decibels are logarithmic, the differences are larger than they look: a 10 dB improvement is perceived by most people as roughly halving the loudness.
When you see Rw quoted for an acoustic glass partition, it refers to the tested system: the specific glass build-up, frame, seals and, sometimes, the door. Change any of those and the rating no longer strictly applies.
Lab Rw vs on-site performance
Laboratory tests isolate the partition from everything around it. On site, sound also travels through door gaps, around head and base tracks, over the top through a shared ceiling void and along continuous floors and walls. This is called flanking.
On-site performance is measured differently, typically as DnT,w, and it is almost always lower than the lab Rw. A difference of several decibels is common even on well-built projects, and it can be far greater where the ceiling void or door has not been treated. That is why we specify a lab rating with headroom above the room’s real-world target.
Rule of thumb: decide the privacy level the room needs, then specify a system Rw a few decibels above it to allow for site conditions.
What Rw 38, Rw 44 and Rw 50 sound like in practice
The table below gives a practical guide to speech privacy for normal conversation through a well-installed partition with a sealed door. Raised voices, presentations and video calls on speaker will carry further, and background noise on the other side of the glass also affects how intelligible speech is.
| Rw rating | Typical system | What you hear outside | Suitable for |
|---|---|---|---|
| Around Rw 32–35 | Standard toughened single glazing | Normal speech is audible and often understood | Open breakout areas, visual separation |
| Around Rw 38 | Acoustic laminated single glazing | Speech audible but mostly not understood | General meeting rooms, team offices |
| Around Rw 44 | High-spec single or entry double glazing | Raised voices faint; normal speech rarely intelligible | Private offices, interview and HR rooms |
| Rw 50 and above | Double glazing with acoustic glass and wide cavity | Speech generally inaudible | Boardrooms, confidential and recording rooms |
Rw 38: the everyday meeting room standard
Rw 38 is a sensible baseline for most general meeting rooms. It is typically achieved with acoustic laminated single glazing in a framed or frameless system. Conversations are audible as a murmur outside the room, but individual words are mostly lost, particularly where there is background noise on the open floor.
It is a good fit for team huddles, internal meetings and project rooms, and it keeps the partition slim and economical. It is not enough for HR discussions or confidential client calls.
Rw 44: private offices and sensitive conversations
Around Rw 44, normal speech becomes hard to follow from outside the room. This is a common target for directors’ offices, interview rooms and rooms used for one-to-ones. It can be achieved with high-performance single glazing in some systems, but more often with a double-glazed system.
At this level the door becomes critical. A framed door with full perimeter seals and an automatic drop-down threshold seal is usually needed, and the ceiling void above the partition should be closed with an acoustic barrier.
Rw 50 and above: boardrooms and confidential rooms
Rw 50 and above is the territory of boardrooms, legal and financial meeting rooms, and spaces used for recording or broadcasting. It requires double glazing, usually with acoustic laminated glass on one or both sides and a deeper cavity, plus a fully sealed door set and careful treatment of every junction.
Specifying this level only makes sense if the surrounding construction can support it. There is little value in an Rw 50 partition if the adjoining plasterboard wall or the ceiling tiles above it perform far worse.
Where acoustic performance is lost
In our experience, disappointing acoustics are almost never caused by the glass alone. These are the usual weak points:
- Door gaps — an unsealed threshold can undo most of the partition’s performance
- Ceiling voids — sound passes over the partition through a shared void above suspended ceilings
- Head and base tracks — gaps against uneven slabs or ceilings need acoustic sealing
- Junctions with walls and mullions — especially where the partition meets a window
- Services — ductwork, trunking and raised floors that run beneath or over the partition
How to choose the right Rw for each room
Start with how the room will be used, not with a number. List each room type on your plan, decide how private conversations need to be, then set a target for each. It is often more cost-effective to put a higher-performance system on the two or three rooms that need it and a lighter system everywhere else.
For a practical walkthrough of planning rooms on an office floor, see our office glass partitions guide. If you are weighing relocatable systems, the acoustic implications are covered in demountable vs fixed glass partitions.
- Breakout and visual separation: no specific target
- General meeting rooms: around Rw 38
- Private offices and one-to-one rooms: around Rw 44
- Boardrooms and confidential rooms: Rw 50 and above
Questions
Is Rw the same as dB reduction on site?
Not exactly. Rw is a laboratory rating. On-site performance is measured as DnT,w and is usually lower because of flanking paths such as doors and ceiling voids.
Can single glazing reach Rw 44?
Some high-performance single-glazed systems with thick acoustic laminated glass approach this level, but double glazing is the more reliable route, especially once door performance is taken into account.
Does a glass door reduce the acoustic rating?
The door is usually the weakest element. Framed doors with perimeter seals and drop-down threshold seals perform far better than frameless doors with open gaps.
Do you provide acoustic test data?
We specify systems with manufacturer test data for the exact build-up being installed, and can share the relevant certificates during the specification stage.
