BB93 Explained: UK School Acoustic Requirements
If you've been sent a report that just says "the school meets BB93," ask which room it's talking about. There isn't a single BB93 target. There are more than a dozen, and mixing them up is one of the most common mistakes we see in school acoustic specifications, sometimes written by people who should know better.
I'm going to walk through the standard the way we actually use it on site: what each number means, why the targets differ so much between a primary classroom and a sports hall, and what it takes to demonstrate compliance in a way that survives scrutiny from building control.
What BB93 actually is
Building Bulletin 93, Acoustic Design of Schools: Performance Standards, is the Department for Education's technical standard for school acoustics in England. The current edition was published in February 2015 and replaced the 2003 version entirely, tightening several targets along the way. It sits underneath Building Regulations Part E for new-build and substantially refurbished school buildings, which is why building control will ask for evidence against it, not just a design intention.
The standard covers three things: how much noise gets into a teaching space from outside (road traffic, other classrooms, building services), how much reverberation the room itself has, and, for some spaces, sound insulation between rooms. Most conversations focus on reverberation time, because it's the one that's cheapest to get wrong and most obvious once pupils are actually using the room.
The full reverberation time table
Reverberation time, RT60, is measured in seconds and represents how long it takes sound to decay by 60 decibels after the source stops, tested to ISO 3382-2 in a furnished but unoccupied room. BB93 sets a different RT60 ceiling for each room type, because a primary classroom, a sports hall and a music room do fundamentally different jobs acoustically.
| Room type | Maximum RT60 | Maximum background noise |
|---|---|---|
| Primary classroom | 0.6 seconds | 35 dB LAeq,30min |
| Secondary classroom | 0.8 seconds | 40 dB LAeq,30min |
| SEN resource base | 0.4 seconds | 30 dB LAeq,30min |
| Hearing-impaired classroom | 0.4 seconds | 30 dB LAeq,30min |
| Music room | 0.6 to 1.0 seconds | 35 dB LAeq,30min |
| Drama studio | 0.6 to 1.0 seconds | 35 dB LAeq,30min |
| Assembly hall | 0.8 seconds | 35 dB LAeq,30min |
| Dining hall | 1.0 seconds | 45 dB LAeq,30min |
| Sports hall | 1.5 seconds | 45 dB LAeq,30min |
| Corridor | 1.5 seconds | 45 dB LAeq,30min |
A few things worth pulling out of that table. Primary classrooms are held to a tighter target than secondary ones (0.6 seconds against 0.8), because younger children have less vocabulary and linguistic context to fall back on when they miss a word to reverberation. A five-year-old can't infer a mispronounced or masked syllable the way a sixteen-year-old can, so the room has to do more of the work.
SEN and hearing-impaired spaces sit at 0.4 seconds, the tightest figure in the whole standard, and for good reason. Pupils relying on residual hearing or lip-reading need speech to arrive clean, without the smearing that reverberation adds to consonant sounds specifically, which is where most of the intelligibility in speech actually lives.
Why the classroom-only approach fails
Look at that table again and notice how much of a typical school day happens outside a classroom. Dining halls, corridors, assembly spaces and sports halls all carry their own targets, and all of them are frequently untreated because the original brief only asked for "the classrooms."
A corridor rated to 1.5 seconds sounds generous next to a classroom's 0.6, until you remember that corridors connect directly to classrooms. Untreated circulation space bleeds noise into the rooms either side of it, quietly working against whatever you've just spent the budget achieving in the teaching spaces. We treat corridors as part of the same project for exactly this reason, not as an afterthought.
How compliance is actually demonstrated
A specification that looks right on paper isn't the same as a compliant room. Post-installation testing, measuring the room's actual RT60 against its BB93 target with calibrated equipment, is what produces the written compliance record building control will want to see. Where testing is added as an option, each room is tested against its specific target from that table, not a generic figure, and the results are issued in writing with the completion sign-off.
Common questions
Does BB93 apply to existing schools, or only new builds? It's a Building Regulations requirement for new-build and significantly refurbished school buildings. Many existing schools treat acoustics voluntarily outside of a regulated project, and we'd encourage it, poor acoustics don't wait for a refurbishment programme to start affecting attainment.
Who actually checks BB93 compliance? Building control sign off the project, but the acoustic evidence itself comes from an independent test against the room's specific RT60 target, carried out after installation.
Does the standard cover sound insulation between classrooms too? Yes, BB93 also sets airborne and impact sound insulation values between teaching spaces, alongside the reverberation and background noise targets covered here.
Getting your school assessed against the right targets
See our guide to school-wide BB93 compliance, or book a free acoustic survey and we'll tell you exactly which target applies to each room on your site, not a single number for the whole school.
Related product guides: acoustic ceiling tiles, PET acoustic panels.
From first survey to final finish
One team handles all seven stages, the same way on every project, so you always know what happens next.
A surveyor visits the site, or works from your drawings and photos when a visit isn't practical. Either way, the room, its surfaces and how it is used are recorded before any advice is given.
Reverberation, ambient noise and noise transfer are read against what the space is used for. The findings arrive as a written report with recommendations, yours to keep with no obligation to proceed.
Treatment is modelled against a reverberation target, then drawn up with panel positions, fixings and finishes. Nothing moves forward until you have approved the design.
Every quotation comes with the specification behind it, listing products by type, quantity and finish with costs set out line by line. What is quoted is what the design calls for.
Panels, baffles, ceilings and screens come from our Acoustic Solutions range and are supplied to the approved specification. What arrives on site matches what was designed.
Our own engineers fit to the approved drawings, checking positions and fixings as they go. One team supplies and installs, so nothing is handed between contractors.
Optional: after fit-out the space can be measured again and compared with the original survey, so the improvement is measured rather than assumed. Results are reported against the relevant standards and the written record goes into your building file.
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