The AV problems that show up on site almost always trace back to a handful of recurring mistakes at design stage: sizing rooms without checking viewing distances, routing containment without allowing for AV cable and rack space, specifying “a screen” instead of defining what the room needs to do, treating AV as an easy value engineering cut, and applying the same spec to rooms with different acoustics and use cases. Each is straightforward to avoid if caught before drawings are fixed, and expensive to fix once they’re not.
Sizing the room without checking viewing distances and sightlines
Room dimensions usually get set by occupancy, furniture layout and circulation space, with the display treated as a fixture to be positioned afterwards. But screen size and viewing distance follow their own rules, and they don’t automatically fit whatever room shape has been agreed. A screen that looks proportionate on an elevation can be too small for anyone at the back of a 12-metre boardroom to read a spreadsheet on, or too large for someone in the front row of a tiered space, forcing an uncomfortable neck angle for an hour at a time.
Sightlines get missed just as often as sizing. Structural columns, exposed ceiling beams and even the AV bracket itself can obstruct part of the room from seeing the display cleanly, and that’s rarely visible on a floor plan — it only shows up when someone models the actual eyelines from every seat. The fix is to check display size against the room’s furthest and nearest viewing distances, and check sightlines against furniture and structural elements, before the room dimensions and display position are locked into the drawings. This belongs in the room-by-room brief at RIBA Stage 2/3, alongside use case — our guide to specifying AV at the right RIBA stages covers how that brief should be built up.
Specifying containment routes without allowing for AV cable counts and rack space
Containment gets drawn to carry power and data, and AV cabling gets assumed to fit into whatever’s left. In practice, a room with a video wall, multiple cameras, ceiling microphones and a control system needs considerably more cable runs than a single data outlet and a socket for a screen, often travelling further, from a rack or comms room rather than a local wall point. When containment is sized for a generic AV allowance rather than the actual equipment count, trays end up full before first fix is finished, and contractors are left improvising surface-mounted trunking on site.
Rack space causes the same problem in a different form. A credenza or rack has to hold amplifiers, switchers, a control processor and network equipment, with rack unit heights, ventilation clearance and cable management all taking up real space — not the gap left in a joinery drawing once everything else has been placed. The fix is a rough containment route and rack elevation produced early enough to check against the architectural and M&E model, not after the ceiling void is carved up. Our post on what to expect from CAD/BIM-aligned AV design sets out what those drawings should contain.
Treating “the room needs a screen” as a sufficient brief
A screen on an elevation isn’t a specification, and the gap between “the room needs a screen” and an actual working brief is where most downstream problems start. A presentation-only room, a video conferencing room and a multi-source room with several switched inputs are three different specifications, not variations on one. Presentation-only needs a display and a source connection, not much else. Video conferencing needs a camera positioned and framed for the seating layout, microphones that cover the table without picking up HVAC noise, and often acoustic treatment the finishes need to accommodate. Multi-source rooms need switching and control on top of that, plus the containment and rack space to carry the extra cabling.
Specifying a screen without settling which of these the room is meant to be leaves the technical requirements to be worked out later — usually by a contractor pricing a tender who has to guess, or by whoever’s using the room after handover discovering the video conferencing they assumed would work simply doesn’t. Getting the use case defined at brief stage, room by room, is the single biggest factor in whether an AV installation does what the client actually needed on day one.
Leaving AV out of value engineering until it’s the easiest line item to cut
AV tends to arrive in a value engineering exercise as a lump sum with no context — a number that’s easy to reduce because nobody in the room can explain what a percentage cut actually removes. That’s usually a symptom of AV being specified generically rather than tied to defined use cases and equipment schedules earlier on. When the AV line is well specified, value engineering can be a genuine trade-off discussion: drop from a video wall to a single large display, or accept a simpler control system, with the client making an informed choice about what they’re giving up.
When it isn’t, cuts get made blind, and the result is a room delivered without the microphone coverage or switching capacity the use case needed — raised as a defect once someone tries to use the room as briefed, with the rework costing more than the original saving. The fix is having AV represented, with a proper specification and cost breakdown behind it, in the same value engineering conversations as every other building service — not brought in afterwards to explain what got lost.
Assuming the same screen and mount works everywhere
A council chamber, a classroom and a boardroom can all be described as “a room with a screen and some seats,” but they behave very differently as AV environments. A council chamber typically needs voting integration, broadcast-quality audio pickup across a large room, and a display or video wall visible from tiered or horseshoe seating with long sightlines. An interactive classroom needs a touch-capable display robust enough for daily use, mounted at a height that works for the age group, in a room with acoustics and ambient light very different from a chamber or boardroom. A boardroom prioritises video conferencing quality and a discreet aesthetic, with acoustic treatment tuned for remote participants rather than a public gallery.
Specifying the same display size, mount and audio approach across all three because they’re all “AV rooms” produces a workable result in none of them. Lighting conditions, ceiling heights, acoustics and the actual task each room is built for all change the spec, and a generic per-room AV allowance set at Stage 1 rarely survives contact with any of them intact.
FAQ
At what stage should these AV specification issues be caught?
Ideally at RIBA Stage 2/3, while room use cases, layouts and containment routes are still flexible. Catching a viewing distance or containment issue on a drawing is far cheaper than catching it once walls are closed up.
Can these mistakes be fixed if a project is already at tender stage?
Some can. A use case that was never properly defined can often still be clarified before tender documents go out, though containment or rack space shortfalls are harder to recover without a revised layout. The later a mistake is caught, the more constrained the fix.
Does every room really need a different AV specification?
Not every room, but rooms with genuinely different acoustics, sightlines or use cases do. Two similar meeting rooms can often share a spec; a council chamber, a classroom and a boardroom cannot.
If you’d rather these decisions were checked against a proper brief than discovered on site, our architects sector page sets out how we work as an AV design partner from concept through to handover, and our design consultation & tender management service covers exactly this kind of early-stage specification work. To talk through a specific project, get in touch.
