Environment and mounting first
Start with where the wall lives. Indoor, semi-outdoor and outdoor classes call for different sealing, cooling and brightness, and the mounting type decides service access and structural load.
Record the surface, the available depth behind it, and any weight or wind limit. A recessed indoor feature and a freestanding outdoor structure are different orders even when the screen size looks the same.
Lock the environment class before discussing image numbers, because nearly every other parameter depends on it.
Image performance you can verify
Pitch should follow from the closest viewing distance and the most detailed content, not from a default. State the distance and the content so the pitch is justified, not assumed.
Brightness belongs with the light level it must beat. Give the ambient condition and ask for a figure that holds up there, not a generic maximum that only appears in a dark room.
Note colour, uniformity and refresh behaviour if the wall will be filmed, because camera performance is a separate requirement from eye-level comfort and is easy to overlook.
Service and access constraints
State which service direction the site permits. A flush wall with no rear access needs front-serviceable cabinets; a wall with a service room can use rear service and stay slimmer.
List the spare parts to keep on site and how a faulty module is identified and replaced. A wall that cannot be serviced on a schedule will drift in appearance over time.
Confirm who services it. If a contractor other than the installer will maintain the wall, the specification must be readable by that person without tribal knowledge.
Control, content and power
Define the control system and the content workflow, including who updates content and from where. A wall is only as useful as the path that puts an image on it.
Specify power, data routing and isolation per section so a fault does not take the whole wall dark. Local isolation also makes repairs faster and safer.
Call out any integration with building systems, sensors or scheduling, because those links are where projects slip if they are left to the install week.
Acceptance before you sign off
Write the acceptance criteria you will actually check: brightness at the site light level, dead-pixel and uniformity limits, colour consistency across cabinets, and a clean boot with no flicker.
Agree how deviation is measured and what counts as a pass, so delivery is a test, not an opinion. Keep the measured results against the spec for warranty and future service.
Treat the signed acceptance as the close of the specification loop. A brief that was checked this way is far less likely to surface a costly surprise after install.
A spec that skipped the environment
An order fixed pitch and brightness but not the environment class. The chosen panels lacked the right enclosure for the site, forcing a late swap.
Acceptance left to chance
A wall was accepted on a glance because the spec had no tests. Later a colour issue was disputed; written acceptance criteria would have settled it at handover.
Steps for a project: specification checklist before buying
- Start with environment and mounting Fix the environment class, indoor or outdoor, and the mount type before anything else. These constrain every later choice, from enclosure to service direction.
- Set pitch from the closest viewer and content Derive pitch from the nearest viewing distance and what you show. A specification that picks pitch before the viewer often pays for sharpness nobody needs or lacks it where it matters.
- Specify brightness for the real light Set brightness against the actual ambient, not a catalogue number. A dim room needs far less than a sunlit window.
- Write acceptance before you sign Define the acceptance tests and limits in the spec so sign-off is objective. Without them, 'good enough' becomes a negotiation.
Assumptions to check on specification checklist before buying
“Brightness should be specified as a maximum.” — Brightness is a minimum for the site's light level; specifying a ceiling misses the point. The wall must reach enough, not just stay under a limit.
“The most overlooked item is minor.” — Service direction, the permitted access and the enclosure class are the items most often missing, and each becomes a fault on site if left out.
A note for the supplier: specification checklist before buying
Build the specification as a checklist before ordering: environment class and mounting, pitch from the closest viewing distance and content, brightness for the real light level, the permitted service direction, control and content workflow, and written acceptance criteria. Capturing these on one page turns a vague brief into a testable order and prevents the expensive mismatches that appear only after cabinets are on site.