The OOH Media Buying Process: What to Expect

Out of home is the only major channel where you cannot simply decide to buy something and have it live that afternoon.

That surprises people coming from digital. They are used to self-serve, instant inventory, and the ability to change creative mid-flight. Out of home is a physical supply chain with a calendar, a print run, a crew, and a finite number of places where an advertisement can exist.

Once you accept that, the process makes sense and it becomes quite predictable. Fight it, and you spend every campaign discovering the same constraints late.

This is a walkthrough of what the out of home buying process actually involves, phase by phase, what each stage is really for, how long things take, where campaigns commonly go wrong, and how the unconventional side of the channel fits alongside the conventional side.

I come at this from the delivery end rather than the planning end. I run poster, decal, projection, truck and street team campaigns, which means I spend most of my time in the part of out of home that does not have an availability calendar. That gives me a slightly different view of the buying process than a pure media planner would have, and I think it is a useful one.

Two different supply systems under one name

The first thing to understand is that out of home is not a single market. It is two, and they behave completely differently.

Inventory-based out of home. Billboards, transit, street furniture, mall and airport panels, digital screens. Someone owns these, they are catalogued, they have availability calendars, audience measurement is applied to them, and you buy a slot for a period. The whole system is designed around booking.

Non-inventory formats. Poster Campaigns on hoardings and private walls, Snipe Advertising, sidewalk decals and stencils, projection, LED Trucks, Street Teams. None of this is catalogued. There is no availability calendar because there is no inventory. You find surfaces, establish who controls them, secure permission, and execute.

The buying process for the first is a booking process. The buying process for the second is a sourcing and permission process. People routinely apply the mental model of the first to the second, and that is where timeline expectations go wrong.

Most strong campaigns use both. Inventory formats give you scale, measurement and predictability. Non-inventory formats give you density in specific corridors, street-level texture and places where inventory does not exist.

Phase one: the brief, and what actually needs to be in it

Everything downstream is shaped by this, and most briefs are missing the same three things.

What a usable out of home brief contains.

A testable objective. Specific enough that someone could tell afterwards whether it happened. Awareness in a defined area over a defined window. Footfall to specific locations. Support for a launch date. “Build brand” is not plannable.

Geography at the right resolution. Not a list of cities. Districts, corridors, approaches, catchments. Out of home is a geographic medium and a brief that specifies geography loosely produces a plan that is spread too thin to register.

The audience, described by where they are rather than who they are. Demographic profiles are less useful here than behavioural geography. Where do these people walk, commute, queue, socialise, work?

Dates, and which of them are immovable. There is usually one fixed date and several that are assumed to be fixed but are not. Knowing which is which creates planning room.

Constraints. Creative that already exists, brand rules, categories or locations to avoid, approvals that will be slow internally.

How success will be measured. Decided now, not later.

Benchmark: one primary objective. A brief with five objectives produces a plan that serves none of them.

Phase two: planning and format selection

The planner’s job is to turn the brief into a format and geography recommendation, and this is where the two supply systems get balanced.

For inventory formats, the work is checking what exists in the target geography, what is available in the window, and what the audience data says about it. Availability is a real constraint. Good locations in strong markets get booked well ahead, and the best sites in high-demand periods are often gone months in advance.

For non-inventory formats, the work is different. Somebody has to establish what is physically on those streets. That means a survey: walking the corridors and documenting surfaces, condition, sightlines, orientation, night lighting, and the best available read on who controls each one.

This cannot be done from a desk. Mapping imagery goes stale, construction hoardings appear and disappear on a timescale of weeks, and obstruction and eye line are invisible from above.

The survey frequently changes the format recommendation. A corridor with poor wall stock but excellent flat unlit facades is telling you it is a projection market. A sprawling area with a small walkable core and heavy vehicle traffic is telling you to run a truck route with a poster cluster rather than a poster campaign.

Benchmark: let the streets inform the format. Clients usually arrive with the format chosen, and sometimes the survey disagrees.

Second benchmark on geography: concentration beats coverage, consistently. Density is the mechanism by which out of home registers. A useful test is whether someone on foot could plausibly encounter the campaign several times in a normal week without going out of their way.

Phase three: availability, proposals and what to interrogate

For inventory, you receive a proposal: locations, formats, periods, audience estimates.

The thing to interrogate is the audience numbers, because they are modelled rather than counted. Out of home impressions are built from traffic and pedestrian counts, population layers and a visibility assumption, and that last element is where the variance lives. Two proposals can produce very different totals from similar locations because they used different assumptions.

So compare locations, not headline totals. Where exactly is the panel? What faces it? What is the approach? Is it visible from the direction people actually travel? Is it obstructed at the time of year the campaign runs, when trees have leaves?

Site visits matter more than planners sometimes admit. A panel that looks strong in a database can be hopeless in person.

For non-inventory work, there is no availability to check, so the equivalent phase is permission. This is the long pole of the entire process.

The work is identifying the controller of each surface worth having, reaching the right person at an owner or managing agent, and securing documented consent naming the surface, the scope and the period. Some come back in a day. Many take over a week. Some never respond.

Benchmark: survey meaningfully more surfaces than the plan needs, because permission will not convert on all of them and some surfaces change before install. Going into this phase with a candidate list the same size as the target placement count is how campaigns end up thin.

Benchmark: start permission the day geography is confirmed, running in parallel with creative rather than after it. It is the only phase whose duration you do not control.

Phase four: booking, commitment and the permission reality

For inventory, booking commits you. Cancellation terms, creative deadlines and production specifications all land at this point, and the dates in them are real.

For non-inventory, the equivalent commitment is the confirmed permission set, and this is where the risk profile of the campaign is actually set.

I want to be accurate about this rather than reassuring. Posting, decals, projection and street activity sit in genuinely uneven territory. Rules vary by municipality and arrive through different routes: signage codes in one city, property maintenance provisions in another, sidewalk rules or vehicle parking and standing rules elsewhere. Enforcement is inconsistent and differs between districts and across seasons.

I am not going to tell you whether something is permitted in your market. That depends on the municipality, the specific surface and who controls it, and those determinations belong with your own counsel.

What I will tell you is that the decisive controllable factor is surface ownership and documented consent. Work on a private surface with the controller’s written agreement, properly documented, with a removal commitment attached, sits in a very different position from improvised placement. We build location lists around established surface control, and any surface whose controller we cannot identify does not enter the plan.

That is the real difference between a non-inventory campaign that behaves predictably and one that does not.

Phase five: creative specifications and production

This phase catches people out because the specifications are unforgiving and the deadlines are fixed by physical production.

For inventory formats, each panel type has its own dimensions, bleed, resolution and material requirements, and digital screens have their own file and duration rules. Deadlines are set by the production and posting schedule, and missing one usually means missing the start of the flight.

For non-inventory, production lead times vary by format. Paper for pasting is relatively quick. Pavement-rated adhesive graphics take longer. Fabricated elements for an activation take longest and should be prototyped before the full run.

Across everything, the creative requirement is the same and it is brutal. The work will be seen for a couple of seconds, often at an angle, frequently in poor light, surrounded by visual noise, by someone thinking about something else.

What survives: large simple forms, high contrast, very few words, one idea, a brand mark readable at distance.

What fails: small type, mid-tone palettes that dissolve in daylight, detailed illustration, long copy, URLs with paths in them, and QR codes placed where nobody can stop safely.

Benchmark: print it at size, take it outdoors, and look at it from the distance people will actually be at. A lot of work fails this test, and at that stage the fix is cheap.

Benchmark: order an overage. Crews lose material to damage, misapplication and weather, and running out on the final night of an install is avoidable.

Phase six: scheduling against the city and the weather

Out of home runs in physical conditions and the schedule has to respect them.

The city calendar moves the right dates. University terms empty campus corridors between them. Sports seasons, convention weeks and festivals either are the opportunity or are a reason to stay away because streets are closed. Public holidays hollow out business districts. Construction programmes change what surfaces exist.

Then the weather window, which is a physical constraint.

Paste needs workable temperature and a curing window. Installed in near-freezing conditions the bond does not form properly and work can be on the pavement by morning. Rain during curing is the main threat, while rain afterwards is far less damaging than people expect. High heat flashes moisture off too fast. Sustained UV fades inks, so in high-sun markets the visual life of a campaign is shorter than its physical life.

Sidewalk graphics fail through abrasion rather than weather. Foot traffic grinds them down and winter grit and salt accelerate it sharply, with doorways and crossings failing first.

Projection needs darkness and a pale, flat, unlit surface. A dark glass facade with floodlighting on it is not a screen.

LED panels are a different product by day and night. In direct sun contrast drops and creative has to be simple to survive. After dark the panel is the brightest thing on the street.

Benchmark: every install schedule gets a contingency night agreed up front. It costs nothing to plan and it saves campaigns.

Phase seven: install, posting and proof

For inventory formats, posting happens on the schedule and you should receive proof of posting: photographic evidence that your creative is up, at the specified locations, on the specified dates. Check it. Panels do get posted late, posted wrong, or posted with the wrong creative, and the proof set is how you find out.

For non-inventory work, install is a crew operation.

A poster crew working a mapped, permissioned route is typically two to four people, moving in planned sequence from late evening into the early hours. Night work is practical: sidewalks are clear, the vehicle can get close, and nobody is working around pedestrians. A compact well-permissioned district covers in a small number of consecutive nights, while the same number of placements scattered across a metro takes considerably longer because most of the shift becomes driving.

Sidewalk decals run early morning, needing a clean, dry, clear surface. Projection is an evening operation constrained by power and sight line. LED truck shifts follow the audience, a driver per vehicle with a second person where positioning or documentation justifies it. Street teams work in day parts with a named lead on site.

Benchmark on documentation: every placement photographed, timestamped, with enough surrounding context to identify the location, mapped against the approved list. Full coverage, not a curated sample. For truck work, route logs with a short GPS fix interval and dwell time broken out by target zone, with transit time shown separately.

Phase eight: in-flight management, make-goods and removal

Things go wrong during a flight and the process has mechanisms for it.

On inventory, a panel can be obstructed by new construction, damaged, or go dark on a digital screen. The remedy is usually a make-good: extended time or a replacement location. You only get this if somebody is checking, which is an argument for not filing the proof set unread.

On non-inventory, the equivalents are material degradation, placements covered over by others, and surfaces that change mid-campaign. Long campaigns may need a refresh pass, and that is crew time that belongs in the plan.

Removal is the phase most often left out. It is real scheduled work with a named owner and a date, and the expected surface condition should be agreed before install rather than negotiated afterwards. Material left to degrade generates complaints, and complaints are what change local climates for everyone operating in that city.

Benchmark: removal has a date and an owner in the plan before the campaign goes live, or it will not happen.

What goes wrong across the whole process

Starting too late. The dominant failure. Inventory availability disappears and permission cannot be compressed.

Spreading too thin. More locations feels like better value and produces a campaign nobody registers.

Treating modelled audience figures as measured results. They are planning and comparison tools built on assumptions, not counts.

Creative approved on a screen. It passes internal review and reads as grey mush from across the road.

Missing a production deadline. Pushes the install into a worse window or off the flight entirely.

No measurement owner. Nobody builds the landing path or issues the codes, and afterwards nothing is attributable.

Not checking proof of posting. Errors go unremedied because nobody looked.

No removal plan. Small saving, disproportionate downstream cost.

What we talk clients out of

Buying broad coverage instead of depth. I regularly halve a footprint and double the concentration, and the campaign performs better.

Locking a date before checking availability and permission feasibility. If the date is genuinely immovable, the plan has to be built from what can clear in time.

National rollout before proving one market. Ten markets built on assumptions repeats one mistake ten times at once.

Choosing the format before surveying the streets.

Judging proposals on headline impression totals. Compare locations and sightlines.

Buying inventory alone in a corridor where the brand needs to feel native. This is the one I argue most. Inventory formats put you above the street. They deliver reach and they are measurable, and they also read as bought media, because they are. Where a brand needs to feel like it belongs in a neighbourhood rather than having been placed into it, Wheatpasting & Poster Campaigns in the same corridors does something inventory cannot. Run both and they compound: the panels deliver the reach, the posters deliver the texture and the repetition at eye level on the walk to the station.

Skipping the physical survey. It is the cheapest insurance in the process.

Frequently asked questions

Request a campaign quote

If you are planning out of home activity and want the inventory and non-inventory sides considered together rather than separately, tell us the markets, the corridors, the audience, the objective and the dates you are working towards.

We will come back with a format recommendation grounded in what is physically on those streets, a surface and permission approach, a realistic schedule with the long poles in the right place, production requirements, a documentation standard and a removal plan. We will also tell you what we would cut.

Request a campaign quote and we will start with the streets rather than the rate card.