Concept Design vs. Technical Specification: What Public Buyers Need to Know

Public playground projects rely on two documents that are used almost as often as they are confused with one another: the concept design and the technical specification. These are not two versions of the same thing, an early sketch followed by a polished final version. They are two distinct documents that serve two distinct roles at two distinct stages of a project.

The concept design exists to help people agree on an idea. It shows what the playground could look like, how the space might be laid out and what kind of experience the project is aiming for. It is the document that helps a city council, a school board or a group of residents visualise the project and say they want to move forward.

The technical specification exists to turn that idea into something a public procurement process can act on. It converts an approved concept design into measurable, verifiable requirements that a supplier can be contractually bound to, and that a public buyer can use to run a fair, comparable tender.

For public buyers, understanding this distinction early matters more than it might first appear. Confusing a concept design with a specification is one of the most common causes of delay and dispute in public playground procurement.

A concept design is the visual and narrative starting point of a playground project. It is typically produced early, often before the budget has been finalised, and its core purpose is to help stakeholders visualise the project and agree it is heading in the right direction.

What a concept design typically includes

A concept design typically shows the visual layout of the site: how the play zones relate to one another and to existing paths, seating, greenery and access points. It shows a spatial arrangement rather than a fixed plan, giving a sense of scale and flow rather than exact dimensions. It suggests general equipment types and thematic zones without committing to a specific product, model or manufacturer. Most importantly, a concept design conveys an impression of how the space will feel to a child, a parent and the community. All of this is meant to align stakeholders and the public around a vision and scope, not to define exactly what will be built down to the last measurement.

What a concept design cannot do

A concept design is not a binding document. However polished the visuals, however detailed the layout looks, it does not contain the measurable requirements a supplier could be held to under contract. It does not define exact dimensions, load capacities, material composition, safety performance or documentation obligations. It is not written to withstand the scrutiny a public procurement process requires.

That means a concept design, however finished it looks, is not enough to run a tender on its own. A visually polished concept design can create a false sense of readiness. It is easy to look at an attractive rendering and assume the project is close to going out to tender, when in reality the technical groundwork the tender actually depends on has not yet been produced.

A technical specification is the document that turns an approved concept design into something suppliers can actually bid on. It is built on measurable, verifiable requirements rather than impressions.

What the specification adds that the concept design does not

Where a concept design shows a generic climbing structure, the specification defines the equipment's functions and dimensions. Where a concept design suggests a material palette, the specification defines the materials themselves, together with the safety requirements the equipment must meet under EN 1176, and the surfacing requirements under EN 1177. It also defines the scope of installation and the documentation and warranty terms expected as part of delivery.

A detailed breakdown of what a playground technical specification should cover is available in a dedicated REDOX Academy guide. This article focuses on how the specification relates to the concept design that precedes it.

Why suppliers price bids against the specification, not the concept design

Fair, comparable supplier bids depend on a document with measurable requirements. Suppliers need to know exactly which equipment functions are required, which materials and safety performance are expected, and what installation and documentation obligations they are taking on. A concept design, by its nature, does not contain that level of detail. If suppliers are asked to price a bid from the concept design alone, they are left guessing at requirements that were never actually defined, which makes bids difficult or impossible to compare on equal terms.

Most of the difficulties that surface later in a playground project trace back to an early moment when the concept design was treated as more finished, or more binding, than it actually was.

The approved picture trap

A common scenario looks like this: a concept design is presented to a city council, a board or a public consultation, is well received, and is formally approved. From that point, everyone involved can reasonably assume the project is ready for procurement. What often goes unnoticed is that approving a concept design only confirms the project's vision and scope. It does not create the measurable detail a tender needs. That gap only becomes visible once someone actually tries to write the tender documentation and realises the concept design does not answer the questions suppliers will ask.

The consequences of skipping the specification stage

When a project moves towards a tender without a properly developed technical specification, a handful of problems tend to follow. Timelines stretch, because the specification work has to happen regardless, just later and under more pressure. The project scope becomes unclear during the tender process itself. Bids become difficult to compare, because without shared, measurable requirements, each supplier can interpret the concept design differently and price a different project. Disputes can surface later over what the contract actually promised versus what the original concept design merely illustrated.

None of this means the concept design is unnecessary, or that it should be skipped in favour of going straight to the specification. The two documents are meant to work together, one after the other.

The typical sequence

In a typical public playground project, the concept design comes first. Its job is to align stakeholders around a vision, layout and general scope, and it is often the document used for public consultation, community engagement or initial budget approval. Once the concept design is approved, the technical specification follows, turning it into a binding, tender-ready document that suppliers will actually respond to.

What can, and cannot, change between the two stages

It is normal, and expected, for certain things to change between the concept design stage and the specification stage. As feasibility studies are completed, the budget is finalised, site conditions are properly assessed, and applicable standards and documentation requirements are worked out, adjustments to the original concept design are a normal part of good project development.

What should not change, however, is the underlying intent and scope stakeholders agreed on. The specification is not a formality that must confirm everything the concept design showed, but it should not become an entirely different project either. Its job is to translate the approved vision into something that can actually be built, procured and verified.

Questions to ask before moving from concept design to specification

Before a project moves from an approved concept design into drafting the specification, it is worth pausing to check that a few basics are genuinely in place: Has the concept design been formally approved? Has a budget range been established? Has the site been assessed for conditions that could affect equipment, surfacing or installation? Has someone been specifically assigned to turn the concept design into a specification? And is it clear which standards apply, including EN 1176 for equipment and EN 1177 for surfacing?

This list is offered as a general guide, not as a substitute for local procurement regulations or legal advice. Public procurement procedures and documentation requirements vary by country and project type.

REDOX operates across the full project chain, from early concept design conversations through to manufacturing and installation. At the concept design stage, REDOX can provide expert advisory input, helping a public buyer think through a realistic project scope, suitable materials and how a proposed layout fits an actual site, without steering the outcome towards a specific product or a predetermined solution.

Later, as the project moves towards tender, REDOX can help translate an approved concept design into functional, verifiable specification language, wording that describes what the equipment must do and meet rather than naming a specific product, in keeping with a tender-neutral approach that keeps the process open and fair to all suppliers.

Cities, municipalities and public buyers are welcome to send REDOX their project idea or concept design, whatever stage it is currently at, for an initial conversation about what documentation is needed for the next step.

What should a playground technical specification include? What should public investors prepare before starting a playground project? How do you plan a playground, from idea to installation?