What the APS stage is for
APS follows the client's approval of the concept design. It deepens the project on three fronts at once: architectural, in the precision of the drawings; technical, in the choice of construction systems; and economic, in the structuring of the estimate.
At APS the design team produces a provisional estimate of the forecast works cost (R2431-10). It does not commit yet: in public procurement, where its appointment includes assistance with awarding the works contracts, its commitment bears on the forecast cost settled no later than the launch of the works tender (R2432-3). The APS estimate prepares that commitment: an optimistic figure can be paid for at tender, through rework at no extra fee that the client may then require, on the conditions set out below.
APS and APD: where the line falls
| APS: what is settled | The construction system, concrete, timber or steel, façade types, the routing of services, final areas confirmed, the major choices among the finishing trades. |
|---|---|
| APS: what stays open | The detail of individual elements, precise material specifications, the sizing of services, joinery details. |
| APD: what will be settled | All the technical detail needed to support the planning application and to launch production of the written documents in the PRO pack. |
The APS deliverables
Architectural deliverables
- ℹ Floor plans, sections and elevations at 1:100 to 1:200: precise enough to characterise the project architecturally. Openings are located, floor-to-ceiling heights are stated, circulation is drawn.
- ℹ Outline description: a description by trade of the materials and methods envisaged, for instance reinforced concrete frame, accessible flat roof, thermally broken aluminium joinery, external wall insulation.
- ℹ Preliminary fire safety note: where the project is a public-access or high-rise building, a preliminary note is produced to anticipate the regulatory constraints.
Consultants' cost deliverables
- ℹ APS estimates for the technical packages: the structural, mechanical and electrical consultants produce their estimates in step with the architectural assumptions that have been settled.
- ℹ Target cost by technical package: an internal working document confirming that the package envelopes hold together within the overall envelope.
The principal cost deliverable: the APS estimate
The APS estimate is the economic centre of the stage. It is structured by trade or by functional element, unlike the ESQ, which used global ratios per square metre. That structure makes the cost items visible and allows trade-offs to be prepared if the envelope is exceeded.
A typical APS estimate structure
Earthworks and external services: excavation, foundations, external networks, landscaping. 5 to 12 % of the works cost depending on the site.
Structural works: reinforced concrete frame, loadbearing masonry, roof structure, ground-bearing slab. 25 to 35 % of the works cost.
Roofing and waterproofing: flat roof, pitched roof, rooflights. 3 to 7 %.
Façades and external joinery: renders, cladding, external wall insulation, aluminium, timber or PVC joinery. 8 to 15 %.
Plasterwork, insulation and partitions: internal partitions, linings, suspended ceilings. 6 to 10 %.
Internal joinery and fitted furniture: internal doors, cupboards, kitchen fit-out. 3 to 6 %.
Floor and wall finishes: tiling, timber flooring, paint, wall tiles. 5 to 9 %.
Mechanical and plumbing: heating, ventilation, cooling, hot water, sanitaryware. 8 to 15 %.
Electrical, power and data: distribution boards, cabling, lighting, data, security. 6 to 12 %.
Lift, where applicable: 50,000 to 80,000 € excluding VAT per lift depending on configuration.
The accuracy of an APS estimate is in the region of ±15 to 20 %. That is markedly better than ESQ, but it remains wide. The technical choices sharpened at APD will bear directly on the final cost.
The design team's commitment to the forecast cost
In public procurement, APS produces a provisional estimate of the forecast cost (R2431-10), with no commitment. The commitment comes later, on the forecast cost settled no later than the launch of the works tender (R2432-3), with a tolerance set by the design appointment (R2432-2). Where the appointment's particular documents say nothing, and only if the appointment refers to the 2021 CCAG-MOE, its article 13.2 calculates that tolerance with a formula in euros excluding VAT: forecast works cost x 1.05 for new build, x 1.1 for refurbishment. The threshold therefore sits 5 % or 10 % above the forecast cost: it is a ceiling on overrun, not a plus-or-minus band.
If tenders exceed that cost beyond the tolerance, the client can ask the design team to adapt its studies at no extra fee (R2432-3). For design appointments whose tender was launched, or contract notice sent for publication, on or after 1 January 2023, it can only do so if the overrun does not result from circumstances the design team could not foresee; the earlier wording set no such condition (decree no. 2022-1683, art. 3 and 8). A fee reduction only follows the second commitment: where its appointment also includes site direction and assistance with handover, the design team commits to the cost resulting from the works contracts, checked after the works are complete; if that new tolerance is exceeded, its fee is reduced, by up to 15 % of the fee for the assignment elements after award of the works contracts. For the same design appointments, tendered on or after 1 January 2023, only an overrun resulting from a failing in those two duties triggers the reduction (R2432-4). It is therefore fundamental that the APS estimate be realistic rather than optimistic.
ℹ The trap of an under-stated APS estimate An APS estimate deliberately set low, to reassure a client or to win a commission, sets off a cascade. At APD the measured quantities reveal the gap against the APS estimate, forcing either a change of design or an admission of overrun. At tender the contractors' bids confirm the gap, producing friction with the client, a renegotiated appointment, sometimes an abandoned project. And in construction, if the project proceeds on an insufficient envelope, the specification is cut, the finishing trades are degraded, and disputes follow. An honest APS estimate is the construction economist's first act of professionalism.
APS and APD side by side
| Level of technical definition | APS: the major options, concrete or timber, external or internal insulation, centralised or local mechanical systems. APD: precise technical choices with the sizing data the planning application requires. |
|---|---|
| Accuracy of the estimate | APS: ±15–20 % by trade. APD: ±10 %, the definitive estimate of the forecast cost. |
| Documents produced | APS: drawings at 1:100 to 1:200, outline description. APD: drawings at 1:100, complete outline specification, planning file. |
| Contractual commitment | APS: provisional estimate, no commitment. APD: definitive estimate; in public procurement, the forecast cost the design team commits to can be settled at this stage, as its appointment provides, and no later than the launch of the works tender (R2432-2 and R2432-3). |
| Planning application | APS: no complete planning file yet. APD: the planning file is included or being finalised. |
APS on refurbishment projects
On refurbishment work, APS begins after the technical surveys of the existing building: structure, asbestos, lead, existing electrical installations. Those surveys are not part of the core appointment and must be commissioned separately by the client.
An APS estimate on a refurbishment is structurally more uncertain than on new build. The hazards of an existing building, what is discovered once work starts, the real state of the structure, the presence of hazardous materials, can generate costs nobody could foresee. The contingency must be larger than on new build, generally 10 to 20 % of the works cost.
Sources: Léonard Hamburger, Maître d'œuvre Bâtiment, 3rd ed., Eyrolles, 2016 · MIQCP fee guide.