For a new build, the architect's full-service fee (SIA phases 31 to 53) is typically between 12 % and 18 % of the effort-determining construction costs; renovations are higher in percentage terms, often 15 % to 22 %. This is governed by the SIA ordinance 102, 2020 edition — not a state regulation but an industry recommendation of the SIA, which is nevertheless agreed as a contractual component in virtually every architect's contract. It names three fee models (lump sum, time, construction costs), relies for the phase model on the SIA standard 112 with 6 main phases and 11 sub-phases, and also governs the most common contractual pitfalls.
Since the 2020 revision, the SIA ordinance 102 names three models: lump-sum fee (fixed amount in advance, low price risk with a clean service description), time-based fee by actual hours worked (ideally with a cost ceiling and open accounting beneath it) and the construction-cost fee. The latter couples the fee to the effort-determining construction costs — tricky, because it creates an incentive for higher construction costs. A proven mix for large projects: lump-sum fee for the design work (phases 31 to 33), time-based fee with a cost ceiling for realisation.
Until the end of 2019, the SIA published binding Z-values (Z1, Z2) for calculating the fee based on effort-determining construction costs. Following an intervention by the Competition Commission (WEKO), Article 7 "Fee calculation based on effort-determining construction costs" was deleted without replacement in the 2020 edition — the calculation formula can no longer be published under competition law. Many firms, however, still use the model as an internal calculation basis; it must then be explicitly agreed in the contract. The most sensitive negotiating point remains the difficulty factor n: a change from n = 1.0 to n = 1.1 already means around 10 % higher fees.
A rough, simplified example calculation from the standard: with effort-determining construction costs of CHF 800'000 (excluding land, connections, fees), fee class 3 and factor n = 1.0 for a single-family house with standard finishing, a fee share of approx. 12 % to 18 % yields a fee of roughly CHF 96k to 144k for the full service 31 to 53. The range is wide and strongly negotiable; site management alone accounts for approx. 30 % — anyone who outsources it saves accordingly.
The SIA knows three accuracy levels: cost estimate ±25 %, cost projection ±10 % and detailed cost projection ±5 %. If an overrun lies within the 10 % tolerance limit, the Federal Supreme Court (cf. BGE 4A_271/2013) presumes that the architect did not act negligently — the client bears the additional costs. Above 10 % the burden of proof reverses: the architect must show that he estimated and monitored the costs carefully. Without an agreed accuracy level, the Federal Supreme Court presumption applies that additional costs of up to 10 % are to be borne by the client.
For the construction-cost fee, the SIA ordinance weights each sub-phase with a percentage share of the total fee — structured into preliminary project (31), construction project (32), permit (33), tendering (41), execution planning (51), execution (52) and completion (53). These shares were previously published (2014 edition) and remain common in industry practice; they help to delineate partial services cleanly. In sum, the realisation phases 51 to 53 make up around 50 % of the fee. Anyone who hands site management to a general contractor can renegotiate this share with the architect.
Your own architect costs 12 % to 18 % of the construction costs, offers high cost transparency (individual awards, cost estimate per trade) and a low insolvency risk (many individual contracts). The GU package works with a fixed price including margin (typically 8 % to 15 %), often delivers standard houses in under 12 months, but carries a high insolvency risk: in the event of a GU bankruptcy during construction, money already paid falls into the bankruptcy estate, while unpaid tradespeople secure themselves via the construction craftsmen's lien (OR Art. 837 ff.) on the property. Many combine both as a hybrid model — your own architect for phases 1 to 4, a GU contract for realisation.