HOAI, VOB, GAEB, AVA, audit-proof record keeping: the key terms of planning and building, explained briefly, correctly and in relation to your task.
The German fee scale for architects and engineers, governing how fees for design services are calculated in Germany.
HOAI (Honorarordnung für Architekten und Ingenieure) is a German regulation that governs how fees for design services are calculated. It organizes services into service profiles and service phases 1 to 9 (LP 1–9) and sets the fee from the chargeable costs, the fee rate and a fee table. Current version: HOAI 2021.
The nine phases of a design commission under HOAI, from basic evaluation to project support.
Service phases divide a design commission under HOAI into nine steps: LP 1 basic evaluation, LP 2 preliminary design, LP 3 design, LP 4 approval planning, LP 5 execution planning, LP 6 preparation of contract award, LP 7 assisting the award process, LP 8 construction supervision, LP 9 project support. Each phase is assigned a percentage of the total fee.
A method for calculating the fee between the reference points of the HOAI fee table.
The HOAI fee tables state fees only for specific cost reference points. When the chargeable costs fall in between, the fee is interpolated linearly (§ 13 HOAI). Structify performs this interpolation automatically and traceably.
The German procurement and contract rules for construction works, covering the award and handling of construction contracts.
VOB (Vergabe- und Vertragsordnung für Bauleistungen) consists of three parts: VOB/A (award), VOB/B (contract execution, including change orders and acceptance) and VOB/C (general technical contract terms). In Germany it is the basis for many construction contracts, especially with public clients.
The German standardized data exchange format for tendering, award and billing in construction.
GAEB (Gemeinsamer Ausschuss Elektronik im Bauwesen) defines an XML exchange format for bills of quantities and bids. The file stages run from .X81 (bill of quantities) through .X83 (request for bids) to .X84 (bid). Structify imports and exports GAEB XML cleanly in the standard format.
Tendering, award and billing of construction works.
AVA stands for tendering, award and billing (Ausschreibung, Vergabe und Abrechnung): the three steps in which construction works are described, awarded to bidders and billed after completion. Its core is the bill of quantities (BoQ); bids are compared using the bid comparison.
A structured list of all construction works to be tendered, with quantities and descriptions.
A bill of quantities (BoQ) describes the construction works to be delivered as individual items, each with a quantity, a unit and an item description. It is the basis for the tender and the later comparison of bids. BoQs are usually exchanged as a GAEB file.
A tabular comparison of several bids item by item, to support the award decision.
A bid comparison sets the bids from several bidders side by side, item by item. It makes price differences, outliers and gaps visible and serves as the basis for a documented award recommendation.
A systematic on-site check of a construction project.
A site inspection is the planned walk of a construction site to record progress, defects and open points and to document them. The result is a site inspection report. Structify creates this report from voice, photo and note. You can record without a connection; the analysis runs once your data has synced.
A running record of what happens on site each day.
A site diary (daily construction log) documents construction progress, weather, the personnel and equipment on site and any special events, on every working day. It serves as evidence, for example in change orders or disputes, and should be kept gap-free and auditable.
A deviation of the work from its contractually agreed condition, and the formal notice of it.
A defect exists when construction work deviates from the agreed or customary condition. With a notice of defects, the client reports the defect and sets a deadline for remedy. Structify recognizes defects in photos, pins them on the drawing and tracks deadlines into the warranty period.
An additional or changed service compared with the original construction contract.
A change order (Nachtrag under VOB/B) arises when services are added or changed during construction. For VOB contracts, the payment is determined under VOB/B Section 2. Change orders should be identified early, calculated traceably and drafted in a formally sound way.
The legal approval of construction work as substantially in line with the contract.
With acceptance, the client declares that the construction work has been delivered substantially in line with the contract. It is pivotal: among other things, it triggers the start of the warranty period, the due date of the final payment and the shift of the burden of proof.
Liability for defects after acceptance, within the limitation period.
Under warranty, the contractor is liable for defects that arise or appear after acceptance. The limitation periods differ by contract (BGB or VOB/B). Gap-free documentation supports claims in a dispute.
Tamper-proof, traceable and complete retention of documents.
Audit-proof record keeping (Revisionssicherheit) means that documents are stored so that they are complete, tamper-proof, traceable and retrievable. For tax-relevant records, the GoBD (the German principles for proper electronic bookkeeping and records) set out these requirements in detail. Structify Operate locks operating entries after approval; the maintenance log cannot be edited afterwards.
The German principles for proper management and retention of books and records in electronic form.
The GoBD are administrative rules of the German tax authorities for the proper management and retention of tax-relevant electronic records and documents. Among other things, they require traceability, tamper-proofing and completeness.
Continuous digital capture, structuring and filing of all records across the construction process.
Digital construction documentation is the capture, without re-keying, and structured filing of all records along the construction process, from site inspection through defects and the site diary to acceptance. The goal is auditable, retrievable documents instead of scattered notes and photos.
The part of the construction costs that forms the basis for calculating the design fee under § 4 HOAI.
Chargeable costs (anrechenbare Kosten) are the part of the costs of constructing, converting, modernizing, maintaining or repairing an object that enters the fee calculation; VAT is not included (§ 4 paras. 1 and 2 HOAI 2021). They are determined by the cost groups of DIN 276 (for the HOAI, the edition DIN 276-1:2008-12 applies, § 4 para. 1 sentence 3 HOAI); for buildings, § 33 HOAI counts mainly the costs of the structural works (cost group 300) and, in part, the technical systems (cost group 400). The decisive figure is the cost calculation (Kostenberechnung) or, if none exists, the cost estimate (Kostenschätzung) under § 6 para. 1 HOAI. Structify calculates the HOAI fee from the chargeable costs with interpolation under § 13.
The classification of an object by its planning requirements into fee zones I to V under § 5 HOAI.
Fee zones (Honorarzonen) classify objects by their degree of difficulty (§ 5 HOAI 2021): for buildings from fee zone I for very low to fee zone V for very high planning requirements (§ 35 para. 1 HOAI); building services (Technische Ausrüstung) have only zones I to III (§ 56 HOAI). The zone is assigned using the object lists in the HOAI or by scoring the evaluation criteria with points (§ 35 HOAI for buildings). At the same chargeable costs, the fee rises with the fee zone because each zone has its own range in the fee table. In the Structify HOAI fee calculator, the fee zone is selected and the fee is interpolated under § 13 from the matching table range.
The value within the range of the HOAI fee table between the base fee rate and the upper fee rate (§ 2a HOAI).
For each fee zone and cost level, the HOAI fee tables state a range from the base fee rate (Basishonorarsatz, the lower value) to the upper fee rate (oberer Honorarsatz) (§ 2a HOAI 2021). Since HOAI 2021 these values serve only as fee orientation: following the judgment of the Court of Justice of the EU of 4 July 2019 (C-377/17), minimum and maximum rates are no longer binding and the fee can be agreed freely. If no fee agreement in text form exists, the base fee rate is deemed agreed for basic services (§ 7 para. 1 HOAI). Structify calculates the fee for the selected fee rate with interpolation under § 13 HOAI.
Design services that go beyond the basic services of a service profile and must be agreed separately (§ 3 para. 3 HOAI).
Basic services (Grundleistungen) are the services generally required to properly perform a design commission; special services (Besondere Leistungen) come on top and must be agreed expressly (§ 3 paras. 2 and 3 HOAI 2021). The annexes to the HOAI list them by service phase as examples, such as a survey of the existing building (Bestandsaufnahme, LP 1), a cost-effectiveness calculation (LP 3) or setting up a payment schedule (LP 8) in Annex 10 for buildings; the list is not exhaustive. Their fee is agreed freely and is not derived from the fee table (§ 3 para. 3 HOAI).
A planning discipline under the HOAI whose basic services are structured into service phases (§ 3 para. 2 HOAI).
A service profile (Leistungsbild) groups the basic services of a planning discipline and structures them into service phases (§ 3 para. 2 HOAI 2021). In addition to area planning (Flächenplanung, Part 2), in object planning the HOAI covers the service profiles buildings and interiors (§ 34, Annex 10), open spaces (§ 39, Annex 11), engineering structures (§ 43, Annex 12) and traffic facilities (§ 47, Annex 13); in specialist planning, structural design (§ 51, Annex 14) and building services (§ 55, Annex 15). Each service profile has its own fee tables, fee zones and percentages per service phase; for buildings, for example, 25 % falls on execution planning (LP 5) and 32 % on construction supervision (LP 8) (§ 34 para. 3 HOAI). Structify calculates fees under HOAI 2021 for these service profiles of object and specialist planning.
The agreement between the contracting parties on the design fee, to be made in text form under § 7 para. 1 HOAI.
The fee for design services follows the agreement that client and contractor make in text form (§ 126b BGB); without it, the base fee rate is deemed agreed for basic services (§ 7 para. 1 HOAI 2021). Unlike under HOAI 2013, the agreement no longer has to be concluded when the commission is placed and is not bound to minimum or maximum rates. Towards consumers, the contractor must point out in text form before the contract is concluded that a fee higher or lower than the table values can be agreed; if this notice is missing, no more than the base fee rate applies (§ 7 para. 2 HOAI). Typical content covers the service profile, the commissioned service phases, the fee zone, the fee rate, the chargeable costs and any special services.
Determination of the quantities of construction work actually performed, as the basis for billing.
The Aufmaß determines the quantities of construction work actually performed, by measuring on site or from drawings; under a unit price contract it is the basis for billing. Under § 14 (2) VOB/B, the findings needed for billing are to be made jointly where possible, as the work progresses (joint measurement, gemeinsames Aufmaß); for work that will be hard to verify once the works continue, the contractor must request joint findings in good time. The billing rules of the individual trades, for example on over-measurement and deductions, are set out in the general technical contract terms of VOB/C (DIN 18299 ff., section 5). A measurement signed by both parties makes it easier to prove quantities in the final invoice and in a dispute.
An invoice for partial work already performed during construction, issued before the final invoice.
With an interim invoice, the contractor requests an interim payment (Abschlagszahlung) during construction, equal to the value of the work performed in line with the contract and evidenced up to that point. Under § 16 (1) no. 1 VOB/B, interim payments are to be granted on request at intervals as short as possible or at the agreed dates; the work must be evidenced by a verifiable statement, and the claim falls due within 21 days of receipt of that statement (§ 16 (1) no. 3 VOB/B). Under a BGB construction contract, the claim follows from § 632a BGB. Interim payments are provisional: they do not count as acceptance (Abnahme) of parts of the work (§ 16 (1) no. 4 VOB/B) and are settled in the final invoice.
The final, verifiable statement of account for all construction work performed, issued after completion.
The final invoice settles all work under the construction contract after completion; interim payments already made are deducted. Under § 14 (1) VOB/B it must be verifiable (prüfbar): clearly structured, following the order of the items and the terms used in the contract, and accompanied by the quantity calculations, drawings and other supporting documents required; changes and additions to the contract must be marked separately. Unless otherwise agreed, for contractual execution periods of up to three months it must be submitted no later than 12 working days (Werktage, Monday to Saturday) after completion; the deadline extends by 6 working days for every further three months (§ 14 (3) VOB/B). After acceptance (Abnahme), the final payment falls due no later than 30 days after receipt of the final invoice (§ 16 (3) no. 1 VOB/B; up to 60 days if expressly agreed); under a BGB construction contract, payment becomes due only once the work has been accepted and a verifiable final invoice has been issued (§ 650g (4) BGB).
An item in the bill of quantities whose execution is still open at tender stage and is only called off later.
An optional item (Bedarfsposition, also Eventualposition) describes work for which it is not yet certain at tender stage whether it will be executed; the bidder quotes a unit price for it, and the client decides only during execution whether to call it off. Under § 7 (1) no. 4 VOB/A, public contracting authorities are as a rule not to include optional items in the specification, because they complicate pricing and can distort the comparison of bids; they are permitted only in justified exceptional cases, for example for additional work that cannot be foreseen with certainty. Unlike an alternative item (Alternativposition), an optional item does not replace a base item (Grundposition) but is added when called off.
The record of a procurement procedure in text form, covering every stage, finding and the reasons for each decision.
The award record (Vergabevermerk) documents a procurement procedure so that the individual stages, the measures taken, the material findings and the reasons for every decision can be traced. Under § 20 (1) VOB/A, the procedure must be documented promptly in text form, including at least the contracting authority, the type and scope of the works, the contract value, the bidders considered and not considered together with the reasons, the reasons for rejecting abnormally low bids and the reasons for the award; for EU-wide procedures, § 20 EU VOB/A and § 8 VgV apply with corresponding minimum contents. For EU-wide procedures, the documentation and the award record must be retained until the end of the contract term and for at least three years from the day of the award (§ 8 (4) VgV); they form the basis for review proceedings and audits. The bid comparison (Preisspiegel) in Structify sets the bids side by side item by item and thus provides a basis for the award record.
Construction work paid by the hours actually worked rather than by unit price or lump sum.
Hourly rate work (Stundenlohnarbeiten) is paid according to the time actually spent, at agreed hourly rates, usually for smaller tasks whose scope cannot be described reliably in advance. Under § 2 (10) VOB/B it is paid only if it was expressly agreed as hourly rate work before it began; its execution must be notified to the client before it starts (§ 15 (3) VOB/B). The hours worked and the materials, equipment and special costs involved are recorded on time sheets (Stundenlohnzettel), submitted daily or weekly; the client must return them certified within 6 working days (Werktage, Monday to Saturday) of receipt, otherwise they are deemed accepted (§ 15 (3) VOB/B). Invoices for hourly rate work must be submitted promptly after the work is finished and at intervals of no more than 4 weeks (§ 15 (4) VOB/B); in a tender, appended hourly rate work may be included only to the extent strictly necessary (§ 7 (1) no. 4 VOB/A).
The contractor's written notice to the client of concerns about the planned method of execution (Section 4 (3) VOB/B).
If the contractor has concerns about the planned method of execution, the quality of materials or components supplied by the client, or the work of other contractors, Section 4 (3) VOB/B requires it to notify the client in writing without undue delay, if possible before work starts. The concerns must be described concretely enough for the client to recognize their consequences; the client remains responsible for its own specifications, instructions and deliveries. A contractor that meets this duty is not liable under Section 13 (3) VOB/B for defects that result from the client's specification or instructions, from materials or components supplied or prescribed by the client, or from the preliminary work of another contractor. Under a BGB construction contract a comparable duty to examine and warn follows from the ancillary contractual duties (Section 241 (2) BGB).
The contractor's prompt written notice that it considers itself hindered in performing the work (Section 6 (1) VOB/B).
If the contractor believes it is hindered in the proper execution of the work, Section 6 (1) VOB/B requires it to notify the client in writing without undue delay; the notice should state the hindering circumstances and their effects. Without a notice, the circumstances are considered only if the client obviously knew both the fact and its hindering effect. Where the hindrance is caused by a circumstance within the client's sphere of risk, by strike or lockout, or by force majeure or other circumstances the contractor cannot avert, the execution deadlines are extended to that extent under Section 6 (2) VOB/B; where one party is responsible for the hindering circumstances, it owes the other party compensation for the proven loss under Section 6 (6) VOB/B, lost profit only in cases of intent or gross negligence. In Structify, hindering circumstances can be recorded as a site diary entry with a photo.
Written record of the acceptance findings, including reservations for known defects and contractual penalties (Section 12 (4) VOB/B).
The acceptance report is the written record (Niederschrift) in which, at a formal acceptance under Section 12 (4) VOB/B, the findings are set down in a joint meeting; each party receives a copy. It must contain reservations for known defects and for contractual penalties, as well as any objections of the contractor. The reservation is decisive: without it, the client loses a forfeited contractual penalty (Section 11 (4) VOB/B, Section 341 (3) BGB) and, under Section 640 (3) BGB, the defect rights in Section 634 Nos. 1 to 3 BGB for defects it knew of at acceptance. Structify provides a template for the acceptance report.
Acceptance in a joint meeting with a written record; under Section 12 (4) VOB/B it takes place whenever one party demands it.
At a formal acceptance, client and contractor jointly establish the condition of the work and record the findings, reservations and objections in a written record; under Section 12 (4) VOB/B it must take place as soon as either party demands it, and each party may bring in an expert at its own cost. It may take place in the contractor's absence if the date was agreed or the contractor was invited with sufficient notice; the result must then be communicated to the contractor promptly (Section 12 (4) No. 2 VOB/B). If neither party demands acceptance and a formal acceptance has not been agreed in the contract, the work is deemed accepted under Section 12 (5) VOB/B after 12 working days (Werktage, Monday to Saturday) from the written notice of completion or 6 working days after the client starts using the work. Under a BGB contract, Section 640 (2) BGB deems the work accepted if the contractor, after completion, has set the client a reasonable deadline for acceptance and the client does not refuse acceptance within that deadline while naming at least one defect; towards consumers this applies only if the contractor pointed out this consequence in text form together with the request for acceptance.
Remedy of a defect by the client or a third party at the contractor's cost after a set deadline has expired without result.
In substitute performance, the client has a defect remedied itself or by a third party and claims the cost from the contractor. It requires a reasonable deadline for remedying the defect that has expired without result: after acceptance this is governed by Section 13 (5) No. 2 VOB/B and, for a BGB contract for work, by Section 637 BGB (Selbstvornahme); an advance on the remedy costs is expressly provided for in Section 637 (3) BGB and is granted for VOB contracts by case law as well. Before acceptance, Section 4 (7) VOB/B requires a deadline combined with the declaration that the contract will be withdrawn once it expires (Section 8 (3) VOB/B), and only after that withdrawal may the client have the defect remedied by others; according to the German Federal Court of Justice (judgment of 19 January 2023, VII ZR 34/20), this termination rule is invalid where VOB/B has not been agreed as a whole. Structify tracks defects with photos and deadlines, so the expiry of a deadline is documented.
Withholding part of the payment as security for contract performance and defect claims, governed in VOB/B by Section 17.
A retention (Sicherheitseinbehalt) is the contractually agreed withholding of part of the payments by which the client secures proper performance and its defect claims (Section 17 (1) VOB/B). Under Section 17 (6) VOB/B each payment may be reduced by no more than 10 percent until the agreed security amount is reached; the withheld amount must be notified to the contractor and paid within 18 working days (Werktage, Monday to Saturday) of that notice into a blocked account (Sperrkonto) set up for both parties, otherwise the contractor may, after a grace period has expired without result, demand immediate payment and no longer has to provide security (Section 17 (6) No. 3 VOB/B). The contractor may replace the retention with another security under Section 17 (3) VOB/B, for example the surety (Bürgschaft) of an admitted credit institution or credit insurer (Section 17 (2) VOB/B). An unused security for defect claims must be returned after two years under Section 17 (8) No. 2 VOB/B, by the prevailing view counted from acceptance, unless a different return date was agreed; to the extent that the client's claims are still unsettled at that time, it may retain a corresponding part.
The written record of a site meeting, listing participants, findings, decisions, deadlines and responsibilities.
Site meeting minutes (Baubesprechungsprotokoll) record who attended a site meeting, what status was established and which tasks were agreed, with deadline and responsible party. Chairing and recording site meetings is attributed to construction supervision (LP 8); Annex 10 HOAI (buildings and interiors) lists as basic services there the coordination of the parties involved in construction supervision and the documentation of the construction process. In court the minutes serve as evidence whose weight the court assesses freely (§ 286 ZPO); an objection period after which the content counts as accepted applies only if it was validly agreed (in standard terms only within the limits of § 308 no. 5 BGB), but deviations should in any case be objected to in writing without delay, because between businesses silence can count as consent under the principles of the commercial letter of confirmation (kaufmännisches Bestätigungsschreiben). In Structify, open points from the meeting can be followed up as tickets with photos and deadlines.
The systematic capture and assignment of photos to preserve evidence of condition, progress and defects on site.
Photo documentation (Fotodokumentation) records the condition of the works, progress and defects in images that carry date, time, location and a reference to the building element or service, so that they can be assigned later and used as evidence. It is especially important for works that later construction will cover up; in VOB/B contracts their condition is to be established jointly by client and contractor on request and the result recorded in writing (§ 4 para. 10 VOB/B). If persons are identifiable, the photos are personal data and their processing needs a legal basis under Art. 6 para. 1 GDPR. Structify takes photos directly during the site inspection, assigns them to the report and to defects, and works offline as well.
The German standard for structuring and determining building costs; current version DIN 276:2018-12.
DIN 276 "Kosten im Bauwesen" (building costs) structures the costs of a building project into cost groups 100 (site) to 800 (financing), including 300 for building, structural works and 400 for building, technical systems. It defines six stages of cost determination with increasing accuracy: cost framework (Kostenrahmen), cost estimate (Kostenschätzung), cost calculation (Kostenberechnung), cost quotation (Kostenvoranschlag), cost projection (Kostenanschlag) and final cost determination (Kostenfeststellung). HOAI ties basic services to these stages, for example the cost estimate in LP 2 and the cost calculation in LP 3 (Annex 10 HOAI); for the chargeable costs, § 4 para. 1 HOAI still refers to DIN 276-1:2008-12. Structify calculates the HOAI fee from the chargeable costs, including the § 13 interpolation.
A time schedule that sets start, duration and dependencies of construction activities as target and is updated with actual progress.
A construction schedule (Bauzeitenplan) shows the activities of a construction project with start, duration and dependencies, usually as a bar chart, and is updated during execution so that target and actual progress remain comparable; under Annex 10 HOAI, preparing, updating and monitoring a time schedule is part of construction supervision (LP 8). In VOB contracts, individual deadlines in a construction schedule count as contractual deadlines only if this is expressly agreed in the contract (§ 5 para. 1 VOB/B). The updated schedule also documents the effects of a hindrance, which the contractor must notify in writing without delay (§ 6 para. 1 VOB/B): execution periods are extended only for the reasons listed in § 6 para. 2 VOB/B, additional costs are claimed as damages (§ 6 para. 6 VOB/B) or compensation (§ 642 BGB), and a change order (Nachtrag) under § 2 para. 5 and 6 VOB/B requires changed or additional services. In Structify, site diary entries record the actual course of construction, and change orders are documented traceably.
A continuous record of plant operation with readings, maintenance, faults and measures, kept by the operator as evidence.
An operations log (Betriebstagebuch) continuously documents the operation of a technical installation, such as a district heating network, a heating plant or a ventilation and cooling system: readings and operating parameters, maintenance and inspections, faults and their rectification, and special events. It is part of operator responsibility: the German Ordinance on Industrial Safety and Health requires inspection results to be recorded and retained (§ 14 para. 7 BetrSichV for work equipment, § 17 para. 1 BetrSichV for installations subject to monitoring), and for certain types of installation an operations log is explicitly prescribed, for example for evaporative cooling systems under § 12 of the 42nd BImSchV with a five-year retention period from the last entry. Towards authorities, insurers and clients it serves as evidence of proper operation and maintenance. Structify Operate keeps the operations log digitally.
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