Preparing delay and concern notices under the VOB/B

A delay notice (Behinderungsanzeige) or a notice of concerns (Bedenkenanzeige) records in writing what obstructs the work or what the site manager has technical concerns about. It is only as good as the records behind it. An AI can gather those records and draft a text that names the source for every statement. Whether notice is given, what it says and when it goes out is decided by the site manager, and where in doubt by a lawyer.

What the two notices are for

What follows are general references to the VOB/B (German standard contract terms for construction works) in the 2016 edition. I quote the unofficial text published by the federal building ministry. The edition was officially announced in the Federal Gazette (Bundesanzeiger, BAnz AT 19.01.2016 B3, corrected in BAnz AT 01.04.2016 B1). According to the federal construction information service (Fachinformation Bundesbau), Part B continues to apply unchanged in its 2016 edition. A draft of a revised VOB/B has existed since late 2020, but in my research (as at November 2026) it is not in force. The new VOB/A announced in August 2026 also concerns only sections 2 and 3 of Part A. Whether the VOB/B has been agreed in your contract, and in which version, is stated in the contract.

The delay notice is regulated by section 6(1) VOB/B. If the contractor believes it is obstructed in the proper execution of the work, it must notify the client of this in writing without delay. If it omits the notice, it can have the obstructing circumstances taken into account only if the client obviously knew of the fact and its obstructing effect. Whether an email is enough for the written form or a signed letter is needed is not covered in this article. Your lawyer clarifies that.

Further consequences attach to an obstruction. Under section 6(2), execution periods are extended where the obstruction is caused, for example, by a circumstance from the client’s sphere of risk. Under section 6(3), the contractor must do everything that can reasonably be expected of it to keep the work going. Once the obstructing circumstances end, it must resume work without delay and inform the client. Where a party is responsible for the obstructing circumstances, the other party can claim compensation under section 6(6) for the damage proven, but for lost profit only in cases of intent or gross negligence.

Otherwise the contractor’s claim to reasonable compensation under section 642 of the German Civil Code (BGB) remains unaffected, provided the notice is given or the obviousness described in the clause exists. Section 642 BGB gives the contractor reasonable compensation if the client falls into default of acceptance by failing to do something required for the work.

The notice of concerns is regulated by section 4(3) VOB/B. If the contractor has concerns about the intended method of execution (also with regard to safeguarding against accident hazards), about the quality of materials or components supplied by the client, or about the work of other contractors, it must notify the client of them in writing without delay, if possible before the work starts. The client nevertheless remains responsible for its specifications, instructions and supplies.

Under section 13(3) VOB/B, the contractor is not liable for a defect that traces back to the specification, the client’s instructions, materials or components supplied or prescribed by the client, or the condition of the preliminary work of another contractor, if it has given the notice under section 4(3). The BGB also attaches consequences: if, before acceptance, the work is destroyed, deteriorates or becomes impossible to carry out because of a defect in material supplied by the client or an instruction from the client, the contractor can, under the conditions of section 645 BGB, claim the part of the remuneration corresponding to the work done.

The notice therefore serves as proof that you informed the client in good time. How the rules take effect in a particular case is for your lawyer to clarify. This article is not legal advice.

What is gathered

A notice is only as reliable as its statements can be evidenced. You need four things for that:

• Site diary: what was built on which day, who was there, what could not proceed, and since when.
• Photos with date and location: they record the condition that the site diary describes.
• Correspondence: drawings, approvals, instructions, queries, emails and meeting minutes showing what you told whom and when.
• The contract with its programme: which periods are agreed and which preliminary work was promised.

How to record the site diary and defects on site by voice note and photo is described in Site diary and defects: record them by voice and photo. Anyone who enters things there straight away already has the basis for the notice on the same day.

What the AI makes of it

The AI searches your files for the incident: site diary entries for the days concerned, the related photos, emails and minutes. From them it drafts a text with a fixed structure, for example facts, period of the obstruction, work affected, who is responsible, earlier notifications and a request for a reply. Behind every statement stands the source, such as “site diary 14 March, entry 2” or “email of 12 March, 09:12”. Why this source reference is needed is explained in Why AI answers need a source reference. What the AI cannot find in your documents it marks as a gap, and it adds nothing of its own.

An example with invented data: the shell construction is finished, but the building services cannot start because the drawings for the cable routing are missing. The AI finds three site diary entries on the idle days, two photos of the empty shaft and the email with which the site manager requested the drawings. From these a draft is produced that cites those three sources. The site manager sees at once what is evidenced and what has to be added personally.

Figures in the text, such as days of delay, are calculated by a fixed program or a spreadsheet, not by the language model. The draft is deliberately sober. It describes facts and sources and does not assess fault. Especially where concerns relate to the work of other contractors or to the client’s specifications, the tone stays factual, because the notice may later be read by third parties, such as your lawyer. Keep a copy of the version sent, together with proof of dispatch, in the project files.

What stays with the site manager

The site manager checks every statement against the original. The site manager decides whether it is an obstruction or a matter of concerns, whether a notice is needed and what the text demands. The site manager signs and sends. Where unsure, the site manager asks the lawyer before the text goes out. The AI takes over no legal assessments, periods or demands. The following graphic shows, as general orientation, which of the two rules is engaged in each case.

Time matters. Both rules speak of “without delay”. Anyone who reconstructs things from memory after weeks has less to rely on than someone who could make an entry on the day of the incident. How a court would weigh this in a particular case is for your lawyer to clarify.

The documents contain names, prices and dates. They can be processed on a platform that can be operated in line with the GDPR, not in a consumer chat service. Which contract you need with the provider is described in Data processing agreements for AI services: what to check. Your data protection officer clarifies that.

What you can do now

1. Check in your contracts whether the VOB/B has been agreed and in which version.
2. Decide who in your firm signs notices and who sends them.
3. Enter obstructions in the site diary on the same day, with date, cause and photo.
4. Create a template with the headings facts, period, work affected, earlier notifications and sources, and have your lawyer look it over once.