What is additional work in construction and how do you document it properly?

Additional work is one of the biggest “hide costs” in construction and installation projects. Not because the extra work is necessarily wrong, but because it often arises verbally, is done quickly in between other tasks, and only reappears in the records later. Then a discussion suddenly ensues: was this agreed upon, what does it cost, and why isn't it included in the quote?

Good overtime tracking is therefore not bureaucracy. It is a way to keep agreements clear, protect your schedule, and get paid for work that falls outside the original scope.

Additional work: what exactly do we mean by that?

In the construction industry, additional work is extra work that falls outside the original contract, specifications, or quotation and is subsequently commissioned. Examples include extra electrical outlets, a different finish, an additional bulkhead, or relocating pipework because the client wants a different layout after all.

The distinction between is important:

• work that was already within the scope but was underestimated (this is usually not additional work, but a calculation or execution risk), and
• Work that was demonstrably not agreed upon and is added later (that *is* additional work).

That distinction seems simple, but in practice, documents, drawings, verbal instructions on the construction site, and "just do this too" quickly get mixed up. That is why it pays to clearly label additional work and record it separately.

Where does additional work arise in practice?

Additional work rarely arises as a neat, formal change order. It occurs at times when everyone wants to move forward. The contractor wants to move on, the client wants to move on, and the schedule is under pressure. It is precisely then that record-keeping goes wrong.

A few typical sources:

• changes by the client during execution (different materials, extra parts, different placement)
• unforeseen situations on site (wood rot, hidden pipes, poor subsoil)
• additions through coordination (other disciplines that need just a little something, extra openings, extra adjustments)
• external requirements (supervision, environment, sometimes additional regulations)

The more often you experience this, the clearer it becomes: you need a fixed working method that also works when it is busy.

Why a “quick verbal agreement” can cost you money

Legally, there is an important point regarding additional work: you must warn the client in a timely manner that the change will incur extra costs. This is stipulated in Article 7:755 of the Dutch Civil Code. In plain language: if you carry out the work without making it clear beforehand that it will cost more, it can become difficult to demand payment later. Sometimes it is so clear to the client that it will result in extra costs that such a warning leads to less dispute, but gambling on this is risky.

That does not mean that every bit of extra work requires a ten-page contract. A brief written confirmation can go a long way, as long as it is documented:

1. what changes,
2. that it falls outside the original agreement, and
3. what it costs (or how you are going to settle it).

What should be included in a good overtime record?

A work order (paper or digital) is essentially a mini-agreement. The more complete you make it, the less hassle you will have later. In practice, the items below make the difference between “invoice paid” and “disputes after delivery”.

A sentence that prevents a lot of trouble: “Agree on additional work and costs before we carry it out.” That may sometimes feel stiff, but it is actually professional.

A practical workflow that is actually sustainable

Recording extra work only works if it fits the workday. If it becomes an extra administrative task, it gets overlooked. Therefore, keep it concise but consistent: one method of recording, one place to find it, and a clear moment of approval.

In practice, it helps to work with three statuses: flagged, approved, and executed. This allows the office to see what should not yet be invoiced.

After a brief explanation on the construction site, this often works well:

• Brief notification as soon as it smells like extra work
• instant photo and note
• price or rate agreement included
• ask for approval
• only carry out then, unless safety or damage prevents this (in which case document this explicitly).

What you especially want to avoid is “we’ll make a note of it later”. Later it is busy, the details are gone, and the customer remembers it differently.

Following this paragraph is a compact checklist that many small construction companies use to keep the process on track:

• Recognizing the signal: As soon as it falls outside the quotation/specifications, mark it as additional work.
• Instant capture: description, photo, date, involved space/part
• State costs: fixed price or time and materials with rates, including materials
• Bold Arrange agreement: signature or written confirmation before execution
• Bold Update administration: Change status to “approved” and prepare for invoicing

Common mistakes (and how to easily avoid them)

Additional work often goes wrong at the same points. Not because people don't understand, but because the pace of work is high and agreements are scattered across WhatsApp, a scribble on paper, and a remark during a walkthrough.

A few typical blunders:

• Additional work is “hidden” in standard hours, making it unrecognizable on the invoice.
• Material is used but not booked, especially small items.
• There is a photo, but no text accompanying it, so no one knows later what the photo was supposed to prove.
• The agreement was verbal, but cannot be found.
• Additional work is only discussed after delivery, even though emotions often run higher at that time.

A simple preventative measure is to always record additional work as a separate line item and finalize the description on the same day. If you do this systematically, it becomes a habit.

Here is a short list of “quick wins” that take little time but yield big returns:

• separate overtime line per job
• Photo with a short explanation (maximum one sentence)
• Discuss standard rate for time and materials work in advance.
• designated place for approval (email, app, work order)

Digital recording: less searching, faster invoicing

Paper can work, but it gets lost, is submitted late, or is illegible. And loose messages in WhatsApp do not constitute a project file. If you want to keep serious track of overtime, a central register where hours, materials, mileage, and supporting evidence are all together helps.

For small construction and installation companies, that is exactly where Werkbriefje.app This is how it is set up: paper timesheets become digital, with an app for the field and a dashboard for the office. You register per project:

• hours (also travel time, overtime, leave)
• material
• rides and miles (with automatic calculation via Google Maps)
• photos and notes for details and additional work
• a clear moment for submission and approval

The latter is important in practice: it creates a fixed “administrative anchor point”. The employee submits, the office approves, and it is ready for invoice preparation. No more stacks of notes on Friday afternoon.

Additional work and transparency towards your customer

Documenting additional work isn't just about covering your back. Clients often actually appreciate it when you are clear and predictable. Especially if you present it as a choice: “This is possible, this is the cost, what would you like?”

A simple way to do that:

• Show the customer what you have found (a photo helps).
• Explain what the options are (recover now, or later with risks).
• Add costs and ask for approval.

That feels mature and calm. And if a discussion does arise, you have the facts: date, photo, description, hours, and equipment.

What if it concerns unforeseen circumstances?

Sometimes it is not a client request, but a situation that could not be foreseen: hidden defects, altered pipe routing, or construction problems. In a legal sense, this may fall under “cost-increasing circumstances” (Article 7:753 of the Dutch Civil Code), and this does not always correspond directly to additional work commissioned.

In daily practice, that makes little difference to your file: you still want to document what you found, why extra work was necessary, what you did, and what it cost. The conversation with the client becomes easier, too, if you make it visual and factual.

A photo plus a short note such as “wood rot found behind fascia board, section replaced” often makes a world of difference.

Invoicing without surprises starts on the construction site.

Anyone who tries to reconstruct additional work only at the office is playing catch-up. Anyone who records it on the construction site is ahead.

If you want to implement a single improvement, keep it small: agree that everyone immediately documents extra work with a photo and a one-sentence explanation, and that work only resumes after agreement on the price or time-and-materials rate. With a digital work order app, this becomes even easier, because hours, materials , and proof are directly linked to the project and do not get scattered.

Do you work with Werkbriefje.app, then this is in a single flow: registering, explaining, submitting, approving, and preparing for invoicing. That makes additional work not “more administration,” but actually less rework afterwards.