Writing a defect notice: sample letter and guide for project owners

A formal defect complaint is a written demand for the contractor to rectify an identified construction defect within a specified period. It is the first formal step in asserting defects liability claims after acceptance of building work, and a prerequisite for further rights such as substitute rectification, price reduction or damages. The BSB/IFB Project Owners' Report 2025 documents an average of 31 defects per private construction project — a correctly drafted defect complaint is the decisive step in recovering these costs from the contractor.³

Key points at a glance

• BSB/IFB Report 2025: average of 31 defects per private construction project — correct documentation and setting a deadline are crucial
• Always submit a defect complaint in writing by registered post with acknowledgement of receipt — verbal complaints cannot be proved in a dispute
• Reasonable rectification deadline: generally 14 days, shorter for urgent risks (e.g. water damage)
• After the deadline expires: substitute rectification under § 637 BGB is possible — appoint another contractor and reclaim the costs

When is a formal defect complaint necessary?

Not every defect automatically requires a formal complaint. Timing is decisive: has the work already been accepted or not? This determines which steps you must take.

Defects after acceptance

The classic case: you have accepted the contractor's work, and defects appear some time later. Cracks in plaster, moisture behind tiles, a leaking window. Here, a formal defect complaint is the right approach. Inform the contractor of the defect in writing and set a rectification deadline. Only once this expires can you assert further claims.

Defects before acceptance

Before acceptance, the contractor bears the burden of proof. They must prove that their work is defect-free. An informal defect notice is generally sufficient at this stage. A formal complaint with a deadline is not yet legally required, but can still be useful to document the defect.

Difference from a defect notice

The terms are often confused. A defect notice simply communicates that a defect exists. A formal defect complaint goes further: it demands rectification and sets a specific deadline. Only a complaint with a deadline opens up further rights under § 634 BGB (rectification, substitute rectification, price reduction, damages).¹

Deadlines and formal requirements

Timing matters with defect complaints. Responding too late risks your claims becoming time-barred. The main periods at a glance:

For private project owners, a BGB contract for work with five years of defects liability almost always applies.¹ VOB/B is primarily used for commercial clients.⁴ If VOB/B is agreed in the contract, you must complain about defects within four years. The consumer advice centre points out that reducing the statutory defects liability period through general terms and conditions is impermissible against consumers.⁵

Written form recommended

Written form is not legally mandatory. In theory, you can report a defect verbally. In practice, this is risky because you must prove receipt of the complaint in a dispute. Always use writing, ideally registered post with acknowledgement of receipt or a messenger with delivery confirmation. The Bauherren-Schutzbund (BSB) generally recommends a written complaint by registered post because proof of receipt is often decisive in court.⁶

Setting the right rectification deadline

The additional period must be reasonable. For ordinary construction defects, 14 daysis considered reasonable. For urgent defects (e.g. water ingress), a shorter period may apply. Particularly complex repairs may require longer. Always specify an actual date, not just a period of time.

Calculating periods

The defects liability period begins on the acceptance date. The date in the acceptance record is decisive. With implied acceptance (using the work without formally accepting it), the exact start date is often disputed. This is why formal acceptance with a written record is always the better choice.

Formal defect complaint step by step

The complaint process follows a clear sequence. Following these five steps safeguards your rights and creates a solid basis if the contractor does not respond.

Step 1: document the defect

Before writing, preserve evidence. Photograph the defect from different angles. Note the discovery date, exact location (room, wall, area) and a description of the damage. If possible, measure its extent (crack length, damp patch in centimetres). The more precise your documentation, the harder it is for the contractor to dispute the defect.

Step 2: draft the complaint in writing

The letter must contain three things: a precise description of the defect, a demand for rectification and a specific deadline. Refer to the underlying contract (date and order number where relevant). A sample letter appears later in this article.

Step 3: set a reasonable additional deadline

Generally allow 14 days. State an actual date: “Please rectify the defect by [date].” Rather than “within two weeks”. An actual date leaves no room to argue about when the period began.

Step 4: send by registered post or another provable method

Send the complaint by registered post with acknowledgement of receipt. This lets you prove receipt. Alternatively, have a messenger deliver the letter and confirm its contents and delivery. An email is often insufficient proof in a dispute unless the contractor confirms receipt in writing.

Step 5: monitor the deadline and plan next steps

Note the deadline in your calendar. If the contractor responds and rectifies within the period, check the result carefully. If they do not respond or rectification is defective, further rights under § 634 BGB become available (more in “Your rights after the defect complaint”).

Sample defect complaint letter

The following sample letter contains all necessary elements. Replace the placeholders in square brackets with your details.

[Your name]
[Your street and house number]
[Postcode and town]

To
[Contractor's company]
[Street and house number]
[Postcode and town]

[Town], [date]

Formal defect complaint and demand for rectification
Contract dated [contract date], order number [number] if applicable
Property: [construction project address]

Dear Sir or Madam,

While using/inspecting the work you carried out at the above property, I identified the following defect:

Description of the defect:
[Describe the defect as precisely as possible: location, type, extent and how long it has existed. Example: “In the bathroom (ground floor, right-hand wall), cracks have appeared in the wall tile grouting over a length of approx. 40 cm since [date]. Moisture is also escaping from behind the tiles.”]

Photographic documentation is enclosed with this letter.

I hereby require you to professionally rectify the defect described above under your defects liability obligations pursuant to § 634 no. 1, § 635 BGB by [deadline date, e.g. 15.04.2026] .

Should you fail to rectify within the deadline, I reserve the right to exercise my further rights under § 634 BGB, in particular substitute rectification (§ 637 BGB), price reduction (§ 638 BGB) or damages (§ 636 BGB).

Please acknowledge receipt of this letter and advise me of a date for rectification.

Yours faithfully,

[Your signature]
[Your name]

Enclosures: photographic documentation ([number] photos)

Tip: Adapt the sample letter to your specific case. The more precise the defect description, the fewer grounds the contractor has to challenge it. Blanket wording such as “The work is defective” is insufficient.

Your rights after the defect complaint

If the contractor does not rectify in time or rectification fails, escalation under § 634 BGBapplies. You then have several options, which you can use individually or in combination.¹

Rectification (§ 635 BGB)

This is the normal case and first stage. The contractor has the right and duty to rectify the defect themselves. They are generally allowed two attempts. During this phase, you must provide access to the work.

Substitute rectification (§ 637 BGB)

If the additional deadline has expired without the contractor responding, you may appoint another business to rectify the defect. You can reclaim the costs from the original contractor. Before appointing the replacement, you may request an advance (§ 637 para. 3 BGB). Document costs carefully.

Price reduction (§ 638 BGB)

Instead of rectification, you can reduce the payment for the work. This is suitable if the defect is not serious and you can accept a price reduction. The reduction reflects the loss in value caused by the defect.

Damages (§ 636 BGB)

If the defect causes losses beyond the defect itself (e.g. hotel costs due to uninhabitability, lost rent, consequential damage to other components), you may claim damages. Contractor fault is generally required.

Rescission of the contract

For serious defects, you can withdraw from the contract. This rarely occurs in practice because construction work is difficult to reverse. Price reduction or substitute rectification is generally more practical.

Common mistakes in defect complaints

The complaint itself is not a complicated document. Nevertheless, project owners regularly fail through avoidable errors. We see the following five mistakes particularly often:

1. Verbal instead of written

A phone call or site conversation does not count as proof in a dispute. If the contractor later denies learning of the defect, you have no evidence. Always complain in writing and make receipt provable.

2. No deadline set

Without a specific deadline, you cannot enforce further rights (substitute rectification, price reduction, damages). The deadline is a legal prerequisite for the next escalation stages. Always specify an actual date.

3. Defect description too vague

“The wall is not right” or “Something is wrong in the bathroom” is insufficient. Describe the defect so a third party can understand it: exactly where? What type of damage? Since when? What extent? Attach photos.

4. Complaint too late

Once the defects liability period expires, you can no longer enforce your claims. Regularly check the condition of contractors' work, especially towards the end of the period. Under a BGB contract, you have five years from acceptance. Do not leave it until the final month to discover a defect, leaving no time for proceedings.

5. Paying the final invoice despite a defect

Paying the full invoice despite a defect weakens your negotiating position. Retain a reasonable amount (generally twice the expected rectification costs) and explain to the contractor in writing why you are withholding part of the payment.

When should you involve a solicitor?

Not every construction defect requires a solicitor. In many cases, a well-drafted complaint is enough to prompt rectification. But there are situations where legal support makes sense:

• Damage exceeding 5.000 euros: At this level, legal advice is worthwhile for the financial implications alone.
• Rectification refused: If the contractor fails to respond despite a deadline or expressly refuses rectification, you need legal support for the next steps.
• Disputed cause: If the contractor claims the defect was not caused by their work, independent evidence proceedings (§ 485 ZPO) help. A solicitor can apply for these on your behalf.
• Limitation approaching: If the defects liability period is about to expire and the defect remains, evidence proceedings suspend limitation. A solicitor files the application with the competent court.

Look for a specialist construction and architectural law solicitor. This specialism ensures your solicitor knows the particularities of construction law. An initial consultation generally costs 190 to 250 euros.⁷ DEKRA points out that, when causes are disputed, an independent expert report significantly improves the prospects of successful court enforcement.⁸

Provider comparison: professional review

To avoid construction defects, have the quote reviewed before contracting. Unclear specifications are among the most common causes of subsequent defects disputes because it is difficult to establish afterwards exactly what was owed.²

Compared with subsequent rectification costs (easily several thousand euros) or a legal dispute, an advance quote review offers modestly priced protection.

Frequently asked questions

What must a formal defect complaint contain?

An effective complaint contains three elements: a precise defect description (location, type, extent), a demand for rectification and a specific dated deadline. Refer to the contract and attach photos. The sample letter in this article contains all necessary elements.

How long should the additional period be?

Generally, 14 days is reasonable. For urgent defects (e.g. water ingress), a shorter period may apply. Particularly complex rectification requiring material or appointment planning may warrant a longer period of three to four weeks.

Can I send the complaint by email?

In principle yes, but proving receipt becomes a problem in a dispute. The contractor can claim not to have received the email. Registered post with acknowledgement of receipt is safer. If sending by email, ask for written confirmation of receipt.

What happens if the contractor does not respond?

After the deadline expires, you can assert further rights: substitute rectification (appoint another business and have costs reimbursed), reduction of payment or damages. For larger sums, independent evidence proceedings are advisable beforehand.

Do my claims expire if I do not complain immediately?

Not immediately, but you should act promptly. Under a BGB contract for work, you have five years from acceptance; under a VOB/B contract, four years.¹ You can complain within this period. However, the earlier you report the defect, the easier it is to prove and the more cooperatively most contractors respond.

Further reading: Defects liability in construction: your rights when defects occur · Reviewing a construction contract: what matters · Reviewing a construction quote: the complete guide

Sources

1. Gesetze im Internet, §§ 634, 637, 640 BGB
2. BSB, Bauherren-Schutzbund e.V., guide to construction defects and defects liability
3. Verband Privater Bauherren (VPB) – statistics on construction defects and defects liability claims in private residential construction
4. VOB/B § 13 – defects claims and defects liability periods under VOB contracts
5. Consumer advice centre – defects liability for contractors' services: consumer rights
6. Bauherren-Schutzbund e.V. (BSB) – recommendations on formal defect complaints and proof of receipt
7. German Federal Bar (BRAK) – specialist solicitor regulations: construction and architectural law specialist
8. DEKRA – expert reports for construction defects and preservation of evidence