What is it about?
For houses and plots of land, the building file is often the decisive reality check. It shows what was actually approved – and uncovers discrepancies between the advertised and the approved use. An extended attic, a conservatory, or an extension can only be sold without problems if it is legally compliant with building regulations.
Buyers and their banks increasingly demand building documents because unapproved constructions can lead to demolition orders, value reductions, or financing problems. Anyone who obtains the file early prevents unpleasant surprises shortly before the notary appointment.
Definition and meaning
The building file (Bauakte) is the collection of all documents related to a building, kept by the competent building supervisory authority (in Berlin, by the respective district office (Bezirksamt) or building archives (Bauaktenarchiv)): building applications, building permits, floor plans, sections, elevations, building descriptions, structural analysis, changes of use, and official correspondence.
The scope and completeness vary considerably – depending on the year of construction, district, and archiving history. Not every file contains all documents, and older files may be incomplete.
Why it matters
The building file helps to check whether living space, extensions, loft conversions, garages, parking spaces, and the actual use are legally approved. Discrepancies are a central issue for liability and negotiations.
It is also the basis for accurate living space declarations, for valuations, and for the question of whether later alterations or changes of use are permissible.
The key sections
You should know and check these components:
Building permit and approved use
The legally authoritative document: What was approved and for what use (residential, commercial, ancillary building)?
Building drawings
Floor plans, sections, and elevations. They should correspond with the actual condition and the living space calculation.
Building description and structural analysis
Information on construction method, materials, and structural framework – relevant for alterations and for assessing the condition.
Addenda and changes of use
Later permits, deviations, and conversions. This shows whether extensions have been legalised.
Inspections and conditions
Official acceptances, conditions, or outstanding claims, which can affect the sale.
Example
Building file – what the comparison reveals
A terraced house is advertised 'with a converted attic as a full residential level'. The building file shows a different approved status – a classic case that must be clarified before marketing.
Building permit 1971
Detached house with unconverted attic space
The original approved status does not include a residential attic.
Attic
Approved as a 'storage room', actually converted into living space
The use as living space is not covered by building law without a change of use – this must be disclosed and clarified.
Conservatory
No entry in the file
An unapproved extension can risk a demolition order and should not be included as living space in the exposé without verification.
Living space
Advertised 140 m², provably approved 108 m²
The discrepancy must be clarified, otherwise a reduction in price and damages are threatened.
Who signs? Can a power of attorney be enough?
Responsibility and signature
Owners or expressly authorised representatives apply for file inspection at the competent building supervisory authority or the district's building archives. In Berlin, depending on the location, this is the respective district office.
The application for file inspection is signed by the owner or authorised representative. A new building permit or change of use must be applied for and signed by the building owner (the owner) – a real estate agent cannot substitute this.
Power of attorney and its scope
Yes, with an explicit power of attorney for building file and official matters. Depending on the district, proof of ownership and an identification document are additionally required.
The power of attorney should cover 'file inspection of the building file, request for copies, and communication with the building supervisory authority' for the specific property. For a building application or a change of use, the personal involvement of the owner is required.
Do it yourself: step by step
- 1
Determine the competent district office or building archives based on the property address.
- 2
Prepare proof of ownership and identification.
- 3
Apply in writing for file inspection or copies (partly online in Berlin).
- 4
Compare all plans with the actual condition and the living space calculation.
- 5
Document discrepancies and have them assessed under building law.
Your easy way
Or we take care of it for you
- We submit the application for file inspection with a power of attorney and monitor its processing.
- We sort the file and mark missing or discrepant permits.
- For building law questions, we can arrange an architect or surveyor.
- We will coordinate with you on how discrepancies are handled transparently during the sale.
Important caveats
- Unauthorised constructions can trigger demolition orders and financing problems.
- Old files are sometimes incomplete – missing documents are a negotiation point in themselves.
- The approved use is decisive, not the actual use.
- Stated living areas without file documentation are risky.
Common mistakes
- Advertising a loft or basement conversion as living space without checking the permit.
- Underestimating the long processing time of the building supervisory authority and applying too late.
- Concealing discrepancies instead of dealing with them openly and in a solution-oriented manner.
- Assuming an old extension has become 'legal over time'.
Frequently asked questions
- What if building documents are missing?
- Missing documents are common. They can sometimes be reconstructed (survey, architect) or openly declared as missing. Transparency towards the buyer and bank is important.
- Is an unapproved conversion automatically a problem?
- Not necessarily, but a risk. It may require a change of use and must be disclosed. Concealment can trigger claims for damages.
- Who is allowed to inspect the building file?
- Owners and authorised representatives with proof, and sometimes also persons with a legitimate interest. The specific requirements are determined by the Bezirk.
Note: this article provides general orientation and does not replace legal, tax or financing advice in individual cases. The legal position and authority practice may change. Binding information is provided by a notary, the authority, the bank or a specialist lawyer.