Cross-Checking BBR Against Reality: Photo, Map, Permits

BBR (the Buildings & Dwellings Register) is the most used and the most overlooked dataset in a property valuation. Used, because everyone starts there: areas, use, year of construction, condition. Overlooked, because few people remember that the entries are reported by the owner and are not checked systematically. The municipality updates the register in connection with building cases and spot checks, but there is no ongoing physical verification of whether the 142 m² in the register actually stand on the site. That does not make BBR useless — it means that a figure from BBR is a claim until you have confirmed it elsewhere.

A cross-check is therefore not an extra layer of diligence you can add if there is time for it. It is the difference between an area you can capitalise on and an area you are guessing at. For a valuer, an engineer, a building consultant or an insurance assessor, the entire calculation sits on top of those figures — and an undiscovered discrepancy feeds straight into the conclusion. Here is the method that surfaces the discrepancies before they become expensive.

Why BBR cannot stand alone

BBR’s weakness is structural, not incidental. The register is built on owner reporting, and the owner rarely has an incentive to keep it updated after a conversion — or has simply forgotten. Extensions, outbuildings absorbed into living space, demolished carports, converted loft and basement areas: all of it lives on in the register in a state that can be years away from reality. Add to that plain reporting errors and inconsistent practice in how areas are measured and assigned to the individual buildings.

Anyone who builds a conclusion on a single BBR extract inherits all these errors unfiltered. We have covered what the register contains, and where it typically fails, in BBR data in property development: what they show — and where they get it wrong and in a more fundamental walk-through of BBR as a data source: areas, use codes and verification. The point here is operational: every BBR figure must be met with at least one independent source before it enters a valuation.

Rule of thumb: No BBR entry should enter a conclusion without at least one independent reference point — the cadastre, an aerial photo, a building case or the Land Registry. If the figure stands alone, it is a hypothesis, not a data point.

Step 1: BBR against the cadastre

The first and cheapest cross-check is against the cadastre (matriklen). The cadastre tells you where the site’s boundaries lie and how large the plot area is — and those are two things BBR does not determine. Overlay the buildings’ registered position on the cadastral map and see whether the geometry holds together: does the building sit within the boundaries, and does the footprint match what the plot can accommodate within the permitted plot ratio?

Concrete discrepancies a BBR vs cadastre check typically reveals:

• Buildings that cross the boundary or sit on the neighbouring parcel — often a sign of an old boundary shift or a subdivision that was never followed up in BBR.
• No coherence between plot area and footprint — if the footprint implies a plot ratio the site cannot carry, then either the area or the use is registered incorrectly.
• Several BFE numbers on what is in practice one property, or the reverse — relevant for both ownership and taxation.

The cadastral area is also the key that ties BBR to planning conditions: the plot ratio is calculated from the plot area, and without a verified plot area you cannot assess whether the property is fully utilised, under-utilised or already over-utilised relative to the local plan.

Step 2: BBR against aerial photos

A BBR vs aerial photo check is the fastest reality check there is. Orthophotos show what actually stands on the site right now — and with historical aerial photo series you can see when the building footprint changed. It is especially powerful for catching what the owner forgot to report.

Hold the register up against the image and look for:

• Buildings in the photo that are not in BBR — an extension, a garage, an annexe. Area that may have been built legally but never registered, or that lacks a building permit.
• Buildings in BBR that are not in the photo — demolished, but never de-registered. A “ghost area” that pushes the valuation too high.
• Roof surfaces and footprints that do not match the registered footprint — an indication that the area record was never updated after a conversion.

Aerial photos do not settle areas down to the square metre, and they cannot see inside the building. But they tell you immediately whether there is any coherence at all between the register and reality — and where to dig further. Note that the footprint in a photo is something other than the area concepts BBR works with; we cover the difference between footprint, living area and heated area in BBR areas explained: living area, heated area and footprint, and that difference matters when you translate a roof footprint into a usable gross floor area.

Step 3: BBR against the permit archive

Where the aerial photo shows what stands there, the permit archive tells you whether it is allowed to stand there. A permit archive vs BBR check is what separates a lawful property from one carrying a hidden legalisation risk. The municipality’s building case archive contains the permits, occupancy permits and dispensations behind the building — and it is here you find out whether the absorbed basement area, the conservatory or the additional dwelling is in fact approved.

This is especially critical for engineers and building consultants, because an unauthorised structure is not only a legal problem — it is often also a technical one. A loft taken into use for residential purposes without a building case is rarely documented for fire requirements, escape routes, rescue openings or load-bearing structures that the building code requires. Where the permit is missing, the documentation is usually missing too.

Three questions to put to the archive:

1. Is there a building permit for the area BBR registers? If BBR shows a larger area than the most recent case covers, there is either an unregistered change or an unfinished case.
2. Is there an occupancy permit? A building case without a final occupancy permit may mean the building was formally never lawfully taken into use.
3. Does the use rest on a dispensation? Dispensations are tied to conditions and may in some cases be time-limited — verify the terms, not just that the dispensation exists.

Find discrepancies here, and you have moved a problem from “discovered after completion” to “priced before the deal”.

Step 4: BBR against the Land Registry

The final cross-check closes the circle between the physical building and the rights that rest on it. The Land Registry (tingbogen) is the authoritative source for title, encumbrances and easements — and its sections can hold burdens that directly limit what the building may be used for, regardless of what BBR says about the use.

Look for easements concerning the extent of building, use, sight-line areas, road and utility rights, or conservation provisions. A registered building line or a covenant on maximum building can render a registered expansion potential unusable — and a conservation easement can bind a building that BBR otherwise presents as freely usable. Also reconcile the title with what you found in the cadastre: that the ownership and the property boundaries actually match.

The cross-check against the Land Registry, the cadastre and the permit archive is the core of a proper preliminary investigation — and it features as a fixed item in the checklist from cadastre to project proposal in a site due diligence, where the four sources are brought together into a single picture.

How Arcili automates the manual exercise

The cross-check is not hard — it is time-consuming. Four sources, four systems, four tabs, and a manual collation that easily takes half a day per property if the archive has to be ordered and aerial photos pulled separately. That is precisely the friction that means the cross-check is, in practice, often skipped — right up until a discrepancy surfaces at the worst possible moment.

In Arcili, the same public sources sit together in one place. The BBR tab under Ejendomme (Properties) shows building data side by side with the cadastre, planning conditions, the Land Registry and the surrounding area, so discrepancies between the register and the other registers become visible immediately instead of having to be stitched together by hand. You still make the professional judgement — you just don’t spend the hours pulling and collating data that already sits in public registers. It does not remove the need for a critical eye. It removes the excuse for letting BBR stand alone.

See what the cross-check looks like in practice in Arcili, or book a walkthrough and try it on a specific property.