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What's actually on a property record — and which numbers should I look at?

The official property record is the property's registered profile. Here are the fields that get misread most often, and how to read them without drawing the wrong conclusion.

What the record is — and isn't

Most countries keep some kind of public register of buildings and homes. In the UK this shows up as Land Registry data and an Energy Performance Certificate; in the US it's the county assessor's records. Wherever it lives, it's usually the owner's responsibility to see that the information about the property is correct and up to date.

The property record is the printout: the property's registered profile with area, year built, external wall material, roof covering, heating system, water supply, drainage, and the number of rooms, toilets and bathrooms.

The important thing to understand is that a register like this describes what is registered. If an extension was built without being reported, it isn't in there. If the heating was replaced ten years ago, an old boiler might still be listed. The record isn't an inspection — it's an entry that someone typed in at some point, which no one has necessarily had cause to check since.

The three areas that get mixed up

Living area. The total area registered for habitation. Usually measured externally — to the outside face of the external walls — with internal partition walls counted in. This is the figure that listings and price-per-square-metre calculations are normally built on.

Footprint. The house's outline on the plot, seen from above. A house with two full storeys and 160 m² of total living area typically has a footprint of around 80 m², because the two storeys sit on top of each other. Compare your own floor measurement from both storeys against that figure, and it looks as if half the house is missing.

Total building area. Every floor's area added together, often including areas that aren't living space. It's typically larger than the living area as a result, and the difference between the two is often precisely a basement or an integrated garage.

On top of that come separate fields for basement area, finished attic, conservatory, garage, carport, outbuilding and covered area. As a rule, basement, garage, carport, outbuilding and conservatory are not part of the living area — they're counted separately, and that is exactly what lets a listing and a property record show wildly different numbers for the same house.

Why your own measurement is always smaller

Because a registered living area is normally measured externally, while you measure internally, wall to wall. The difference is the walls, and it's bigger than most people expect.

The rule of thumb: the external walls take up roughly the wall thickness times the house's perimeter. A house measuring 8 × 12 m has a perimeter of 40 m and a registered area of 96 m². With 35 cm external walls: 40 × 0.35 = 14 m² of wall — slightly less in reality, because the rule counts the corners twice, so the true figure is 13.5 m². Left inside the walls: 96 − 13.5 = 82.5 m². Partition walls typically take another 2-4 m² on top, so the floor you can actually walk on is around 79 m². No one has miscounted anything.

Put as a percentage, that's 17 m² out of 96, or roughly 18%. On an ordinary house, the loss typically runs between 15 and 20%, and it's biggest in small houses and smallest in large ones — because the walls follow the house's perimeter, while the area grows faster than the perimeter does. That's why you can't apply one percentage to every house.

You can measure the wall thickness yourself at a window reveal: from the internal wall face to the external one. Do it at three different windows on different sides of the house; it's rarely the same all the way round.

The fields that go out of date most often

When you read a property record — on your own home, or one you're considering buying — these are the fields that most often no longer match reality:

• Heating system. An oil boiler that quietly became a heat pump or district heating, with no one reporting it.
• Finished attic. Either it's listed as finished when it isn't, or rooms were fitted out up there that were never registered.
• Number of toilets and bathrooms. An extra bathroom in the basement is a classic.
• Garage and outbuilding. Demolished, rebuilt or newly built without being reported.
• Living area after an extension. The most expensive one to overlook, because it can hinge on whether there's actually an approval for the extension at all.

If you find something that doesn't match, it's normally the owner's responsibility to get it corrected, and the correction goes through the authority that maintains the record. Some fields the owner can update themselves; others need processing, and a few assume there's a building application behind them. What applies to your particular field changes over time — ask the authority rather than guess.

How to read the record in ten minutes

1. Find the living area and note exactly what the field is called. The field name is half the information.
2. Note the other area fields separately — basement, attic, conservatory, garage, carport.
3. Try to hit the listing's headline figure by adding the fields together one at a time. If living area plus basement lands exactly on the listing's number, you know what the listing has done.
4. Work out the walls with the rule of thumb — wall thickness times perimeter — and see whether your own floor measurement matches the living area.
5. Go through the fields that date quickly — heating, bathrooms, attic, outbuildings — and see whether they match what you can see with your own eyes.

What you're left with is a list of discrepancies that can't be explained by the measuring method. That list is worth taking to the agent or the authority. Everything else is noise.

What the record doesn't tell you

A building register says nothing about whether a wall is load-bearing. That question can only be answered by a chartered surveyor or an engineer who has seen the structure on site, and that holds true no matter how detailed the record is.

The record also says nothing about the home's condition, whether there's damp, whether the insulation works, or whether an area is legally fitted out even if it's listed as registered. Registration and approval are two different things, and mixing them up is more expensive than every area mix-up put together.

Your own basis alongside the record

The strongest thing you can have in hand when you talk to an agent or an authority is your own measured numbers and a drawing to point to. Not as counter-evidence against the record — the two measure differently — but as something concrete to explain the difference from.

HouseSense produces that basis: scan the home with the iPhone's LiDAR, or draw it on graph paper with your finger. You get a measured floor plan with area per room and in total, measured internally wall to wall, and you can send it on as a PDF.

HouseSense doesn't decide what counts as living area in a public register, and it can't say whether a registration is correct. The authority does that. But the app gives you the numbers and the drawing, so the conversation ends up being about something measured instead of a feeling.