ᐅ Bringing Living and Usable Area to a Common Standard for Comparison

Hello and good morning,

I hope my question is appropriate here.
It concerns a semi-detached house on a single plot, where each unit has different living and usable floor areas.
Both sizes of the respective halves should be made comparable.

We have the following sizes:

Half 1:
Living area: 100 m² (1,076 sq ft)
Usable area: 30 m² (323 sq ft)

Half 2:
Living area: 80 m² (861 sq ft)
Usable area: 80 m² (861 sq ft)

Now I am trying to find a way to put the values on a “common denominator” so they can be compared. What I am looking for is an “official” conversion factor to make usable area comparable to living area, if such a thing exists. If not, the question is how these areas are practically compared.
Usable area logically counts less, since it is not heated or suitable for living.
I have already found the NFA (Net Floor Area) factor, but that only describes the ratio between usable area and gross floor area.

Simply adding both values together, in my opinion, also doesn’t make sense because of their different weighting.

Assuming the factor were around 0.7 (I am looking for something solid and official, not just a rough approximation),

I could calculate half 1 like this, for example:
30 m² usable area * 0.7 = 21 m² (fictitious living area)
100 m² (living area) + 21 m² (fictitious living area) = 121 comparative value

and half 2 like this:
80 m² usable area * 0.7 = 56 m² (fictitious living area)
80 m² (living area) + 56 m² (fictitious living area) = 136 comparative value

Could someone please help me and let me know if or how such size specifications with different weightings can be put on a comparable basis?

Joachim_84 schrieb:

If such a thing even exists. If not, the question is how these areas can be practically compared with each other.

They can’t.
You have to individually decide for each property what the usable area is worth to YOU. Is it a dark basement room without windows, or perhaps an attic that has been converted, but is not officially classified as living space, with proper lighting?

nordanney schrieb:

You need to decide individually for each property,

However, the original poster does not seem to want to compare two offered semi-detached houses, but rather to find a fair basis to share resident, street cleaning, or other fees with their neighbor. The issue seems to be that when comparing total areas, their share would be 13:16, but when comparing living areas, it would be 10:8 – both differing from an equal half, only that sometimes their side and sometimes the neighbor’s side weighs heavier. Even if the living area were weighted twice as much as the utility area, the ratio would be 23:24, and the neighbor, despite having a smaller living area, would be the larger payer—which understandably could cause the neighbor to feel disadvantaged.

What areas are actually being discussed? With 30 square meters (323 square feet), it can hardly be a leftover garden area of the plot, so is the “utility area” referring to storage rooms and similar spaces?

Joachim_84 schrieb:

In my opinion, simply adding both values also doesn’t make sense because of the different weightings.

Tell us what this is about exactly. For cubic meters of sweeping, the garden would also need to be considered—that is, how would the plot shares be if the property boundary were along the party wall? Do you have shared property ownership, or is he your tenant?

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11ant schrieb:

to fairly share costs such as local taxes, street cleaning, or other fees with their neighbor.

And does that require land areas? If it is located on one plot, there will only be one owner. What other fees are you thinking of? Street cleaning fees = length of the property section per house ==> easy to split. Local taxes for what purpose?

Thank you for your responses.

nordanney schrieb:

If it is located on one plot of land, there will only be one owner.

Not exactly. In this case, there are two people listed jointly on a loan agreement and both are registered together in the land register. They are not married but related.

11ant schrieb:

...the ratio would be 23:24, and his neighbor would be the bigger payer despite having less living space – which understandably has the potential for the neighbor to feel disadvantaged.

Exactly. It’s about this weighting and avoiding any unfairness. The goal is to fairly balance the financial differences so that no one has a disadvantage or advantage and, in the end, everything is divided “equally.” The latter may mean paying more.

11ant schrieb:

Which areas are we actually talking about?

The areas refer to covered, enclosed spaces such as a basement under the living area and a solid outbuilding from this example. The garden is completely excluded, as it is used jointly.

Half 1: living area 100 m² (1076 sq ft), usable area 30 m² (323 sq ft) (basement)
Half 2: living area 80 m² (861 sq ft), usable area 80 m² (861 sq ft) (solid outbuilding)

I’m trying not to make a complicated formula and am not entirely sure how to approach this. Therefore, my question is how to calculate this in the best way and/or which method is fair, transparent, and ideally official.

Joachim_84 schrieb:

It’s about this weighting and unfair advantage. The goal is to fairly balance out the financial differences.

Understood.
Then please specify exactly which costs you mean. I think you will get more suitable answers that way. Your conversion method won’t work at all.