ᐅ 130 m² house, one and a half stories, ratio of usable area to living space

Hello everyone,
we have now agreed on the general design of our house and have already created a floor plan. However, the question arises: how big is the house actually?
One home builder talks about usable floor area, another about living area or built-up area.

In our floor plan, the external dimensions are 9.63 x 9.825 meters (32 x 32 feet). I have subtracted all walls from this floor plan and added that to the living area, so it should be about 130 m² (1,399 sq ft). Is that correct? It seems a bit large to me.

Could someone clarify this for me? It is important to us to have a rough floor plan so that we can also calculate a price.

Thank you

I wouldn’t want to calculate or specify anything based on this sketch, as the dimensions are not realistic if you have average expectations for living space. Much will still change. For example, the staircase looks more like a children’s slide than one for a single-family home.

Since you have already compared your living preferences in model homes or similar, and you roughly want around 130 sqm (1400 sq ft), the architects and home builders can calculate the cost based on their typical or standardized house models (there’s not much else to identify from the sketch, apart from maybe a roughly planned two-story townhouse with a hip roof?). It’s basically the same: 2 children’s rooms, master bedroom, office, bathroom, guest toilet, living room, dining room and kitchen plus utility room and hallways. The average cost is about €1800 (around $1900) per sqm (sq ft) for a good standard, higher standards cost more, plus additional building costs, landscaping, electrical installation, and garage/carport.
If you want 10 sqm (110 sq ft) more or some modifications, that can easily be calculated afterwards.

I estimate it will be around 150-160 sqm (1,615-1,722 sq ft), depending on the roof slope.
With two full floors, it would be 180 sqm (1,938 sq ft).

A 1.5-story house with these exterior dimensions roughly has 120-130 sqm (1,290-1,400 sq ft) of living area.

And to complete the picture, I estimate about 140 square meters (1507 square feet) of living space.

Important for me: what exactly is included in the usable floor area? Is it just the actual floor space inside the rooms? The walls would logically count as additional space (built-up area), right?