construction Ausnützungsziffer [Utilisation factor] question

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1
Hi All,

In building properties in CH there is a utility ratio that defines how much of a building can be built. Part of that I understood basement, corridors, balconies are not part of building area calculation. However I am not clear on the attic part. Is attic part of utilisation or not?! have you had any experiences? would you please share with me what is expected?

Thanks,

2
If you can live or work in the attic it is part of it, otherwise it is not. For more details see the building codes of your canton.

3
Generally speaking it has to be a livable space, i.e. heated, lighted, etc. If unfinished and storage space no; if heated, insulated and electrics, yes.

Finished or renovated basements can also be included if livable, as above, it is not defined by the name or placement.

4
Another twist on Ausnützungsziffer, in case it might apply to you.

We were surprised to learn that two calculations applied to our house: The Ausnutzungsziffer specific to our property ( my own % m2 land to m2/m3 house AND an Ausnützungsziffer for our Quartier of 18 houses as a whole. So if one home owner had somehow sometime ago finagled an add-on in excess of their own property Ausnützungsziffer, other property owners might find that they are not able to build to the limit of their allowance, as the Quartier limit has been reached.

Which is why we don’t have the Wintergarden we had planned to build...

If your property has any sort of communal aspect to it, ask if there are any additional calculations that apply to your property.

5
In our last house, which was bungalow style, the top floor did not count. It was about 140 square meters of floor space with 2 roof windows. There was no central heating. The roof was sloped so the usable space was less than 140 square meters but there was still plenty of room to use. Access was with a flight of stairs.

I have seen people add wintergardens with fireplaces. As that isn't central heating, the wintergarden doesn't count as living space.

I think the rules vary by canton.