"COS 0,14 + 1 er étage". What the heck does that mean.... I know it has something to do with how big a house we could build. But any more than that I don't have a clue!
Buying land in Switzerland - experiences
Buying land (property) in Switzerland
COS is French for coefficient of land use or something like that.
In your case as explained above by Patxi with a first floor over (and not more) - I imagine you could have another excavated underground floor as per usual in CH, for garage, storage, heating, cellar, utility, etc.
Very wise to check this very carefully and make absolutely sure what you could or couldn't do.
I'm used to work with BZ (Baumassenziffer), but this should be similar. When in doubt, ask the seller.
In this case, it's not given what exactly this COS is (OP should maybe past the whole text). But considering that it is specifically written: COS 0.14 + 1re etage, it leads to believe this coeficient is actually refering to the brutto area of the ground floor only, and allows for an extra 1st floor.
The seller is forced to inform the potencial buyer on the information he/she gives about the land. The seller has to give enough information about this COS when asked for. The Bauamt only needs to be contacted if you suspect you are being fooled or need extra info before signing the contract.
I wouldn't go storming the Bauamt for this. They are rude and useless on the best of days, so I wouldn't jump into the lion's den to ask if it's the right way to Rome.
*Is it obvious been having bad experiences with the Bauamt?*
Don't know. All the agencies I used while looking for a new home were very professional and gave me all the information I needed even before I asked for it, including summaries of what was allowed to be changed on the houses.
The Bauamt of the areas I work with are useless pricks.
I guess we both had met the best and worse side of each.
Again, it would be more useful if OP would post the whole text.
The sellers and their agents - of the property I bought, and of several I've since considered buying - offered little information as to the restrictions surrounding the property. At least in my experience, it seems to be up to the buyer to determine what he may, or may not, do with the property, and you may have little recourse if it turns out that the property is not buildable as you had been told.
As a buyer, I've learned the hard way* that I have to chase down all relevant Gemeinde, Bezirk, and cantonal authorities who have sway over the property. That may include the Amt für Raumentwicklung, Landwirtshaftamt , Forstamt, or Wasseramt - as well as the Gemeinde and cantonal Bauamts.
I've had to walk away from several purchases because I could not hunt down the relevant authority/official quickly enough.
Also be aware that in addition to the Ausnutzungsziffer on your property, there may also be one for the neighborhood as a whole. It's possible that although you have plenty of building room allowed by your ratio, someone in the neighborhood has already been granted an exception to his ratio - and in essence used up yours, because his exception counts against the Quartier maximum.
Absolute caveat emptor - and selber schuld if you don't do due diligence yourself.
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* When I bought my current home I had planned to build a Wintergarten - some homes of the same design the Quartier had originally been built with Wintergartens, and my property had more than twice the land, and therefore Ausnutzungsziffer, they did. The sellers, agent, and Bauamt assured me that a Wintergarten would be no problem.
I also asked if the house was part of an 'association', and were there any 'building or design rules' governing what I could or could not do to my house. I was told no.
Boy, was was naive.
Turned out the house is part of a Quartier, and there is a water-tight Gestaltungs plan restricting every aspect of building, renovation, facade and garden. The sellers did not lie, you see, as I asked using the wrong terms. It's a 'Quartier', not an association, and a 'Gestaltungsplan', not building or design rules. Never expect a seller, agent or official to volunteer information, and be sure you ask the right question using the exact terms if you want a definitive answer.
Not being a total idiot, though, I had asked at the Gemeinde Bauamt if building a Wintergarten would be possible - and was told 'no problem'. But it turns out I had asked at the wrong Bauamt. The Gestaltungsplan was governed by the cantonal Bauamt, not the Gemeinde. Who'd a thunk it?
So here I am, without my Wintergarten.
Eyes wide open, and take nothing on trust. Veryify everything, and then ask what else you should be asking.
But the OP wants to know what the little note means. I would advise to find out first from the seller, and when getting serious then bothering the Bauamt to confirm.
No idea how it's called in French.
Never, ever take anyone's word for it.. rule of thumb for me when it comes to property buying in CH: get all answers in writing and do your homework so you know the right questions to ask.
Agree totally with Phil as I have always asked questions to cover anything I might have missed:
Are there any other rules/regulations I need to know in order to build, buy, extend or even put a fence up etc. Have you any information/forms that I need to read in order to prepare myself when buying/extending this property?
If I have had a meeting with the building authorities in the Gemeinde, I have always followed it up with an e-mail to said person confirming what she/he has told me and ask them if I have understood everything correctly so far.
Funny how they have always answered my e-mails be giving me more info to read