The purchaser indicates to me that he intends to install his architect's office in the house that I am selling him, do I have to inform myself if he can do so?

Yes, the seller has the obligation to declare to his purchaser, according to his knowledge, all which can affect his immovable property or which would prevent him from using the property in the projected manner. This is why you must indicate to the purchaser the charges which affect the right of ownership or limit the right of use of the dwelling, among others, the municipal zoning regulations concerning the residential and commercial areas. On the other hand, the purchaser, for lack of a precise answer from the seller, must verify the right of use of the dwelling under the applicable zoning regulation.

However, as seller, you can obtain, in the deed, a declaration from the purchaser that he inquired about the destination that he intends to give to the real estate property in particular with the municipal authorities by verifying the applicable zoning regulation.