Defective work means that the work does not have the qualities that it should have according to the contract. This occurs either when the work does not have the qualities agreed upon in the contract or, even if there is no specific agreement on this matter, when the content of the contract is taken into consideration, the work lacks the qualities that should exist according to the rule of good faith. Defective work means that the delivered work does not have the qualities that were agreed upon in the contract or that the work should have according to the rule of good faith.
First of all, while concluding the contract of work, the parties make an explicit or implicit agreement on the qualities that the work agreed to be created in the contract will bear. These agreements may relate to either the general characteristics or the special characteristics of the work. General qualities are the qualities that concretely determine the work, such as the shape, size, color, and manner of execution of the work. Special qualities, on the other hand, are the characteristics that more closely define the work determined in terms of its general qualities.
Whether the parties have agreed on a certain general or special characteristic of the work, or which characteristics they have agreed on, is determined by interpreting the contract in the concrete case within the framework of the rule of good faith. It is not only the words used in the contract that are decisive in the interpretation of the contract; the prevailing views in business circles also play a decisive role in the interpretation of the contract.
In the absence of the qualities specifically agreed upon in the contract, the work is defective even if it was created in accordance with the generally accepted rules of the art. In the absence of an attribute that must be present according to the contract, this work is defective even if it is suitable for use to the same degree as the agreed work. The fact that the work is more valuable and more suitable for use does not change this situation. However, in such cases, due to the defectiveness of the work, the conditions for rescission of the contract, reduction of the price or rectification of the defect may not be present, and therefore the owner may have to be content with the work produced. Moreover, in such cases, the exercise of these optional rights may lead to abuse of right.
As to the issue of whether the work of construction agreed upon by the parties in the contract will be deemed defective or not, if one of the characteristics of the work of construction is below the standard stipulated by the generally accepted rules of the art; if the work of construction subject to the contract is constructed in accordance with the express agreement of the parties, but does not have the standard stipulated by the generally accepted rules of the art; in such a case, the existence of a defect cannot be mentioned if the characteristic agreed upon in the contract does not prevent the use of the work in accordance with the purpose stipulated in the contract.
However, if a characteristic agreed upon in the contract, which is contrary to the generally accepted rules of the art, reduces or eliminates the suitability of the work for use in accordance with the purpose of allocation, the question arises whether the work is considered defective or not. As a rule, the contractor shall not be liable for compliance with the provisions agreed upon in the contract regarding the characteristics of the work. However, if the quality that is contrary to the generally accepted rules of the art or below the standard of these rules will reduce or completely eliminate the suitability of the work for use in accordance with the purpose of allocation, in this case, the contractor’s obligation to warn the owner arises in accordance with Article 472/f.3 of the TCO.
If the contractor fails to fulfill this obligation, he shall be liable for the unfitness of the work for use in accordance with the provisions on liability for defective performance regulated under Art. 474 et seq. of the TCO (Art. 472/£.3 and Art. 476 of the TCO). However, if, despite the warning of the contractor, the owner of the contractor, in order to reduce the construction costs or with a similar reasoning, stars in the construction of the work in the quality agreed upon in the contract, the contractor shall not be liable for the resulting defect.

