The main design of the building's construction structural part is intended for cost estimation and organizing the construction tender. The main design does not assume the level of detail characteristic of the working/project design, but the clarifications made in the working/project design should not change the cost calculation derived from the construction cost estimate. It is not advisable to build based solely on the main design because this stage of the project is not prepared with sufficient detail for construction. Generally, liability insurance does not apply to objects constructed based on the main design stage.