Possible cost overrun

What is a cost estimate?

A cost estimate is a kind of attack on the wallet.

On the topic:
"unfortunately" having built with an architect might be a premature judgment. We know the feeling when the architect blows the budget. That is initially not nice. The main cost drivers proved to be ground movement, development, and foundations. The craftsmen consistently stayed within the scope of what was offered. The other significant additional costs resulted from our many detailed decisions, which were almost always made according to the principle "wow, that is brilliant, let's treat ourselves to that too." It is important that everything remains feasible.
You don’t get a price guarantee with an individual house. Price guarantees exist for industrial goods or when the supplier is certain of their margin.