Foundations are often an expensive pitfall for the unwary but with sufficient investigation of the site beforehand, there should be no need for cost escalations due to "difficult ground conditions".
The most basic form of investigation is the "trial pit" survey. Click here to download our guidance notes.
There are many types of structural solutions available, and the selection and design of the appropriate one depends on the collection of the right data, expertise and a bit of local knowledge and experience.