To design a risk map for a building project, the following steps can be taken:

1. Identify the Risks: The first step is to identify the potential risks that could arise during the building project. These could include risks related to safety, financial risks, legal risks, environmental risks, and so on.
2. Assess the Risks: Once the risks have been identified, it is important to assess their likelihood of occurring and the potential impact they could have on the project. This can be done by assigning a probability and severity rating to each risk.
3. Prioritize the Risks: The risks should then be prioritized based on their severity and likelihood. The most severe and likely risks should be given the highest priority.
4. Create a Risk Map: The risk map is a graphical representation of the prioritized risks. It is typically divided into four quadrants: High Probability/High Impact, High Probability/Low Impact, Low Probability/High Impact, and Low Probability/Low Impact. Each risk is placed on the map based on its probability and impact rating.
5. Develop Risk Mitigation Strategies: Once the risk map has been created, it is important to develop strategies to mitigate each identified risk. This could involve taking steps to reduce the likelihood of the risk occurring, or to minimize the impact if the risk does occur.
6. Monitor and Review: Finally, it is important to regularly monitor and review the risk map to ensure that the risks are being managed effectively, and to make adjustments as necessary.

Overall, a well-designed risk map can help to identify potential risks, prioritize them, and develop strategies to mitigate them, thus minimizing the impact of risks on the building project.