This tool is designed to help you estimate the pull resistance required of the footing of a shelter to help the shelter survive a storm. Inside the tool (README tab) you will find some tips on how to make shelters more able to resist high winds, and we recommend you read it before using this tool. Armed with this information, you will be able to complete a pull resistance test as outlined in the supporting documents and see if your footings are able to resist the load. This tool calculates the load on the roof. It is somewhat speculative in that it assumes the load can be distributed across several of the columns and ignores the fact that the roof fixings might fail first. However, it does give an idea of the kind of loads that might happen at various wind speeds. It is important to understand that the total loading on the whole building might not be evenly distributed across the columns and the whole method is extremely approximate.