Unfortunately, there isn’t a definitive answer to this, it largely depends on the size and layout of your premises. You need to conduct risk assessments to assess how many people are in your building and if your building is a low/medium or high-risk building. Throughout our experience of talking with thousands of organisations, the general guidance is 1 Fire Warden for every 10 members of staff but this can depend if you are a high/medium or low-risk business. It is then sensible for each Fire Warden to have a deputy in case of absence.