Cover to reinforcement bars is identified in a different manner by the design engineers around the world. Some used this dimension as the distance between the concrete surface and the face of the reinforcement bar. However, some use this differently. For example, consider a beam. When we say cover, some say it to link, some say it to main reinforcements.
However, it should be cove to any reinforcement. Whether it is a link or main reinforcement or transverse reinforcement, we need to have the cover considering the exposure condition and fire rating.
Fire rating is decided based on the type of building and its requirements. When there is a higher risk of having a fire we may select a higher value, and also we need to consider the time required to evacuate the building.
When it comes to exposure conditions, it is considered the environment that the structure is constructed. Is it in the water, is it frequently wet or any other way of exposure to weather is considered when deciding the cover to the reinforcement. BS 8110 has defined these exposure conditions and have categorized as mild, moderate, severe, very severe, most severe and abrasive. Once we select the exposure condition that our structures fall, cover to the reinforcement can be selected from table 3.3 of BS 8110 Part 01.
Generally, we consider exposure condition and fire rating when selecting the cover to the reinforcements. The highest value of cover given by both methods is selected as the cover to the reinforcements.
The following table is referred for the above purpose.