The requirements are in the IBC/IFC. OSHA has requirements, but these depend upon what exactly the nature of the materials are. You say paint, but is it flammable, or is ventilation required for other reasons (such as toxicity)? If the materials are flammable, there are limits on quantities in each room. There will also be requirements for sprinklers and controlling the runoff from these and fire department hoses. There are also requirements for at least two exits, spaced not greater than 1/2 the longest diagonal dimension of the room for hazardous occupancies, up to a maximum egress distance. Some installations also require that doors open to the outside of the building. IBC and OSHA requirements also depend upon whether it is closed container storage or the room is also used for dispensing (transferring materials from one container to another.) See IBC 2012 section 414, for some requirements.
A fire protection engineer or safety engineer will be able to answer these questions with specificity. This is something which requires proper analysis and assessment.
