Hi @rebecca telfer. I recently had to deal with the same / similar question. What I found is by no means the definitive answer however enough to satisfy us that we were in the right place.
The upshot: Based on everything looked at, there is no legal requirement to provide facilities for smoking or vaping. Doing so is a business decision and must be done in a manner that protects non-smokers from second-hand smoke. Considerations are 'what will smokers do when there aren't facilities for them'? In a previous company that provided no dedicated location for smokers, they found themselves a spot out the back by the recycling. This resulted in there being a cardboard fire!
Manatū Hauora says
"The Smokefree Environments and Regulated Products Act 1990 (the Act) requires all internal areas of workplaces, licensed premises and certain public enclosed areas to be smokefree and vapefree. The Act applies to schools, early childhood centres, retailers, licensed premises, sports clubs and all employers.
The internal areas of all of these premises are required to be smokefree and vapefree and smoking and vaping is only legally permitted in open areas. Employers/proprietors may choose to ban smoking in their open areas as well."
Therefore, employers get to choose how and where or if they allow smoking or vaping on their sites.
It would be a prime time to engage with people about the issue and how the employees want to deal with it. The employer could offer Quit Smoking options instead. How cool would it be if an employer subsidised quit-smoking hypnotherapy or something like that?
In all things, the employer should offer a safe space, that doesn't necessarily mean seating!