We have served many businesses over the years. The majority did not own the building from which they operated. Often there would be either a lease or a long term rental from a landlord/freeholder. The business would have to rely on physical security provided by the landlord. The landlord would seek to keep costs low by not providing substantial physical security features for a general purpose rental.
The first step should be to undertake a risk assessment to understand what risks from which you want to protect the business. You then need to evauate what methods are available to provide the necessary level of protection. One option might be to move the vulnerable part of the business away from the area of risk. However when it comes down to basics there's often no substitute to having strong physical barriers to keep the bad guys out. CCTV systems and alarms are mainly of deterrent value.
By strong physical barriers, we mean better perimeter fences, stronger doors, stronger windows, stronger walls, floors and ceilings. The elimination of intruder hiding spaces will help too.
If the tenant business wanted to undertake works to install stronger physical security in their rented/leased property, they will have to seek permission from the landlord. The business would also have to undertake to fund the removal of security features when they vacate the property. Some physical security measures, such as protective walls, are quite heavy, and some buildings do not have spare structural capacity to take the additional dead weight loading. It may be necessary to lnvolve a structural engineer in the discussions.
You also need to be sure that any physical security measures do not contravene safety regulations and building codes.