It is quite normal for insuance companies to recommend 4 hour division between non-sprinklered and sprinklered parts of the same risk. (Insurance companies use the term "risk" as a noun to mean the thing that is insured.
But here is an important difference. The non sprinklered parts are insured elsewhere and are therefore, in insurance terms, an "exposure" risk. It is unusual to make recommendations about exposure risks, they tend to be something that is inherent, something that is just accepted for what it is and not something that insureds (those who buy the insurance) can do something about.
But what needs to be established is what are they saying. I'd briefly summarise the levels of recommendations they might be making:
1 A recommendation of something that would bring something up to the gold standard, but they don't actually expect the client to do
2 A recommednation of something that, if not carried out, will result in them changing terms of insurance - for example increasig the deductible (excess) or not giving the full sprinkler discount.
3 A recommedantion that if not carried out, they will refuse to accept the risk and send your client elsewhere.
This is the important point. Something that the bloke who turned up with the torch and the measuring tape won't know, that would be an underwriting decision. Other factors will influence taht decision that have nothing to do with the fire risk: the importance of the customer, the imnportance of the insurance broker who placed the business, their internal underwriting criteria, the profitability of the account, gut feeling etc etc.
Before you start proposing techincal solutions, find the political one. Get the insurance broker involed. I work for one and if someone told one my my clients this, my reaction would be "they have a fully sprinklered warehouse with a 2 hour + party wall, this is much better than 99% of the factories you insure, I would hope that you would consider the neighbouring property to be an exposure risk that is inherrent to the risk, as the 4 hours rule is normally applied to sprinklered and non sprinklered parts of the same risk" and I would expect them to accept that - but then I work for the worlds largest insurance broker and insurance companies tend not to wnat to upset the biggest provider of clients. So, it's more political than technical. I'd get the broker involved and talk to the insurer before spending any money. Or ask the insurer the consequences of not doing it.
