Yes there is a business continuity thread separate to the fire safety one, however you must identify that fire can destroy computer hardware, that is not something that you could claim to be outside your field of knowledge and also fire damage to other contents/parts of the premises. So there is absolutley no excuse in not then identifying the control measures to reduce/remove the risks associated with the fire hazard. Not telling the customer that fire can damage their business by destroying their information is negligent, no less. Whatever FRA is being carried out ignoring that you have idenitified other risks, than are required under legislation to be controlled by the responsible person, is not professional. I refer again to my potential case. Your defence is weak, very weak, unless your contracts specifically say that only legislative areas will eb looked at and any other risks that you doscover will be ignored. I can't see many people being happy with that. I am amazed that you think it is acceptable to know that your customer is at risk of losing their business, because no controls are in place for information storage in the event of a fire, and are happy that you aren't goingt ot ell them, worse still that you would refer to legislation designed to force a level of RA to hide n behind on the basis that only those forced areas are to be reported on. Disgraceful, absolutley disgraceful. I do hope you are making loads of money from your half-hearted and half-done RAs as the businesses you have worked for may be seeking compensation later. I fail to see why you can't accept that it is good practice, and demonstrably professional to boot, to tell your customer about risks (that are after all due to fire) but beyond the legislative requirements. I bet you never recommend any extinguishers/signs/alarms that aren't actually REQUIRED because to have more is better, or because you make more money from them. Go on think about giving absolute basic, nothing more than is actually legally required, advice and see whether you think that is right either?
I do like the way you read kurnal's comments as being fuly supportive of yours, actually I read them to be supporting mine. He says there is danger in partly covering something and that by saying something he does not absolve the business form responsibility, that is equally true of your FRA by the way - what he does not say is that he would therefore not tell them at all, quite the opposite form my reading. In the case of back ups for computer information you would not be partly covering the issue at all, a quick question will determine if the information is critical to the business and if they have off site back ups already. From that a RA and control suggestion to carry out back ups is fully covering the risk. Simple. Indeed if you at the FPA Business Fire Risk Assessment guidance business continuity is clearly a part. Maybe the law doesn't require consideration of this, but bet your life your customer would have thought you would - especially post event if you never mentioned it - litigation would be in their minds for sure and I have little doubt that most judges would agree with them.
Where do you stop? Well you stop when you have identified all the risks from fire and their possible controls, that is what you were there to do, if you spot risks not connected with fire you mention them with the 'not my science' caveat, but fire is.