Most warehouse, commercial or industrial premises will have some form of roller shutter doors.
The quality and security of the doors has moved forward a great deal in the past 20 years. Not that we wanted to when we were younger, but it wouldn’t have taken much to break in. A bit of pressure halfway up most roller shutter doors was all that was needed.
Thieves obviously realised this and break-ins occurred. Whilst pressure on the door was usually noisy, elementary physics usually came into play with a fulcrum. Most roller shutter doors had a basic padlock on a chain on the inside. If a small opening could be gained at ground level and a fulcrum used (thin metal bar) then access could be gained underneath.
The problem as far as commercial insurance is concerned, is that a lot of these older style doors still exist. Most business insurance policies will have some sort of security condition on stating the type of security that MUST be in place on roller shutter doors.
It is worth checking this very carefully to ensure you comply. Close shackle padlocks are OK as these are in common use on roller shutter chains. But, some insurers will look for there to be additional locks (not padlocks) on either side of the doors. Some will also look for the switch (which may well be key operated) to be kept behind a locked metal box (which would have to be welded onto the frame of the door).
If you are sensible enough to have arranged your insurance through a broker, get them to explain the security clauses for you. If you have simply bought direct from a site that promised cheap public liability insurance etc etc, then try and speak to the insurance company direct.
Whether you like it or not, if you don’t comply you may not get your claim paid out.