 Do control joints in two-it-up concrete external walls require fire protection? Of course, we're talking about walls which need an FRR, like those on or close to a boundary, which is a fire source feature. Yes or no? Well, here's C3.1 application of part, and you can see there in A1 that control joints between precast concrete panel walls don't need to comply with part C3, so long as they're not larger than necessary for the purpose. But then we turn to C3.16 construction joints, and C3.16 says, if you have a construction joint, like, say, a control joint, in a wall which needs an FRR for integrity and insulation, so that's the second and third numbers in the FRR rating, of course, then you need to protect the construction joint, unless it's a joint in fire-protected timber system which has cavity barriers. Now, it might seem that the BCA has told me I don't have to do something, but then straight away tells me that I have to do it. So, which isn't? Well, this is one of those times when it helps to remember that often a BCA clause is written to cover more than the situation that you're thinking of. Let me show you. Here's what C3.16 is about. These are the sort of things that need to be protected. Control joints and things like that, mentioned in the top box, which are in walls, beams, floors, and so on, mentioned in the bottom box. It has to be in both things in order to be applied to C3.1. Now, what C3.1A gives a concession for are these things that are in green in both the top and the bottom lists, and these things are a subset of what's listed in C3.16. If you have a control joint in a steel-framed clad external wall, for instance, it needs to be protected. If you have a control joint in an internal concrete panel lift shaft wall, well, yes, that needs to be protected as well. But if it's anything that's green in both the top and bottom lists, like a control joint in an external precast wall, then under C3.1A, you have a concession and you don't need to provide protection. So the answer's no. Your external precast concrete wall or your external masonry wall for that matter, if that wall needs to have an FRL, it doesn't need protection for the control joints, so long as they're not larger than necessary for the purpose.