In my opinion, for what its worth, vision panels are there for people to see through before opening the door into someone who may be on the other side. Further, why do the contractors not want people to see through to their site? Do they have something to hide perhaps? Is it in their scope of works? According to a recent thread on this forum you can simply apply wallpaper to the fire doors, but you do need to ensure they are still recognisable as fire doors. If you can source Class One fire rated wallpaper all the better. Glass used in fire doors need to be fire rated and there is a company out there that supplies glass in their Pyro range. No association with them at all. I now feel an interesting discussion coming on.

Building regs Approved doc B provides information on when vision panels are required. http://www.planningporta...br/BR_PDF_AD_B2_2010.pdf There are two reasons why you may require a vision panel. 1. To see if there is a fire on the other side, or 2. as stated above – to see if there is anyone on the other side before you open the door. So this could be in the walls or door of an inner room to enable occupants of the inner room to see if a fire has started in the outer room (not required if there is automatic fire detection in place or enclosure is fire stopped) Vision panels are needed where doors on escape routes subdivide corridors or where doors are hung to swing both ways. There are also requirements for vision panels in Approved document M Access to and Use of buildings which may also be relevant.

you could always keep the vision panal but cover it with an opaque film so you can see if someone is behind it but cant see into the room this is what they use on some hospital wards so you can see if someone is at the other side but you cant look into the ward

There is nothing in any fire legislation across the uk that requires that VP's are kept clear, although there is plenty of guidance to that effect. If your business requires the VPs to be obscured during the works, then risk assess the issue on a door by door basis and introduce control measures as required Maybe introduce staff (and contractors) training and/or instruction, the use of signage, or perhaps organising the works in small phases where minimal numbers of VPs will need to be obscured at any one time. To me, a temporary obscuring of the VPs in a low risk environment may not be especially challenging as long as the RA, control measures and processes are communicated and recorded effectively