Posted By Bill Elliott I am not so sure it is ALL windows - but there must be fire escape capability - the Building Regs Approved Document B, Fire Safety 2000 edition refer.

Posted By Graham Bullough Perhaps the building regulations have changed for the better in recent years, but I gather at one time in England & Wales it was permissible to have fixed single or double glazing without any escape size opening windows in upstairs rooms in domestic dwellings. In Scotland where, so my Scottish friends tell me, they do things differently and usually better, there has apparently always been a requirement for at least one person-sized accessible opening window from rooms like bedrooms of domestic dwellings. No doubt better informed readers of this thread will be able to confirm or counter these aspects. Double glazing is notoriously difficult to break, as was demonstrated during a BBC "Watchdog" programme some years ago when Lynn Faulds Wood (with full PPE!) tried unsuccessfully to break an ordinary double glazed window panel by hitting it with a chair. It was explained that the air gap between the 2 sheets of glass effectively cushions the impacts and stops the sheets breaking. The programme also demonstrated that double glazing can be broken by using an object such as a screwdriver, chair leg or metal poker to punch such a window adjacent to a corner. The cushioning effect is less at the corners and allows glass there to break. As this also destroys the containment of the air in the gap, you can then proceed to break the glass sheets in the same way that you would for ordinary single glazed windows. (However, you'll have problems with laminated glass whether it's used for single or double glazing.) Although fire fighters will know how to break through fixed double glazing it's worth knowing how to do it yourself in case you ever find yourself trapped behind it. Also, if you've got double glazing at home or work and think that your building contents are secure, I gather that determined burglars also know the corner impact method!