I have a whole wall that I need to block off with some sort of door. I'm thinking that a bi-fold door would be awesome. However, my husband kind of wants a sliding door. I just think how cool it'd be to have a whole wall made up of a door that could easily be tucked away when needed. This would make outdoor barbecues a lot easier. It would sure save me from having to open the door every time. http://www.superiorwindows.com.au/content/Products/BifoldDoors.aspx 

I am just curious, since this is new construction, how you ended up designing such a narrow room. My only suggestion is not to place anything on the long walls that might make the room feel narrower, such as tall bookcases. It would also be good (if possible) if you had some windows along the long walls to make the room feel wider....not just a window at the end of the room.

To change to cavity doors you will need to remove the wall each side of the doors to accommodate the cavity housing. Normal sliding doors would make a difference but the problem with them is they never stay totally closed and they do become quite noisy and annoying. This problem also applies to double cavity doors. The other option is to use bi-fold doors, they won't intrude into the room as much. Do you really need two doors there at all and is the glass above the doorway necessary? My personal preference would be to fill it all in and just have the one door to the room. You could even re-use one of your doors.

I couldn't tick one or the other of the boxes – I think the choice has to be made contingent on so many variables. In fact we have painted timber, double-glazed bifolds (with a fabulous retractable pleated fly-screen) at the end of the dining room leading out onto a terrace and a painted timber, double-glazed slider (with a timber-framed sliding fly-screen) on the other side of the kitchen (but on the same axis) opening onto a raised timber deck. Each works really well in terms of function and aesthetics but they would not be interchangeable as the different locations determined which was more suitable – but they have been made by the same highly skilled window craftsman and have given us nothing but pleasure. And on a hot, steamy evening with both open we have the most wonderful cross ventilation.