Existing House Changes ?

During conversation with the builders today the subject of the alterations to the existing house came up. They seem to think that some things will need doing relatively soon. I am not exactly sure what or why (I was in a hurry and didn't have time for a long conversation). There are maybe 2 more blocks to go before we reach the level for the next floor, and this will take the new bit slightly above the height of the existing roof. This is only on the outer extremity at the front though. It shouldn't cause a problem anywhere else.

We were hoping that the changes to the existing house could all be delayed until the new part of the project was water tight, so that we could use it as storage. The head honcho builder has not been about for the last couple of weeks, but his colleagues tell me he is going to ponder the plans in some detail in order to decide on the order things have to be done. Hopefully all will become clearer when he has done this. Watch this space for an update.