Thanks for the replies guys. Unfortunately, TEMP, next doors roof is very old. The mortar is already coming loose , so don't want to touch it.
GUS, I'm not totally sure what you mean, it sounds Interesting though, would you mind showing me an example of s9meyhing similar, just fir my own clarity.
And Tonyshouse, that was original plan but the bricks are so soft and damaged, it work work.