Filling in a gap between brick wall and adjacent concrete platform

[Steven apple]

Hi,

I need to fill a gap (2 inches wide and about 6 inches deep) between my new extension and the neighbours concrete level. The damp course in the bricks is above the neighbours concrete, so I though I could fill it with gravel stones. Should I be worried about rain and fill it with concrete?

 

[Alastairreid]

Better to backfill with gravel.

 

[JohnD]

if there is a risk of damp, cobbles will be better, or as big as will fit with no sand or grit. Large stones are more resistant to capillarity.