How to seal gap between brick wall and ceiling?

Quilly

Our internal walls are brick. 

There's a small gap between the cornice and the wall which allows small dirt and bugs to fall through from the roof space. We're looking to seal up this gap somehow. Is there a way to do this from the roof space? 

I've attached two pictures. The first shows the view from inside the roof space. The second shows the gap between the cornice and the wall. The paper is there to show that the gap is really there as the paper goes all the way though from roof to room. 

  

Nailbag

Hi Quilly. If this is along an outside wall it will be too tight to access from the internal roof space so, you will to access the area from outside. Things to note now is can you access that wall via a ladder (with a spotter) and what is your roof cladding? If its a colour bond (metal) roof, then its its not going to be practical for the average DIY'r. If it's a tiled roof, then it's a matter of removing the last two rows of tiles noting one row will have a single nail securing each tile. Lifting the tile from the front edge will loosen the tile up. This will allow you to then use a general purpose silicone gap sealer from the internal roof space.

A far simpler solution would be to run painters tape along the bricks just under the cornice. Then fill the gap with a white internal flexible gap sealer. To smooth off the finish, give the silicone a light spray of diluted liquid dishwater soap. Then, use the rounded end of an ice-cream stick (about $2.50 for a pack from Bunnings) and run that along the silicon and wipe the excess on to a rag or old newspaper as you go. Now slowly remove the painters tape. You should find the white silicon will blend in well with the ceiling white colour of the cornice. But it can be painted once dried.

Hope this helps