Waterproof Garage

[Gwyndaff]

I have a good quality garage with the following:

Single brick Walls
Garage Door
Good quality slate roof
Broken Window at rear

Before I moved into the house, earth was placed around the garage from the sloped garden, above the damp course. I have since 'tiered' the garden but have been unable to remove the earth from around the outside of the garage. I intend to fill in the window with brickwork.

My question is, how would I waterproof the garage, I seem to get a lot of water ingress from the walls and obviously under the garage door. DO I need to put a second layer of bricks in or would I be able to do it with some kind of chemical or paint.

Thanks in advance for your help.

Carl Evans