Water Proofing Single Skin Garage (Internal)

[Gwyndaff1974]

Hello forum members, I hope you can help me with my problem.
I have a single skin garage at my home which was built before we moved in. On the right side of my garage there is packed up earth with retaining walls about 1/4 of the way up from the ground.
On the rear side of my garage there is packed up earth about 1/2 way up from the ground.
As you can imagine I get dampness, more so from the right side, at ground level and part way up the wall.
I want to be able to damp proof the garage but only have full access to the interior walls.
Could someone advise me on the best way to achieve this? Obviously I want to keep costs down as low as possible.

 

[PrenticeBoyofDerry]

I assume that the walls will not require insulation or tanking up but you just want to stop the damp walls?
The best way would be to remove earth and barrier at that point, then replace earth if it's part of retainment.
The only other solution would be to coat the walls with damp resistant solution, but you may still get water ingress at floor level.