I have a garage @ the bottom of garden.
The smooth cement floor is about 200mm below garden level
especially in winter there is a fine layer of moisture on the side of the floor that is next to the garden facing internal wall.
Damp occurs in an area of 3 ft from the internal wall
Other wall is joined to nxt-doors garage & there has never been any damp
within seven feet of that internal wall.
During summer there is white salt marks on side of floor nxt to damp wall.
Internal wall has damp @ a height of 3ft as you walk in from the garden( white salt marks more evident in summer).
Then damp slowly tapers down as you walk away, 8ft from entrance to a height of 1 1/2ft.
The cement on wall becomes very powdery, floor cement notso it is all in one piece no powdreing or cracks, just surface water.