Thread: Best base under pavers for water flow

We have a 30yo high set house cut into the hill. Back corner is back filled 3m along each wall to a block wall up to floor height. The back of the house has a 1 metre wide access with a 2 metre high retaining wall which is covered by a 3mX12m deck. There is a concrete paver patio over the back 3m filled section while there is large river pebbles down the side of the house on the filled section.

The problem is when we have heavy rain the water pours down from the hill at the back and collects on the patio. The previous owner have deliberately graded the pavers to take the water under the deck and the access below floods and water can and does come under the back door. We also get water in the downstairs store room in the back corner against the fill. In very heavy rain the water on the pavers will reach the wall of the house and the river pebbles around the corner also slope toward the house.

I don't relish the thought of digging down 2 meters beside the walls and resealing the walls and we only have the damp problem after flooding rain. Obviously I have to grade the everything away from the house and deck to start with but what would be best to prevent water penetrating the ground ? _ Would I have to go the full concrete bit for the patio and down the side say a metre wide. or would suitably compacted base and pavers be enough to take the water away? I'm looking to the most effective/economical and time involvement solution