Patio slabs

Hi
We've had a patio laid level and built a log cabin on it
We have a treated foundation beam on a dpc strip, I've sealed around outside with builders silicone,
The slabs are butted up with no pointing, maybe a 2-3 mm gap
Now, after rain there appears to be capillary action with water running along joints and under dpc and into cabin (no wooden floor laid yet).
My question is
Would laying the sika setting sand for narrow joints solve the problem if not, any suggestions please

You're unlikely to stop water running into the cabin if its laid on a flat patio that is bigger than the cabin. Is there any way you could lever the structure up and slide some concrete blocks under it to raise it off the patio surface?