indoor slug activity - help!

[BlueChampagne]

Nearly every morning we come down to slug trails on our carpets in the living room. This is despite DH doing slug patrol (and evicting the culprits) while I'm up feeding DS2.

We have tried salt defences but can't find where they're coming from. Surely under the floorboards it would be too dry and dusty for slugs?

Any tips?

Gap in window/door frame? Where do the trails start from?

SAS spray where you think they are entering - but you need to keep reapplying :-(

They seem to be coming from under the sofa, which is against an internal wall, and we haven't found any obvious gaps. Will look into SAS spray - thanks.