Nano Rats advice please

[Danny McG]

it might make more sense for him to camp in one room in the house and then ratproof that. from experience, entire houses are near impossible to ratproof (especially if they're old. the houses, not the rats). he could then fill all the holes, gaps around doors windows etc with fast setting sealant.

he could then forget the little hole in the wardrobe that the rats eventually find and get in through

I just want to have him asleep and holed up somewhere feeling safe and a bit smug .
Then wake up in agony losing half a foot. Hobbling off whimpering into a cold and clammy pre-dawn after a frantic battle. Desperately in need of medical attention, shelter and a way to hit back at the computer.

Initially I wanted guidance here on how to block a drainpipe but now I've some good plot ideas.
Ta all