We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember geraldthehamster
saying something like:

Oh come on, there must be a way we haven't thought of.

Easy - peasy.

Flood the underfloor space with wotter and on it float a carpet of
sticky foam pellets that will stick to the underside of the joists and
floorboards. Drain away the moisture, and there y'go.

It's so good I might just patent it - or I might not bother.