Moisture problem under beds

[Godtomley]

On our Thor Cub, with fold out bed ,we use a memory foam mattress. Our problem is that in cooler or cold weather moisture accumulates on the bottom of mattress. I know why , just haven't found a good solution. Any & all ideas greatly appreciated.
Thom

[Superslif]

We had the Cub from 05' till 12', but had the regular foam mattress. Never really noticed it wet under the mattress, and did a lot of cooler weather camping. But I did notice moistener on the canvas tent ends. I would wipe it down if I got to be too much or when closing it up. Our new Aerolite hybrid (2013) , we added a 2" memory foam topper to the mattress, and I can't recall any dampness.

[bikendan]

in the 7 years i've owned my Roo and 9 years on hybrid forums, this is what i've learned about this issue.
some hybrids have mattresses with a fabric bottom and some have ones with a vinyl bottom. both will get condensation underneath but the fabric ones absorb the moisture, whereas the vinyl ones simply can be wiped off.
many have tried different solutions. the best being products made for boat sleeping berths, due to being on water. but they are very expensive.
i've tried Reflectix, foil-backed foam insulation and other things. the key is to somehow allow for air between the bottom of the mattress and the top of the bunk platform. i now use a couple of wool blankets under the mattress which is able to create a bit of air space. doesn't completely eliminate it but the blanket is what gets damp instead of the mattress.