Mattress Underlayment

X3 on the Hypervent Aire-Flow:

Link

Rob

We haven’t personally had a condensation issue either. Although no long term winter camping. But even with a month long trip at warm day temps, heater needed in the evening and mornings it wasn’t an issue. But was a dry climate

Maybe a option if needed would be the snap lock sports court material. Seems it would provide an air gap.

The biggest things folks don't do is allow enough ventilation at night when they are sleeping. Leave a roof vent crack about a 1/4 turn and a lower window like the pass through window cracked about a 1/4". Another issue is to let the temp inside the camper drop at night. The lower the difference between the outside temp and the inside temp the less condensation will try to form. Between these two, I've never had a condensation problem either on the bed or on the windows.

When you cook, make sure you open the vents and windows even more, try to use the stove vent if cooking something that steams.

All this said, I did add a 1/2" foam board under the mattress to provide a bit more insulation since I camp in temps down to 0*. Takes two pieces so under $20. The scraps can be used to make pieces that fit snugly in the windows you don't care about seeing out.

X2 for hyper-vent. Used it on the boat for many years, in the camper, and in the house. Defender Industries, Waterford , Connecticut. About $9 per foot

Hyper-Vent from Fisheries Supply ... 39" wide, by the foot. Figure your length and place underneath mattress (mildew is a big problem in marine mattresses, especially laying on a fiberglass bunk).

there is an overlap beyond 39" of the upper layer. two lengths side by side work for a queen mattress.

We use the froli system and have been very pleased but I can’t compare it to anything else because we added it on day one. Never an issue with condensation even in below freezing weather.