Warm and moist air on the inside of your rooftop tent. Nice and cold air at night on the outside. Those two environments meet at the tent walls and floor. And it’s where you have a moisture control problem in the form of water condensation. You may need to address this problem.
You are probably sleeping on top of a 2in thick foam mattress in a sleeping bag. That foam mattress will absorb some of the nice warm, moist air from inside the tent. But it’s also touching the cold floor causing water to condense inside the foam mattress. The weight of sleepers on the mattress is also helping the condensation process along. You will notice this problem when you go to fold up your tent . Compress the foam mattress and water starts dripping out. The solution is to get some kind of insulation between the floor and the foam mattress. This keeps the mattress away from the cold floor and eliminates (or mitigates) water condensation.
I’ve had success using a torso length piece of reflectix (cut down a car sun shade to 2-3 ounces) under my pad or on top of the pad. Before anyone down votes (because reflectix and paracord are normal stables of the bushcraft afficionados)…
- The surface is not going to reflect radiant heat when touching the body, however people forget that reflectix is bubble wrap encased in two layers of reflective Mylar. Each of those bubble cells is a dead air space.
- The reflective surface will reflect radiant heat coming off the sides of your body.
- It doesn’t matter that it doesn’t breath and is a vapor barrier. All your pads are vapor barriers.
- Reflectix does not have a 4.2 R-value as claimed by the makers. To get that R-value you need a very specific set up with a very specific air gap between the heat source and the product. That claim only pertains to its use in building.
- It may not be the lightest solution (it actually may be) but it is definitely the most cost effective per ounce.
Reflectix works most effectively with an air gap. You are not going to have an air gap, but it might not matter. Maybe good enough is the way to go here. Check out Reflectix at your local Home Depot store.
What about other moisture control issues in a rooftop tent, like the walls and roof? How would you deal with this problem? Consider moisture absorbers. The first two below are chemical moisture absorbers. The last one is a microfiber towel that is super absorbent.
- Star brite No Damp Dehumidifier 12 oz Bucket: Sports & Outdoors
- DampRid FGAM86LV Moisture Absorber, Lavender Vanilla: Home & Kitchen
- Rainleaf Microfiber Towel – Fast Drying – Super Absorbent – Ultra Compact
Get more information on those products at the materials list page.
These crystals in the Star brite and DampRid absorb moisture from the air. They dissolve in the process and drip into a lower container. The microfiber towel option also absorbs water when hung out in the tent at night. Just wring out the towel in the morning and hang in the sun.
There are other ways to mitigate the moisture control problem. Hang moist clothing outside of the tent. Ventilate well. Avoid putting your tent right next to a body of water.
What happens if your tent leaks? In the video below the Yakima SkyRise rooftop tent leaks at some of the seams. He uses SeamGrip seam sealant to fix the problem. An equivalent at Amazon.Com is Gear Aid Seam Grip WP Waterproof Sealant and Adhesive for Tents and Outdoor Fabric.
Yakima SkyRise RTT Rain Ingress Update – YouTube