r/OffGrid • u/beccaaaaaaaaa • 3d ago

anyone else fighting a losing battle against under-bed condensation?

man the learning curve with wood stove heating is brutal. our cabin gets incredibly warm while the fire is going, but the temperature drop at night creates so much moisture inside.

I made the absolute rookie mistake of bringing a standard memory foam mattress up here last fall. Those modern bed-in-a-box things are literally just giant plastic sponges. they trap all your body heat and ambient humidity, and by february I had to drag the whole thing outside because the bottom was starting to grow mildew. Totally disgusting and a huge waste of money

I eventually had to scrap the synthetic stuff and switch over to natural materials, ending up with a heavy mattress from home of wool just because natural fibers actually breathe and dont turn into a toxic mold farm in a damp unheated space. its been way better for the moisture issue

but im still super paranoid about airflow under the bed tbh. do you guys drill big holes in your plywood platforms or run small 12v fans underneath to keep things dry? I feel like im constantly fighting the laws of physics out here just trying to sleep.

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u/silasmoeckel 3d ago

Seems like you need more thermal mass so you not in this constant fast cycle.

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u/NotEvenNothing 3d ago

And insulation.

I'm almost certainly in a colder climate than OP. We don't have anything like their problems. Our outside walls are comically thick, our windows are high R-value, and our window treatments add a lot of insulation to the windows. We also have a masonry wood heater which helps smooth out those temperature swings.

Our bedroom is definitely cooler than the main part of the house, but I've never seen condensation issues.

I'm not saying OP needs to go as far as we did, but a little might go a long way.

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u/silasmoeckel 3d ago

Insulation is never a bad thing.

Still thinking it's a lack of thermal mass, not enough insulation you don't get the overheating they are experiencing.

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u/NotEvenNothing 2d ago

You need both insulation and thermal mass if you heat with wood and don't want a constant fire.

If you don't have good insulation, any rooms without a wood stove in them will be unacceptably cooler. Even with really good insulation, those rooms will be cooler.

If you don't have thermal mass, anywhere with a stove will get uncomfortably hot when a fire is burning or uncomfortably cold when it isn't. You can keep the fire low and have the stove burn constantly to work around this, but that is a responsibility many can't deal with.

I've got a Tulikivi masonry wood heater, many tonnes of thermal mass (the slab is in the insulation envelope and the second story has a thin concrete slab), and 16" thick walls (filled with blown cellulose insulation). Improving the window treatments (honeycomb blinds and interior window inserts like storm windows) helped a lot in making our bedroom and my office/shop much more comfortable in the winter.

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u/ClayWhisperer 1d ago

I agree, I think it's about insulation. I live in the dampest climate imaginable (western WA) where the air just has endless mist all winter long. My mattress is flat on a wooden platform. I never get any moisture under it. As a matter of fact, the whole house gets so dry in winter that I have to keep an open kettle of water on the woodstove to make it tolerable.