I live in western Wisconsin. We can get as warm and humid as the Gulf Coast in August and as bitterly cold and snowy and dry as inland Alaska in January (Anchorage has a higher average winter temperature than ours). As I write this, it’s -8F and sunny at 4 pm, with a wind chill of -30F. And I plan to live in my house year-round (though I haven’t written off the possibility of hauling it to Mexico every winter). So…some of the tiny house systems designed for California, say, are not going to work when it’s -20F. Nor is R20 insulation in the floor. Summer is a little easier to deal with: I can get water to the house via hose, collect gray water in barrels and open windows for ventilation.
We have spent by far the most time in the design of this house on making it comfortable and usable and modern-house-like during the winter. And here’s what we came up with:
1. 2×6 walls, 2×8 floors and rafters for more insulation capacity. I wanted to go with a more environmentally-friendly insulation than spray foam or rigid insulation, which meant less R value per inch (there’s always a trad-off that makes the environmental friendliness possibly less friendly). The 6″ walls were easy because we had already decided to chuck the 8.5′ maximum width restriction. We are sticking with the 13.5′ maximum height so I initially balked at the loss of space with the thicker floors and ceilings, but I was convinced by the promise of warmer tootsies in the winter. Of course bigger wood also equals more weight, but we used 1x6s for some of the studs and spaced the floor joists and rafters as wide as we could. I ended up choosing UltraTouch denim insulation. My builder is not entirely happy because the stuff is IMPOSSIBLE to cut (I’ll post a solution if we find one), but he still says he’d rather spend a day sawing away at the denim than picking fiberglass out of his skin, clothes, eyes, lungs, hair, etc. The floors and ceilings are R30 (double that in the raised floor of the center section) and the walls are R21. Ostensibly. The insulation didn’t fluff up as much as expected, so in the floor we were also able to put in an inch of rigid foam (makes up for my previous environmentally friendly trade-off?). That will probably be the case for the ceiling too.
2. Gray water tank in the floor of the bathroom. When researching for our design I found people using gray water tanks, but they were storing them beneath their trailers or in other places that would freeze solid here on the first 0-degree night. Or it was taking up valuable space under a counter somewhere. Our solution? We raised the floor 8″ in the bathroom (like we did the center section of the house) and created a pocket for a 30-gallon tank. So it has ~R30 insulation below it and around it, and I’ll be able to access it through a panel in the floor. I wanted to make sure it could be easily removed if I needed to replace it, or for any other reason. I’ll also open the panel to open the drain valve when I need to pump out the full tank. I chose 30 gallons sort of randomly – I wagged that I’d use about 4 gallons a day on average, and I don’t want to have to drain the tank more than once a week. You can order tanks of all shapes and sizes from www.tankdepot.com (be sure to order a bit in advance – it takes a few weeks). The drain is 2″ PVC with a plug that I’ll open to transfer the gray water to a portable tank in the back of a truck, which I’ll then haul to the local wastewater treatment plant. Voila! Easy on paper, the practice is of course yet to be tested. It of course also remains to be seen how quickly I’ll fill up the tank. If I end up having to pump it every other day it might not be much fun either. I’m not going to have any black water – my toilet will be a Loveable Loo type affair. I lived in a yurt with a bucket toilet for a couple of months and found it to be a very good solution.
3. Fresh water tank in the loft above the bathroom. This tank also needs to be within the insulated envelope, and I was more willing to give up storage space in a less accessible loft than under a counter. I haven’t purchased this tank yet and we haven’t completely figured out how and where it will be filled, but I will have an RV pump (I’m looking at a Flojet Quiet Quad diaphragm pump) and not rely solely on gravity. It will be another 30-gallonish size.
4. Kimberly wood stove for heat. How to heat? Big question. Originally I wanted the house to be off the grid, but the economics didn’t work out. Even so, electrical heat was never a consideration (although I may have a small baseboard heater that I can turn on just high enough to keep my house from freezing if I leave for a day or more). I read a few blogs that said the Dickinson propane stove so beloved in many tiny homes isn’t really up to the job of “real” winters. Kerosene is stinky. I was initially opposed to wood heat – a lot of work to gather and haul wood, it has to be practically in the center of the room to meet clearance requirements, constant cleaning up of wood dust and detritus, black soot all over hands and clothes if I get within 6 inches of the stove, having to get out of my cozy bed every three hours to stoke it, heavy, etc – but then I found the Kimberly. It’s expensive, yes, and I’ll still have to gather and haul wood, but it’s super efficient and can purportedly burn for 8 hours. It’s also lightweight and doesn’t require much for clearance from walls. I’m also not as worried about heating myself right out of the house as I would be with a traditional cast iron stove. I’m super excited to try it out.
5. Active exhaust and passive make-up ventilation. I’ve been kept awake at night after reading horror stories of tiny houses and condensation. There’s very little out there about exhausting air from or providing make-up air to tiny spaces. I looked into HRVs (one tiny house builder in Quebec that I corresponded with installed the Lunos e2, which is supposedly sized right for a tiny house) but they’re expensive and my builder wasn’t convinced that we needed to go that far with it. Heating with wood will dry the air, but will it be enough? After much researching, hemming and hawing we’re going with a bathroom fan (Panasonic WhisperFit), a stove hood (Broan Allure) and a passive air inlet (Therma-Stor Fresh 100). The Kimberly stove has its own fresh air inlet, but it’s contained within the stove. I really hope this works, and I’ll probably find out next winter. If it doesn’t, we might be re-thinking that HRV as Plan B. Either way, I’ll post how things are going. That goes for all of these experiments in tiny house winter living.