I'm working on designing a wofati house with a large attached greenhouse and a small root cellar. For drawing the model I'm using the free version of google sketchup and will soon post some pictures of what I've got so far.
Here's a link:http://sketchup.google.com/3dwarehouse/details?mid=9982c503b9dbc54161a67ce71ec9d046& to a draft from a few days ago. I've worked on it since then and will be posting updates shortly.
I'm hoping that by putting this out here to all you permaculture goofballs, hopefully people who have more experience than I do can offer constructive criticism. In any case, I'm highly enthusiastic about wofati structures and would like to contribute to the proliferation of practical designs for earth-integrated structures.
Since I don't know what kind of slope or elevation will be at the actual site, (since it hasn't been found and purchased yet,) getting too far into this design project may be somewhat premature, (but still really fun.) Ideally, it will be built on a south-facing hillside, but I'm hoping to come up with a design that can possibly be adapted to a flat site or maybe west- or east-facing slopes.
Here's a couple pictures showing the basic design of the structure so far:
(moved to bottom of post and resized to avoid obnoxious screen stretching)
As you can see, the roof is only just begun, but I wanted to get some feedback on the spans and diameters before moving forward. Right now the model uses 14" diameter posts spaced on center 6' apart along the perimeter of the structure. The longest single uninterrupted span is 24', and consists of the entire length of the peak of the gable roof. The other spans are all 6'-12'.
Some of the next steps would be to finish adding the vigas, and shoring up the walls, then a cardboard/epdm-rubber/cardboard layer hugging the structure, then 10" dry dirt and 2" insulation, then a cardboard/epdm/cardboard layer defining the thermal mass umbrella, then 18" wet dirt + polyculture seedlings.
Do you think that the spans and diameters of the posts and beams used in this model are appropriate, inadequate, or overkill?
If you were to pay extra for the epdm rubber roofing instead of using polyethylene on just one of the two water-proofing layers, which would be your priority, (the layer that hugs the structure, or the layer that defines the thermal mass)?
How functional do you think a green house on the north side will be? I was thinking of making the back wall of the green house out of stone maybe, is that crazy?
Also, is anyone else familiar with sketchup and have you found an easy way to make a somewhat organic-looking sloping hillside to work with?
Joined: Jul 27, 2012
Location: Oakland, CA
Wait until you have a site and know the topography as it will totally change your design.
Don't put a greenhouse on a north side.
Google "span table" - all will be revealed.
If you haven't built anything before, try an outbuilding first for practice. You will need cover for your materials while you build anyway.
I'm going to completely ignore your first piece of advice and merrily continue designing without having a site. I fully expect to have to radically change the design once I have a site, but until then, I'll continue practicing. I'm looking specifically for south-facing hillside, and if that's what I end up with, I'll at least have some dreamy designs based on roughly similar conditions.
An uphill greenhouse on the north side is a feature of one of Mike Oehler's similar designs that I'm working off of:
I pushed the greenhouse roof up higher in my model in the hopes of catching more sun and being able to catch rainwater. I anticipate having a fair amount of sunny vertical grow-space near the back, and progressively shadier space approaching the house. Even if it's not as effective for growing plants as I'd like, I think it will keep the house warmer and drier than just having an uphill patio with no roof. That said, I'd be happy to hear some suggestions for doing it differently.
Thanks. After looking up span tables, if I read them correctly, it seems like my model is over-built. Maybe it won't cave in on me if a herd of moose decide to hang out on the roof in the middle of winter.
This won't be my first building project. I've built a few small outbuildings over the past few years and worked on a couple different (comparatively) huge house construction projects for friends. It was decent practice, but both of them were way heavier on the concrete and other toxic materials than I would have liked. A shed for storing materials and tools will certainly be a good first project once land is acquired, but it probably won't be an earth-integrated structure, and so it doesn't excite me nearly as much.
It's "so huge" (actually the indoor living space is under 700 sq. ft., not including the 120 sq. ft. root cellar or the 500+ sq. ft. uphill patio/greenhouse) because it's meant to be inhabited by more than just two people. The greenhouse is probably too big, but that north wall just looked too close when it was half that size. Also, it all looks bigger now than it will because the posts will be buried 3'-4' deep. That said, smaller is sexier, and so I'll work on a truly tiny version too.
Joined: Apr 13, 2012
Location: Kansas Zone 6a
Keep playing with designs. Design one for a north slope. Design one for flatland. Think about span and how to work columns into your design. Having posts on 8 foot grid can be a real pain if you don't design the rooms around them. Think about heat. Think about ventilation.
Keep those ideas and requirements in mind when looking for property--having the right timber on site is worth a lot.
google "walapini" for more ideas for the greenhouse design portion. good for maximizing solar gain.
I would want the good liner to protect the mass. And I would use 3 layers of 6 mil instead of 2 in other places. cheap insurance.
http://www.treebytheseafarms.com/ "You must be the change you want to see in the world." "First they ignore you, then they laugh at you, then they fight you, then you win." --Mahatma Gandhi
"Preach the Gospel always, and if necessary, use words." --Francis of Assisi. "Family farms work when the whole family works the farm." -- Adam Klaus
Thanks Scott. Your feedback is appreciated. I will indeed keep playing with designs and posting them here.
I would imagine that having posts in any kind of formation could be a pain if the rooms aren't designed around them. I anticipate doing lots more thinking and rethinking of floor plans. I just finished reading Homing Instinct, a book about design from the Yestermorrow folks in Vermont, and so the concept of spiraling up (or down) the "design helix" is still fresh in my mind.
For heat, besides passive solar, I'm hoping a rocket mass heater will be a winter heat-source as well as a cook stove, and I'd like to implement a bbq window (only rocket stove(s) instead of a bbq pit) for summer cooking while keeping the heat and moisture outside. I'm hoping to put the shower/tub in the greenhouse for ventilation reasons as well.
This "walipini" is something I'd never heard of before. Very interesting. The idea of two layers of plastic roofing, one above and one below the structural wood, seems like a good way to avoid rotting the wood while the air-space in between acts as insulation if sealed properly. I wonder, would it hurt to increase the air-space / roof-pole-diameter above 4", say to 6"? Would the advantage of being able to space them further apart be offset by the height of the shadows? Maybe I should just stick with the recommended dimension for now...
Hmm, protecting the mass with the good stuff makes sense. What other places would you put a third layer of poly?
Here's a couple more pics of the paper-thin version of the smaller (16'x16') wofati + (8'x8') root cellar + (16'x16') greenhouse that I'm working on designing.
The first picture shows a somewhat unimaginative earth berm, the south-facing wall of windows, the gable, and a rocket mass heater whose thermal mass bench runs along the west wall and out into the greenhouse. The tube poking out on the right is supposed to be cool-air-intake from daylight, (a component of the attached root cellar,) but it shouldn't be hard to put that somewhere less obtrusive... Haven't figured out the other half of that equation yet, though, (the warm-air-exhaust to daylight.) And I haven't figured out an elegant way of dealing with that post right in the middle of the house yet, either...
The second picture shows the north side and the greenhouse, including a ladder built onto the middle post leading up to the keyhole garden, the bbq window, and the thermal mass of the rocket mass heater making up the floor of the shower.
It's a start. Hopefully other folks find these sketches somewhat helpful.
More pictures of updated design: 16'x16' wofati house + 8'x16' root cellar + 16'x16' greenhouse
The first one shows the front of the house. Cob bench encasing rocket exhaust on the left there, space for yoga on the right. Those dotted lines on the right making a box around the yogi's leg is supposed to be a bed that folds into that wall when not in use.
Second pic shows a view from the growing area of the greenhouse looking down into the house.
Third pic shows the greenhouse from the east side. From left to right, note the bbq/rocket-stove window next to the stairs down into the house, the tub/shower, ladder/stairs up to the growing area, the compost toilet closet with external access hatch, and finally the rocket stove mass heater exhaust on the far right.
One thing I didn't think enough about initially is storage for clothes. I'm considering adding a bit more bedroom-type storage space, perhaps a kind of dresser built into the floor, but the only logical space for that would be underneath the floor of the yoga space/ fold-out bedroom, and I'm not really sure how to go about engineering such a thing in a way that would leave it accessible even when the bed is folded out... yet.
I suppose having room for a bicycle-powered washing machine somewhere in the greenhouse would be cool, but perhaps that's a device better shared amongst a larger community rather than a single tiny household anyway. At least there'll be enough room in there to hang a clothesline.
Any thoughts, feelings, comments, criticism, or concerns anyone would like to express while there seems to be a pause in my rambling?
Sun Arc Wofati This design is admittedly pretty whimsical, but I had a lot of fun with it. Plus, it's actually pretty simple, basically a 16'x16' cube with a gable bisecting it diagonally. Light, air, and views from four directions. Probably not enough earth-sheltering.
"First Wofati" Redux This is an attempt to replicate Paul's First Wofati, with some slight modifications, (namely opening up and popping out the gable end a bit, and putting a totally unrealistic greenhouse over the uphill patio.)
Wofati Northeasti This is my latest, and the one I'm most excited about. Finally broke some of my symmetry fetish with this one. Being situated on a northish-facing slope potentially makes passive-solar earth-sheltered house design even simpler. Since the uphill patio, and all the windows looking out on it, face south already, the roof can be a simple shed without a complicated gable. Admittedly, the gable is helpful for getting more light, air, and views from other directions, but I think rotating the rectangle of the house footprint 45 degrees, (meaning having a south corner instead of a south side,) and thereby having two walls, (southeast and southwest) with windows looking out onto the uphill patio can accomplish some of the same effect. This design doesn't illustrate that perfectly, because I was also trying to incorporate a walk-out balcony/yard kind of thing from the second floor, but maybe you get the idea.