How to build a yurt platform - part 2

We've been digging holes that we marked out before. Here's the template for marking the hole, and an example of the marking:

The plan is that each hole is about 18" x 18" on top, and at least 12" deep. In some areas there's fresh fill dirt, which isn't stable enough, so we will dig deeper where required. Other areas are already cut to firm subsoil, so it's 12" of difficult digging and you're done.

The 12" depth is based on the specified frost depth in this area, as specified by the county's building department. In the previous location the yurt was directly on the ground, with only an inch or two of sod removed, and that worked for 6 years, so this isn't strictly required. But my carpenter friend pointed out the high clay content of the soil and said it would swell with the rains and freezing, so some depth is a good idea.

The ground is glacial till, so it's a well-varied mix. Plenty of clay, silt, gravel, and small boulders. The biggest rock we've pulled out so far was so heavy I had to roll it out of the way. Each spot is different, which is amazing to watch.

We started digging by hand, with a couple shovels and a mattock. I soon added a digging bar, because the mattock couldn't reach the bottom of the holes.

With all 5 of us present, the adults digging and the kids making trouble, we can dig 3 holes on a good day. In one area we hit some roots and it took 2 days to dig 2 holes. At this rate we're talking at least a couple weeks just to dig the holes. After that we have to fill and tamp, set the pier blocks, frame the platform, lay down the flooring, and assemble the yurt. That's a lot of work to do, and we're stuck on digging holes! Still, I like the idea of pointing to the holes and saying "we dug those ourselves!", and some people pay money for the gym while we get to play in the dirt for free-ish.

I thought about hiring someone with a backhoe to dig the holes out for me. That could go really fast, but I think I'd end up with much larger holes than I want.

Yesterday I rented a 2-person gas-powered auger. The biggest bit they had for it was 12" diameter, so the hole isn't as big as we want. But I figured it would get us started. The machine is still a lot of work - it's heavy and it knocks you around as it digs. Rocks less than a couple inches get churned out fine, but over 5" the machine tends to stop digging. Roots slow it down, but it goes. Even the kids helped:

Here Dylan helps us measure a hole:

After digging a 12" round hole with the auger, we still have to shovel the loose dirt in to the wheelbarrow and haul it away, and widen the hole to 18" square. It's way easier, but there's still plenty of work to do. We did this with a couple holes to see how it would go, and then augered out the remaining holes (save 1 because of a big rock) before returning the machine.

The next size up at the rental place is a Toro Dingo with a 24" auger on it. That's about the size of a circle that circumscribes the 18" square we want, so it would be a one-shot deal. The hole is bigger but at least it's a neat, round one. For now we'll dig by hand, though.

Back in the stick house

We spent 3 nights in Coach in the back yard. It was awesome. I loved being close together as a family.

You have you have to keep up with the cleaning, or the space becomes impossible very quickly. It's not hard because the space is small and there's not much stuff.

We moved back in to the house when the graywater tank got full. We could continue if we want to drive to a dump station every few days or so, but I don't really want to do that. We learned a lot from the experience, and have a list of changes we want to make to the RV to make it more comfortable.

Watching music videos in Coach

We've moved in to the RV, at least for tonight. Just in the back yard, but still. Cooked dinner. Brushing teeth next.

The falacy of solar power

That title is a bit inflammatory. It should be "The falacy of solar power on grid-tied homes." Instead of putting solar panels on your roof, here's why you should invest that money elsewhere."

I'm a big green geek, so I've always been drawn to solar power. Now as I am planning to build a new home for my family, I am asking if I should incorporate solar power in to my plans. I have come to the conclusion that putting photovoltaic panels on your roof is almost always a bad idea. Bummer. Read on to see why I think that, and what I think should be done instead.

First, some context. I'm talking about common single-family houses in North America, connected to the electrical grid, where the power company is required to do net metering.

Net metering means that any power you produce in excess of your consumption is sold back to the power company. The nice thing about this program is that you don't have to bother with batteries and charge controllers and transfer switches. That's a lot less equipment, a lot less complexity, a lot less cost. The big items are then the PV panels and an inverter. Any extra power you produce is pushed out in to the grid, and then consumed by someone else in the system. Similarly, any power you consume that you don't produce is pulled from the grid.

With net metering in place, the power you produce isn't really for you to use. Your PV array is just another producer on the electrical grid, while your house is just another consumer. It doesn't matter when you produce, when you consume, or how much. The difference is just settled in dollars.

It doesn't really matter where your PV array is, either. You can move your solar panels + inverter to a location with ideal characteristics - lots of sun. But why limit yourself to just your house roof vs. shed roof vs. a dedicated pole on the ground? Why not your neighbor's house, if it has good sun all day long?

I live in Western Washington, which is known for being overcast a lot of the time. Why not put a solar array up in Eastern washington?

Being close to the equator would improve the output of the panels, so why not put an array in New Mexico?

According to the Department of Energy, Californians pay about twice as much as me for their power. They also have more sun. So why not put up panels in California, sell the power there at $0.15 / Kwh, and use that money to buy my cheap Washington power ($0.08 / Kwh)?

I can also aim for locations that produce their power in ways that pollute. If my power is from water but yours is from coal, better to put my solar panels in your area than in mine.

Producing power at home is quite personal, but producing it at a remote location is different. It would make sense to buy an acre of desert in California and invite people to erect their solar panels there, for a small fee. Or find investors and cover the area with solar, for a return on investment. Bigger systems benefit from economies of scale. Wholesale prices on PV panels and inverters are just the start. Solar/steam/turbines, with a large array of solar-tracking mirrors that superheat water to drive a turbine is pretty attractive, but only at a large scale.

Surely this is better financially than doing it under gray Seattle skies, 1 house at a time, right?

In fact, the power company here (Puget Sound Energy) offerers a "Green Power Program", where I pay a little more for my power (about a penny per Kwh) to do something similar. The money goes to pay for renewable energy production, but you can't really track dollars or Kwh very closely. It's way cheaper than installing a solar array on my roof, though.

So, while photovoltaic panels may be a great technology to invest in, it seems like there are lots of reasons that the roof of your house is not the ideal place to put that equipment.

So, when does solar at home make sense?

First, solar house design. In my climate, that means windows to the south and thermal mass to match, along with plenty of insulation and reducing air leaks.

Second, solar hot water is interesting. No complex electronics or batteries, and it only works close by, so no producing hot water in Arizona to use in Washington. There are plenty of downsides that I won't go in to here.

Third, when off-grid, local solar power can be part of the picture. But this is a lot more expensive and complex than a grid-tied system, and you probably still want a generator for backup when it's not sunny. Again, lots of complexity that I won't go in to here. RV and boat people have this pretty well figured out - go talk to them.

How to build a yurt platform - part 1

Yesterday I started working with a carpenter on the new yurt platform. We spent the day setting up batter boards and string lines to lay out the pier blocks. Here is the result:

There are 30 pier blocks. Each one will sit on a bed of gravel. My next step is to start digging some holes!

How to move a yurt platform

After taking the yurt down, we still had some daylight, so we started working on the platform, but it took all of the next day to finish taking it apart, and a Julie and I spent 1/2 of a 3rd day wrapping up. The platform was way more work than the yurt. Keep that in mind if you ever think of getting a yurt quick-and-easy structure. (It is possible to put them on the ground with no floor, but that's more temporary.)

Taking apart the platform was so hard that I wrote a question about it on the Home Improvement Stack Exchange. From that question:

Decking was 1 1/8" tongue-and-groove plywood, fastened with 3" Robertson (square-drive) screws. The deck was painted after installation, so some paint was in the screw heads. A regular cordless drill wasn't strong enough to turn these screws, but an combination drill / impact-driver was able to do it. However, maybe 1 in 10 screws had their drive heads stripped instead. Too much friction / too much torque. We used a Sawzall to cut those screws out. Went through 4 Sawzall blades.

Framing was 4" x 6" joists on 4" x 4" posts on concrete piers. Most lumber was pressure-treated, but about 1/3 of the joists were not. Beam-to-post caps were nailed in to the joists and posts, 3 nails on each side. We spent a lot of time hammering a Cat's Paw under the nail heads, and then prying them out.

Insulation was 4' x 8' sheets of 2"-thick foil-faced foam board, between the joists, secured with 1/2" x 1" lath strips, which were fastened with 2" screws. To be able to get the Sawzall in to place, we crawled around in the dirt under the yurt to remove the foam. These screws were also hard to remove, and sometimes we had to break the lath instead.

I was tired after each day of work, but the 3rd day left me deeply exhausted. The work of loading 30 concrete footing blocks kicked my butt. Many of them I had to carry up hill. I'm guessing they weighed 50 lbs each, so we put 1500 lbs of concrete in the back of the truck. Maybe more.

My new yurt location is pretty flat, so I don't necessarily need the posts. I can just lay the joists directly in to the brackets on the concrete footer blocks. However, I'm considering using the posts anyway, just cut short (6"? 12"?).  It would be easier to crawl under the yurt with a little more space. Getting all 30 blocks in just the right location, with the ground under each block perfectly flat, is tricky. Making all the blocks be exactly the same height is even harder, but cutting posts to the same length is easier. Also, I already have all the posts and brackets I would need. Downsides are more fastening required and the need for steps up in to the yurt.

How to move a yurt

Last week we took apart the yurt. I tried to find information online about how to do that, and couldn't find much. I wish I could have done time-lapse photography of the operation, but I don't really know how. So, here's a blog post that I hope someone will find useful when they want to do the same thing.

This yurt is a 30' model, which is as big as they get. That's 700 sq. ft. It seems like there's a practical limit at that size. It was made by Pacific Yurts in 2006. I wrote the company and they sent me a PDF of the construction manual, and said "just follow it backwards". That was helpful, but we still had to figure out a lot as we went.

It was built on a hillside. That meant that reaching some parts of the outside wall was really hard; luckily we had a long extension ladder.

1. Scaffolding

While the walls are only ~7' high on the perimeter, the center is more like 14' up. The instructions recommend scaffolding, so we rented some from an equipment rental place that was close by. We had a choice of 7'-long or 10'-long platforms. 10' would be too long; get the 7'. Each unit gets you 5' up, so two units give you a 10'-high platform, as recommended by the manual. Any taller wouldn't fit, and any shorter wouldn't be enough to manipulate the canvas cover.

We rented the scaffolding for a week for $55. That night I got sick with a stomach bug, and the equipment sat idle for 5 days. Finally I felt well enough to work and we assembled the troops. I called all my friends & a couple professional builders, and ended up with 4 adults: A pro, a young woman who helps in Reid's nature class, wife Julie, and myself. Reid was also with us.

2. Bubble.

There's a plastic dome in the middle of the roof, called the bubble. Under it is a small fly screen, which came off easily. After removing the bubble we tied on a 1/4" rope and slid it down the roof, using the rope to slow the slide. The instructions said to put it on a piece of cardboard, but we just flipped it upside-down. It was easy.

3. Walls.


The wall canvas hangs on small hooks from a string at the edge of the roof canvas. At the bottom it is held in place by a screw every couple feet. The screws came out first, then we unhooked and removed the walls. On the downhill side of the yurt this was tricky, and the long extension ladder was the only way were able to do this. I'm grateful that the guy I hired happened to bring one. We folded up the wall panels and loaded them in to the truck.

There were at least a dozen yellowjacket nests under the edge of the roof at the top of the wall. Luckily we were doing this in December, and all they were all in their winter homes underground.

Under the wall canvas was a foil-faced insulation layer, held in place by zip ties at the top. We clipped them off and the insulation panels dropped away. We folded & loaded these, too.

At this point, the outer walls were only lattice, which looked pretty cool. I could imagine using something like that in Hawaii in a remote area. Lots of airflow.

4. Roof material

The roof is a layer of heavy canvas, over a layer of foiled-faced insulation, over a light cloth layer, resting on a wooden frame.

A friend who has the same yurt said that getting the canvas on to the roof was the hardest part of the job. Two of us stood on the scaffolding, which put the compression ring at waist height. We grabbed the canvas on one side and started pulling, bunching it up in front of us. When it was all gathered, we passed it over our heads, and then pushed. The two on the ground pulled, and the whole thing slid to the ground in a clump. We spread the whole thing out flat (in the nearby septic drain field), folded it in half, then folded the sides in until they met, and then folded in half again. This clump we hauled to the truck. This step would have been hard with only 3 adults, and extremely difficult with only 2.

Meanwhile the light insulation layer was trying to lift off in the breeze. It is made of a series of wedge-shaped panels, taped together with aluminum tape, and they were trying to separate. Power lines from the street passed right over the yurt, and they threatened to touch. The wires are insulated, but I was still wary. Luckily we were able to move the insulation away from the power lines quickly. We rolled the insulation up, folded it in half, and loaded it in the truck.

The light cloth cover was easy to bundle up and carry away.

5. Rafters


The radial rafter system is clever. One end has a metal pin that fits in to a hole in the compression ring. The other end has a sawn slot, which fits around the tension wire at the perimeter. A screw in the end of each rafter helps make sure the wire doesn't pop out in a windstorm.

Before removing any rafters, we had to remove the "safety cable" that runs through some holes in the rafters. There are actually 4 holes in each rafter, to allow for an upgraded "snow and wind kit" but this yurt didn't have that element. The wire is held tight with cable clamps. My plain old step ladder was not quite high enough to reach this; make sure you can reach with your ladder. Once the clamps were removed, we unrove the cable and coiled it up.

To pull a rafter out, I stood with my back to the lattice wall and grabbed the rafter over my head. I pushed out on the wall with my body, while pushing the rafter inwards with my hand. When the wire was clear, I then pulled the rafter outwards. Another person in the scaffolding held the other end of the rafter to help pull the pin end out of the compression ring. I had this idea that I would remove every 8th rafter, then every 4th, then every 2nd, to keep the tension even. This was not helpful. I should have just removed every other one to start.

As the number of rafters decreases, the tension cable gets a little lose, and the roof system gets floppy. This is a risky part of the process. I wore a hard hat, and did hit myself in the head with a rafter once. No kids allowed at this point.

Eventually we got down to 3 rafters. I unhooked one, and had a helper hold it in place. Then I unhooked another & gave it to another helper. Then I unhooked the 3rd, and held it myself. The 4th adult was still on the scaffolding, and held the compression ring. We then lowered the whole thing until the ring was on the platform. We unhooked the rafters and stowed them away.

The rafters are quite long (maybe 15'), and would not fit in the back of my truck, even though it's a full-size truck with a long (8') bed. The guy I hired had a compact truck (Toyota Tacoma) with a lumber rack, so we used that. But before loading, we took down the lattice walls so they wouldn't be in the way.

We got to this point in about 2 hours; way faster than I expected.

6. Walls


The walls are a relatively light lattice framework, riveted at every crossing. One section covers approximately 3/4 of the area, and one covers 1/4 of the area. The doors go in between the two sections of lattice. They are bolted to the door frames and attached to the platform with metal brackets. The tension cable lays in the crotches at the top of the lattice; we removed the tension cable at this point.

We removed all the fasteners, then popped out the smaller lattice section. It's quite unwieldy. We compressed the lattice, which is tricky because it wants to bend instead of compress. I wonder if a brand new lattice moves more easily? It was noisy, and we may have snapped some of the wood. It's also really easy to get fingers pinched as you do this. (Hint: the more you compress the lattice, the easier it is to roll it up. So, compress all the way!)

The large lattice section was even harder to manipulate. For a while we left it standing in a cylinder on the platform. The wind blew it over the side and down the hill. This was a bad idea. We should have compressed it all the way and secured it somehow.

Once the lattice is down, the doors are not very stable. They are held in place with a pair of screws in to the platform. Get these screws out and lay the doors down right away.

At this point the yurt was completely disassembled. We hauled everything to my garage to keep it out of the weather until the new platform is ready.

Next time: taking apart the platform.