10 Myths about wofati, and Facts

I post this because I think there have to be at least 10 misunderstandings, rookie mistakes, or other things that could be clarified.  I think I understand the wofati now, but then again a few months ago I thought I understood the wofati, then found out I had some aspects completely wrong.  And about six months before that I was _sure_ I knew what a wofati was, etc.

So, here's one (and I hope this is really really accurate now):

MYTH: it's dug into the side of a hill

TRUTH: It's mostly above ground.  The "earth-integrated" thing means that you pile dirt on top of the roof, and that dirt has a clear path for every drop of rain that falls on it to get to the ground.  It may look somewhat like an underground house, therefore, and has the advantage of being invisible to the alien invaders' satellites, but it is built above the ground.  You can make it on a fairly gentle slope and you get the dirt from a nearby spot.

Here is one  question, I'll post more later, I had posted about wofatis, and I'll gather the answers I've gotten from people who've acutally seen them later when I have time:


does it have to be on a hill or on a slope?  if a slope, maybe "upslope" and "downslope" would be clearer?

Is this like the 10 types of people in the world, those that understand binary, and those that don't?  

Truth: a wofati can be built on a slope or on flat land-the slope is not necessary.

Building by digging sub-grade into a slope is more of a Mike Oehler, "The $50 and up underground house" idea. The wofati per Paul is 80% Mike Oehler design principles, but digging sub-grade into the slope is one that is not included. It is still earth-integrated (which Oehler said would. be a better term for his design as well), in that soil is bermed against the walls and added to the roof.

Mark Tudor wrote:Truth: a wofati can be built on a slope or on flat land-the slope is not necessary.

Building by digging sub-grade into a slope is more of a Mike Oehler, "The $50 and up underground house" idea. The wofati per Paul is 80% Mike Oehler design principles, but digging sub-grade into the slope is one that is not included. It is still earth-integrated (which Oehler said would. be a better term for his design as well), in that soil is bermed against the walls and added to the roof.

Mike didn't always dog into a slope either.  His book includes an example that I believe he called a "flat earth house". I don't remember for certain if that was the name,  but he gave an example with plans for building it.

I always thought the WOFATI Design was a little better...at least for me...because my soil is very thin here, at least where I want to put my home. This particular location has a great view, but being on a big hill, it gets slammed with wind. It does not seem like a big deal, but me and my wife hate it. On a winter day it literally can take your breath away.

We have a WOFATI plan that brings natural light from (2) sources into every room, gives us our view. but the WOFATI itself would keep the wind at bay.

That design is small however, so our plan is to stay in this Tiny House for 7 more years, then when it is just me, my wife and the youngest child, build the WOFATI and live there, renting this Tiny House out.

Mark Tudor wrote:Truth: a wofati can be built on a slope or on flat land-the slope is not necessary.

Building by digging sub-grade into a slope is more of a Mike Oehler, "The $50 and up underground house" idea. The wofati per Paul is 80% Mike Oehler design principles, but digging sub-grade into the slope is one that is not included. It is still earth-integrated (which Oehler said would. be a better term for his design as well), in that soil is bermed against the walls and added to the roof.

I have discussed complications of flatland wofatis with Paul in the past. I think there are two main issues:

1) On flat ground (like where I live) you have to dig a huge hole in the ground somewhere on the property in order to be able to cover the structure with enough material. Less earth moving is required on a slope.

2) This is a big one. A wofati is a pole structure. Including its foundation. And it's made of untreated wood. It is much harder to keep those poles dry on flat ground than it is on sloped ground.

Some will disagree with me here, but it's for that reason, Shawn, that I suggest rammed-earth pillars as an option for flat land or otherwise lumberless wofati.

No, I have not yet had the opportunity to put it into practice, but if there's no appropriate lumber around, and the right types of sand, soil, and clay can be found, it might prove not only more structurally sound, but cheaper than hauling appropriate lumber to the site.

As to where to get the dirt cover, isn't that what ponds and earthworks are for?

-CK

This is site specific to me I know, but the area I want to build a home experiences incredibe winds, so we want to go underground to get the great view,, but shield us from the wind, and a WOFATI is a way to do just that. But my soil is VERY thin, and flat. PERFECT!

To ensure drainage, I would scrape the soil off the bedrock, then pin the posts to the bedrock with bored pins. That will ensure the ultimate foundation. Then I would bring in screened rock, probably 2 inch minus, and level where the house will be. This will enable water to drain well away, and from under the house.

To reduce overall costs, and to make the building more managable, I would reduce the overall thickness of the earth on top of the house to only a foot, but ensure thermal protection via insulation. I would also use sawn lumber on edge, and use steel roofing on two layers to hold the soil and be a primary impedence to water. Steel roofing is cheap, so two layers adds little to what it brings to the house in terms of water impedence, strength, and ease of installation.

All other aspects of the WOFATI I would do normally, like ensuring it was facing south, passive heat, etc, but would have custom doors made for the windward (Northeast) side of the house. Here, it is not uncommon to have wind gusts blow in the doors, so my doors on this side would open outward. In that way the wind would blow it tighter against the door jam, and not blow them open.

I believe Mike's flat ground house (the "garden house" I think?) was definitely on flat land, but was dug down several feet below grade which made it easy to get the soil for the roof and the top of the walls. I'm considering this for my own site which is overall very flat, like 1-2% grade in the "steep" spots. Dig down 4 feet, use that soil on the roof and sides, and where the insulated umbrella ends, dig a trench that goes around the space and drains away to the lowest point. Fill trench with gravel and cover with landscape fabric then dirt like a french drain. The umbrella would terminate into the trench and would be at the interior floor height. This would put the draining water around 20 feet away from the walls.

As my site doesn't have much in the way of duff, I'm considering extruded polystyrene in 4'x8' sheets as the insulation layer, which I believe is the form that ants won't devour and is what was used in the PAHS version? So poly sheet on the roof, then 2-4" of insulated sheeting, then the second poly sheet, followed by 12-18" of soil to plant shallow-rooted growies on.

The 1/3 roof slope makes sense for excellent drainage, but seems a problem for the soil runoff. Mike mentions 1/4 being acceptable and 1/5 risking leaks as the water could back up. 1/4 seems fair for drainage and soil retention and also not creating overly tall single story spaces. For example, considering a 4 foot excavation for soil in a flat area, and the room being 16 feet wide, you could start the ceiling at 7-8 feet high and end at 11-12 feet high which would be 7-8 feet above grade if you didn't excavate further out for a sunken patio space.

A person could also probably replace the wood shoring with earthbags, so long as they were shaped and placed to create supporting arches that push back into the earth berms. Logs on top for the roof could be supported by these, especially if you pour a bond beam on top. Filling/placing/pounding the bags and then adding an interior finish coat adds a decent amount of time but could look quite nice compared to bare/painted dimentional lumber or raw logs.