Jonker Wofati

Prep-

I own about 9 acres of land in Missouri. I bought a trailer to put on the property for my family of 7, now 8. 2 Years ago, we built a 30x16 addition to add some room and a hallway attaching it to the trailer.

Our intention was to build the rest of our home, a piece/section at a time, removing the trailer once enough of the house was completed.

We've been considering Straw bale, cord wood and last year I learned about Wofati.

We've got the wood and the dirt and the time and the land, so we are looking towards a Wofati hybrid.

Rather than burying the posts, I want to dig a hole, place to layers of rammed earth tires in it, so it will raise about 12 inches above the surface and use concrete to finish off the pier (rammed earth basically becomes infill), then mount the logs as posts on the piers.

On the shell, before the first tarp, instead of the 10 layers of newspaper. I am thinking of using a layer of papercrete to fill in and smooth out the shell.

I am wanting to use compacted road gravel for the interior flooring instead of dirt or concrete. I am not completely sold on the underground/Ohler house, dirt/plastic/carpet idea. (FYI, the first few inches is straight road gravel, then you run the next layer through a screen to use a smaller material for a couple inches, then reducing the screen size until you get down to fine powder at the surface)

I want to make a rocket stove, using the floor as the Mass.

Some obstacles:

Right now, I've got the trailer and the addition in the way. I plan on building around/integrating the addition. I plan on placing the posts and the roof in a way to pull the trailer out through an opening in the wall.

Some Questions:

What would be the best way (cost and durability) to attach the posts to the piers?

I am looking at incorporating a shipping container into the structure to function as a storage/hallway/storm shelter inside the building.

What would be an option for building the Wofati a section at a time? Or will it have to be built all areas at once?

I am working on some initial plans and budgets right now.

Logan Jonker wrote:Prep-

I own about 9 acres of land in Missouri. I bought a trailer to put on the property for my family of 7, now 8. 2 Years ago, we built a 30x16 addition to add some room and a hallway attaching it to the trailer.

Our intention was to build the rest of our home, a piece/section at a time, removing the trailer once enough of the house was completed.

We've been considering Straw bale, cord wood and last year I learned about Wofati.

We've got the wood and the dirt and the time and the land, so we are looking towards a Wofati hybrid.

Sounds fun. First some observations:
1) Wofati as compared to straw bale or cord wood works differently. Straw bale especially is a high insulation home, but wofati is a high mass home. I personally, would go high mass because I also like fresh air and high insulation homes just keep the air warm.
2) You have already chosen a site. A wofati is site specific, designed to be on the side of a hill, if you are now sited somewhere flat that would be one way your home would differ from the stock wofati... however, the wofati has only been built once and the design will be in a state of flux for some time, so take the good points and start there.
3) there are two other methods of building that may suit as well, cob and earth bag. Earth bag has been used along with shipping containers by others and seems to work well. See: Containers and earthbag In your case the trailer might fill the part of the container as they have the kitchen/bathroom in it and that would be the main use for your trailer.

I think the wofati is a great idea and am not trying to steer you away from it. More I am thinking the more you research all building methods, the better prepared you will be to adapt the wofati principles to your situation. A general understanding of PAHS ideas would help too.

Some obstacles:

Right now, I've got the trailer and the addition in the way. I plan on building around/integrating the addition. I plan on placing the posts and the roof in a way to pull the trailer out through an opening in the wall.

Some Questions:

What would be the best way (cost and durability) to attach the posts to the piers?

I am looking at incorporating a shipping container into the structure to function as a storage/hallway/storm shelter inside the building.

What would be an option for building the Wofati a section at a time? Or will it have to be built all areas at once?

I am working on some initial plans and budgets right now.

Shipping container? How big are you planning on? Also the wofati is bermed/buried, is the container expected to take any of the weight of the earth? There are many warnings not to do this because they crush when buried. So long as it is just inside the structure it should be fine. As the wofati is post and beamish, removing a trailer and adding a container just means building high enough. Building a removable wall section? just a 2x4 frame with skin. A few lag bolts to attach and remove... as few as 4. After you don't need a removable section it can be made more permanent.

With regard to the structure you already have, how are you expecting to incorporate that? Is it stick built? Will it be completely encased, or will it support part of the earth berm? Or will it be outside the wofati part of things? If it is outside the wofati part of things, there will be two kinds of heating needs. An insulated frame part will be relying on the air temperature to feel warm, but the wofati part will be relying on radiated heat from mass and it's air temp will be lower. This may make for some interesting design considerations. Unless the frame part is dirt floor. (mass connected)

The idea of a mass heated building is to keep the people warm and not the air, so the air temperature needs to be less than in most of todays stick built homes to feel comfortable. Comfort is not easy to measure. A person in a room with an air temp of 75F may still feel cold in front of a window where the outside temperature is -40F because their body is radiating through the window to a cold surface and so the heat is not being radiated back. Heated mass radiates heat towards the people who feel warm even though the air temperature may be 65F. So in a wofati there should be mass facing most sides of the occupants. In fact the original had windows on the uphill side and across the court yard there was a wall... light coloured so that it would reflect radiated heat back into the dwelling. I think the wofati is supposed to do that too. So you need to know why you are including whatever parts of the wofati idea you plan to use or it may seem not to work at all.

This leads into the whole idea of building part at a time. I have been spending some time thinking about this and even started a thread about it. Basically I think that anything built to be added to will be sub-optimal until the addition is built. Whatever wall is left unbermed will work less well at heating than the rest, whatever part of the umbrella is left unfinished will affect the whole mass's ability to store heat. The one way around that is to build more than one separate wafati close together and then connect them. So instead of having a whole wall in common, only have a door in common. This would mean setting up heat in each... maybe not good. Making two wofati next to each other then clearing the earth between them to add a middle section could work. The idea of wofati is that it is cheap to build and so the whole can be built together. The cost will go up if it is done in parts.... but then you can spread the effort over time as well as the cost.

Some drawing of the layout you have now and what you would add would help. I don't know if ascii art would work here as the font is not fixed width.

Thanks for the response: a couple more bits-

Our land is flat, so we'd be doing a more of a hybrid or Wofati and Ohler's flat land design. The reason I want Wofati is because of we don't have the straw or $3 a bale (+) for straw and I am a little undecided on the cord wood, traditional build- might incorporate the Cord/Bales on the exterior walls that aren't bermed (not sure if that is the correct term for the wofati design of the dirt on the walls where the roof meets the ground)

The other aspect of the hybrid may be that I don't use the full 32 inches of earth on the roof.

Shipping Container: I was looking at having it run North to South like a spine through the structure, so maybe a 40 foot. There are 8 of us, plus my in-laws, plus if we have any guests. We've been here 3 years without a storm shelter so incorporating it would add some peace of mind. Yes, I was thinking of having it partially supporting some of the weight of the roof. We wouldn't be replacing the trailer with the container, though. I had not heard of them getting crushed- even with just 2 feet of earth above it? Might have to look at some other options- just don't have 6 grand for a 4 person storm shelter.

Stick Built Addition- It was designed to go two stories- right now it has a flat roof and is single story. It should support the wofati roof, But I plan on extending some of the wofati over it, so It would support all that weight.

Heating- Out addition is insulated well, not much temp change- Our Trailer leaks like a sieve. It is a repo, bad condition and the previous owner had done a number on it. It's OK for now, but not the long term and apparently it may have come from the south as there is no sheeting between the framing and the exterior metal covering. I assume the overall Wofati design doesn't need heating and cooling with the Annualized Thermal Inertia, but If I cut back , I can manage it rocket technology and natural cooling.

The part at a time would be helpful to build enough, yank out the trailer to free up construction area and then continue building.

Got to Go- I'll add more this weekend.

-Logan

Logan Jonker wrote:Thanks for the response: a couple more bits-

Our land is flat, so we'd be doing a more of a hybrid or Wofati and Ohler's flat land design. The reason I want Wofati is because of we don't have the straw or $3 a bale (+) for straw and I am a little undecided on the cord wood, traditional build- might incorporate the Cord/Bales on the exterior walls that aren't bermed (not sure if that is the correct term for the wofati design of the dirt on the walls where the roof meets the ground)

The other aspect of the hybrid may be that I don't use the full 32 inches of earth on the roof.

Flat land does change things. It sounds like the reason for the wofati-ness is cost (not a bad reason). Generally what you do is use logs to make an ugly/quick log house and then put dirt against it and over it with some vapor barrier in between and then more vapor barrier/insulation and more dirt. But also, there is a hill behind the windows. Very few people talk about this or it's purpose. I think (I don't know if I am right or wrong) that this wall aside from providing a patio area and helping with drainage also reflects heat that is radiated through the windows from inside the dwelling back towards the dwelling... hopefully back through the windows. I don't remember for sure, but I think the hill version would be built on the north side so that the sun can still shine in the windows from uphill. You may want to therefore build a wall about 10 feet away (cob maybe?) which will not only reflect heat but also make a patio that may be comfortable later in the season. If you berm that wall or not may or not matter. Anyway, go for it, should be do-able.

Shipping Container: I was looking at having it run North to South like a spine through the structure, so maybe a 40 foot. There are 8 of us, plus my in-laws, plus if we have any guests. We've been here 3 years without a storm shelter so incorporating it would add some peace of mind. Yes, I was thinking of having it partially supporting some of the weight of the roof. We wouldn't be replacing the trailer with the container, though. I had not heard of them getting crushed- even with just 2 feet of earth above it? Might have to look at some other options- just don't have 6 grand for a 4 person storm shelter.

OK, so you are going to put doors in the middle then? It is hard for me to think in terms of a storm shelter. I have not ever lived in an area that has a need for one so I will just take your word. It sounds like the container needs to be in place before building that part of the building. I don't know what kind of weight it would handle, I guess some people thought they would use them as a bomb shelter (just made NSA's list?) and buried them down a ways. Using the berm will be storm shelter too, adding the wall (as above) with a berm behind it may help as well. A hill is naturally storm resistant and if you make your dwelling hill shaped there will be no flat surfaces for wind to grab.

Stick Built Addition- It was designed to go two stories- right now it has a flat roof and is single story. It should support the wofati roof, But I plan on extending some of the wofati over it, so It would support all that weight.

I'm not an engineer, so I really can't comment.

Heating- Out addition is insulated well, not much temp change- Our Trailer leaks like a sieve. It is a repo, bad condition and the previous owner had done a number on it. It's OK for now, but not the long term and apparently it may have come from the south as there is no sheeting between the framing and the exterior metal covering. I assume the overall Wofati design doesn't need heating and cooling with the Annualized Thermal Inertia, but If I cut back , I can manage it rocket technology and natural cooling.

The part at a time would be helpful to build enough, yank out the trailer to free up construction area and then continue building.

The trailer provides kitchen and bathroom till you build replacements then pull it out. That was my thought for my build too, but I would leave the trailer outside or in a barn. In my case I am thinking RV, you may have a mobile home? I want to go wood heat/cooking in the long run... my hope is to be able to get by with just enough wood to cook and then harvest the exhaust for mass heating.

BTW, part of using Annualized Thermal Inertia, is learning to live with some temperature swing through the seasons. Acclimatizing the body to live cooler or warmer... dressing warmer when needed. If you have family who expect 72F year round, they will not be happy without heat. My thoughts on this are that much of the home can cycle through the season, but that there should be a main room that has a warm mass that people can sit around to eat and or relax. A warm stone put in the bed a half hour before use will get it warm and the body will keep it that way if the quilt is thick enough. I guess what I am saying is that there is a life style change. Be prepared for it. I am looking forward to it and the kids are too. We will see what my wife thinks as we progress, she claims support, but I will have to make sure she is comfortable more than anyone else.

Thanks for the Response-

Storm Shelter- Are you familiar with the F5 tornado that hit Joplin, Mo in 2011? That's an hour south of us- I've actually lived within an hour of 3 different F5's in my life and several smaller storms. The Wofati design does offer the natural hill protection that resists wind damage. Oehler comments in his book about the fallout shelter aspect of his designs.

My kids are a bit nervous during storm season- Having a shelter within the structure for safety would be nice. Our land doesn't offer the option for a simple cellar- the land is mostly sandy soil with a sandstone bedrock about 6-8 feet down, so when it rains, the water level rises, yet drains away very quickly. "Floating" the structure at the surface offers the best chance for natural building, but having a safe place within the safe place is necessary. As well as offering storage, I thought a Shipping container would be comparable to some other makeshift options I have heard about.

The trailer provides kitchen and bathroom till you build replacements then pull it out. That was my thought for my build too, but I would leave the trailer outside or in a barn. In my case I am thinking RV, you may have a mobile home? I want to go wood heat/cooking in the long run... my hope is to be able to get by with just enough wood to cook and then harvest the exhaust for mass heating.

My sentiments exactly- we are using a mobile home.

BTW, part of using Annualized Thermal Inertia, is learning to live with some temperature swing through the seasons. Acclimatizing the body to live cooler or warmer... dressing warmer when needed. If you have family who expect 72F year round, they will not be happy without heat. My thoughts on this are that much of the home can cycle through the season, but that there should be a main room that has a warm mass that people can sit around to eat and or relax. A warm stone put in the bed a half hour before use will get it warm and the body will keep it that way if the quilt is thick enough. I guess what I am saying is that there is a life style change. Be prepared for it. I am looking forward to it and the kids are too. We will see what my wife thinks as we progress, she claims support, but I will have to make sure she is comfortable more than anyone else.

We are learning to deal with the temp shift as it is now, but having insulation from the natural design will help. Having just the 3 inches of insulation in our addition makes it so much more comfortable during weather shifts and we compensate, more clothes, less clothes, so with this new structure, I anticipate minimal heating and cooling will be needed.

Logan Jonker wrote:Thanks for the Response-

Storm Shelter- Are you familiar with the F5 tornado that hit Joplin, Mo in 2011? That's an hour south of us- I've actually lived within an hour of 3 different F5's in my life and several smaller storms. The Wofati design does offer the natural hill protection that resists wind damage. Oehler comments in his book about the fallout shelter aspect of his designs.

My kids are a bit nervous during storm season- Having a shelter within the structure for safety would be nice. Our land doesn't offer the option for a simple cellar- the land is mostly sandy soil with a sandstone bedrock about 6-8 feet down, so when it rains, the water level rises, yet drains away very quickly. "Floating" the structure at the surface offers the best chance for natural building, but having a safe place within the safe place is necessary. As well as offering storage, I thought a Shipping container would be comparable to some other makeshift options I have heard about.

"familiar" for me, is video clips on a small screen. I would suggest you and your family have a different feeling having been that close. My thought (and you may have thought this already) is that if a tornado is able to get through an earth berm roof, it might very well be able to lift a container out as well. I think in your place I would also put some anchoring in place. Some chain or cable anchored to the bedrock and the container should do it. I don't know what size to recommend, but you are probably closer to places that have the info than I am anyway.

We are learning to deal with the temp shift as it is now, but having insulation from the natural design will help. Having just the 3 inches of insulation in our addition makes it so much more comfortable during weather shifts and we compensate, more clothes, less clothes, so with this new structure, I anticipate minimal heating and cooling will be needed.

Now to find a container...

You could build an earthbag dome or a rounded curved berm facing south. Domes or a rounded berm man-made hill let the tornado pass over. Flat surfaces are what catch the wind and offer an area for the force to push and push over. You could dig out a long pond on the south side and use the dirt to fill the bags to make your shelter. Designed right you should have a nice home and a storm shelter that you can add onto a section at a time. You could look at this or many other sites like this to get an idea of what can be done. http://www.earthbagbuilding.com/articles/riceland.htm

Use your pond to raise extra food and provide double light to heat your home and grow your garden.

Good luck!

Jason Learned wrote:You could build an earthbag dome or a rounded curved berm facing south. Domes or a rounded berm man-made hill let the tornado pass over. Flat surfaces are what catch the wind and offer an area for the force to push and push over. You could dig out a long pond on the south side and use the dirt to fill the bags to make your shelter. Designed right you should have a nice home and a storm shelter that you can add onto a section at a time. You could look at this or many other sites like this to get an idea of what can be done. http://www.earthbagbuilding.com/articles/riceland.htm

Use your pond to raise extra food and provide double light to heat your home and grow your garden.

Good luck!

An interesting thing happened today while looking through lots of earthbag designs and projects. I noticed a lot of earthbag dome construction and so decided to look at one. Mainly because they all looked quite small. The story showed the building being built, complete with the smiling designer outside the finished building. Then there was a letter from someone who had gone to the site to see it a few years later, they sent a picture of an abandoned building with various plant life growing out of an obviously unlivable building. Failed Earthbag Dome. To be fair, there was also an analysis of why and what should have been done to prevent the skin failure, but.... I then looked very closely at the rest of the designs. What I saw:

1) Most domes were being built in very dry places. Very little visible vegetation.
2) The pictures were all "just finished". There seemed to be none of the "we've lived here for years" pictures (like at least furnished, but lots of nick-knacks is better)
3) The earth bag homes with a roof often had pictures (with furniture, nick-knacks... signs of collected life) that appeared to have been lived in for some time.
4) Bermed or buried earthbag building had a vapor barrier right next to the earthbags even before the outside insulation (not the way I would do things anyway).
5) Any of the buried earthbag buildings did not use an earthbag dome to support earth, they used post and beam for that, though it seemed to be ok to use earthbag for the walls (which were curved in any that actually showed construction pictures).
6) The earthbag domes seem overly high to be buried. That is the amount of digging required and the space above aquifers is more than other designs.

My conclusion is that earthbags are well suited to vertical walls. Maybe not so great for a roof. Also, earthbags need to be kept dry, just like cob. I am looking into all of these ideas (cob, earthbag, wofati) for my own project. Wofati and earthbag both look to be reasonably fast. Cob looks slower, but has good history of working well in this climate (100s of years anyway). I will note that the closest building style to wofati, a pit house, while used by some of the aboriginals a few 100 miles away, was/is not used in this area even though the same people occupy both areas. The pit houses seem to start about 100 mile from the ocean. Those who live close to the ocean live in Long Houses (or big houses, as much as 150 feet long) which are also used by the farther inland people during the summer.

An interesting thing happened today while looking through lots of earthbag designs and projects. I noticed a lot of earthbag dome construction and so decided to look at one. Mainly because they all looked quite small. The story showed the building being built, complete with the smiling designer outside the finished building. Then there was a letter from someone who had gone to the site to see it a few years later, they sent a picture of an abandoned building with various plant life growing out of an obviously unlivable building.

I noticed that too, but thought it could be fixed. That failed building was in the Philippines, which is a wet humid place-- so not all are in dry places. There are always the Earthship designs. They would have to be modified for a storm shelter, but could be built into a berm. Whatever you choose I am sure you will find something that will work for your situation.

Logan, it sounds very exciting and I wish you the best of luck. I can add very little to Len's excellent comments; I simply don't have the experience that he has. But from all the books, papers and websites I've seen - everything he said sounds right. And amazingly comprehensive -- kudos to you, Len. I will, however, add just a couple opinions for your consideration and Len's.

1) I wouldn't apply the WOFATI principles too strictly when it comes to "the north-facing slope". Though that is probably the most ideal layout, it is not the only one. Your plans seem to comply with the W_FATI perfectly. It is only the "O" - or classic Oehler design that requires some small adjustments. But I would call your attention to Mike's book. He included an entire section on "Flat Land" designs - suggesting 6 different approaches that not only comply to the W_FATI goals, but will stand up to tornadoes as well or better than his classic design. Also John Hait's book deals almost exclusively with flat land designs.

2) I agree with Len regarding earthbags, and I'd be a little concerned about the earthship tires as well. Here's why: The amount of weight that the wofati dirt roof puts on the structure is huge! And as I recall, MO is not devoid of snow in the winter. Unless you're a structural engineer and can calculate the compressive, tensile and sheer forces that your structure will require - assuming that the those coefficients for earthbags and tires are known and well documented, and that you can control the variables that inevitable occur in dirt or used tires - then I'd be concerned with structural failure. The W in wofati is for wood; and I think for a good reason. With the possible exception of concrete, there is no better understood or well documented material than wood when it comes to how it will behave under extreme conditions. Wood may actually have a slight advantage over concrete (great in compression, shitty in tension) and earthbags, and possibly tires rammed with dirt. In high winds - especially variable gusts - especially variable directions (i.e. tornadoes) WOOD BENDS just a little!! Concrete doesn't. Earthbags don't. And - though rubber tires may bend, I don't know if rammed tires will?

Logan, even if you're very confident with using earthbags or rammed tires under the huge weight of a wofati roof -- will the building inspector be?

3) I am actually a huge fan of domes. In the natural world of permaculture - there is no stronger, more natural shape than the dome or arch. But only if we can control the load vectors at all times. Consider the egg: When pressed between your palms along it's length, it's almost impossible to crack. When pressed between your palms along it's width, failure occurs with minimal (human) effort. Now, consider an unborn chick; though weak and feeble, it's able to puncture the same egg shell FROM THE INSIDE. Conclusion: The shell of a dome will behave in a similar way. The gravitational force of the dirt and snow will vary at different locations of the dome. Either the dome must be designed for these standard variations OR you over-engineer the entire structure. But now - how about that pesky tornado? It places a whole new set of variables - changing constantly across the entire shell. Worst of all, the tornado can exert an upward or outward force; just like that little chick applying forces on the concave side of the dome.

Like I said, I love domes. And it could work ... even in a tornado. But that pesky building inspector mostly understands just IRC codes for stick-frame houses. If you're lucky, he'll have some appreciation and tolerance for Post & Beam. But the chances of him whipping out a code table with minimum requirements for an earthbag dome may be a stretch.

Jarrell, TX was hit by an F5 tornado in the 90's, and 26 people died, mostly on one street. A man I know, Gabrielle, was terrified of the possibility of getting hit by a tornado, so he dug a cellar hole directly in the middle of his concrete foundation house, and rocked it in with limestone. When the tornado came, his wife and son and the neighbor's wife and son went inside it and were about the only survivors in their neighborhood. Absolutely nothing was left of the homes, even some of the slabs were peeled up, as was 2' of topsoil and the the asphalt road.

That being said, why not use rock and a slipform to make a cellar that is intergrated into the house? Build it into a back wall and cover it with the earth berm.

Do you have rock on your property? Are there any farms in the area that have picked rocks out of the field that they might let you have?