Wofati build finally started

Hello everyone,

We started our build today on our Wofati!!!

Well kind of started lol.  After many drawings, reading and years of research were 3D printing our wofati timber frame and will be assembling soon.  Need to see my design to prove it.   Once that’s completed and the frost out of the ground we will start digging post holes and finish milling our lumber!

I’ll try my best to keep our build updated, please chim in any time with better ideas and such.

Please stay tuned for the model build and official ground braking!!!

Current details
Main frame footprint 48x32
Insulated umbrella extending 20ft in all directions
8x8 timber frame
Post 8ft on centre
Got tons of used plastic from farmers throwing out it’s like 10m or something will be able to put multiple layers on the wood layer and over the insulated thermal mass
4” insulation tappers down to 1” on the thermal envelope
Building on flat ground


First order of business after the model is built and plans or final in my head...

Drill holes for posts
Throw posts in holes
Plumbing and electrical chase brought in
Bring gravel in tamp level posts bring floor grade up to meet satisfaction lol
Finish framing
Shoreing on walls and roof
Back fill the wofati

Enjoy my journey
Finally able to give back from my experience here
Byron

Sorry not good at sketch up yet
I’ll try and include a more detailed draft of the plans soon

I just watched a wofati video and one thing Paul mentions is that he wished he pounded his vertical posts down when he set them in place.  All the weight of the earthen roof has caused some to settle.

Another thing he mentions is that wofatis are best on sloped land.  I can't remember if that was a deal breaker or if it just reduced the amount of dirt that needs to be moved around.

This will be a cool build to watch!!!

Yes thanks for that reminder about the pushing on the post with hoe if I remember correctly when Paul was saying.

Yep easier to move dirt uphill downhill onto the structure.  I’m digging a dug out no way around it it’s just going to be work.  Another detail is building the floor up above the grade of land in effort to keep dry during spring run off.

Cheers
Byron

Awesome, I'm glad you have it all thought through.  I don't know how many wofatis have been build outside of the lab so this will be neat.

Here’s the water shed direction off the structure.  I think I got it right.  No drop sees a edge and always away from the structure.

Window placement.  Note the front windows facing directly south for most amount of thermal gain.  Two rear windows for bedroom light, ventilation in summer and egress.   The windows facing the centre mass or 8 ft off the grade allowing the centre drainage off the front of the structure to continue downhill to the rear of the building passing under the windows.   This area will need particular attention to insulation and vapour detail when building.   These two high windows will allow for a pile of light into the structure from different angles at the same time allowing the rest of the thermal mass to remain beefy and continues.

Beam detail how I plan on my timber frame to be payed out very affective I’m thing fast and easy.  Dealing with the inward pressure on the structure and downward pressure.  

Please rip these apart and tell me what’s wrong!  

Cheers Byron

Correction on the beam detail drawing left beam connection is the one I’m aiming for max contact for inward and down ward pressure.

That left edge joint configuration looks very solid. The central ones (not to scale I hope) need to have the notches in the beams as shallow as possible so you don't weaken the beams and have them split at the inside corner of the notch from the extreme downward load. If you are using roundwood, just flattening the bottoms of the beams to give 4-6" width of flat bearing surface should do it. If the beams are going to be squared, I would make the notches in the beam bottoms no more than an inch or so, just enough to positively place them at assembly. Once loaded, they will never slip in a million years.

The best central joint detail would have the beams resting on a ledge on the post, and lapping over the top to join them, similar to the edge joint; but this is distinctly more work than simply flattening the tops of the posts. I would do it myself if I were building such a structure. Flatten the post tops at the right level, then notch each side say 2" x 2", and notch the beams to fit. The beam cutting is no more complex than before.

Yes ok great insight!

I’m doing 8x8 timbers.  I’ll adjust the beam to 7” thick over the post at the moment it’s 4”.  I understand know and should known that.  So easy to make adjustments know on paper lol.  I guess I could even leave it a full 8 and set it on top with couple log anchors securing it.  Then no structure on the beam will be comprised.

Trying to wrap my head around the connecting beam, possible for a diagram? I’ll reread and rethink it.  

Thanks so much
Byron

Ok got it that’s strong as can be thanks for the detail!

I’ll be using 8x8 posts. 8ft in centre.
With 8x8 girders. From the main frame.
So each connection lap will be 4”x8” making for a great contact.  Then of course pinned together.
Revised sketch of post details

Err I did it again the right joint is wrong lol

Tell me to turn right I’ll go left everytime lol

The south wall is at the top of the plan view, right? That is ideal for light capture and seasonal heating, but the back windows are not. Obviously you need windows in the bedrooms for light and egress, but I think this particular configuration will lose much more heat than the lighting benefit warrants. There will be a bit of winter morning sun in one bedroom and a bit of afternoon sun in the other, but windows high in the walls will maximize heat loss while giving minimal solar gain.Those windows don't benefit the lighting of the main space, either.

I think you would get just as good lighting from putting the windows at the outside corners of the bedrooms, facing north and east or west respectively, with small gables at each corner to shed the water off to the sides. This would have much less in the way of complex waterproofing joinery in the roof and sidewalls (no sidewalls at all), and less exposure of roof edges to lose heat.

How tall are you thinking of making the south wall? If the space is 16' deep to the back of the main space, a 21' south ceiling would let winter sun in to hit up to maybe 6' high at most of the back wall, so the earth mass in the center of the volume will not be fully useful for thermal storage. With the envelope simplified to a rectangle instead of a U, you could put a masonry and/or cob mass in a good heat capture and storage position while keeping it only around 4' high, and be able to use the top of it for something... lounge, plants,...

A rectangle would have more roof area, but considerably less sidewall area to waterproof and fortify.

I do see the feature of your roof layout having no slope longer than 16' or so from top to lower edge, so slope can be maintained without excessive height. I can think of ways to keep that feature with a rectangle, like melding a full hip roof with the south-facing shed so water drains east, west and north from the central ridge. The bedroom corners would be thus placed to easily divert water from windows at the corners to either side. This would give a large central area of high ceiling, which could be used for a balcony over a storage area or something.

Yes, good joint details

It looks like you're in Canada... seriously cold climate? What is the subsoil like? Where is the water table? If it is not extremely well drained, I think you will have serious problems with groundwater unless you can trench away from the sides and the postholes to drain.

Subsoil average temperature is close to the average annual air temperature no matter where you are, and I would have some concern in Canada about trying to heat up that mass under the floor. It will always conduct downward to some degree, more if the soil is clayey, less if it is sandy.

Yes the top of the plan is due south.

The front wall was going to be 12ft.  Sloping down to 8ft over the 16ft run.   According to my calculations winter sun will hit the back wall the shortest day.  As the sun is so low on the horizon, but we only get 4 hrs of it on the shortest day.  I’ll really benefit from fall and spring gains as the days get longer in feb through till end of May solar gain would be a premium then aug till October a lot of gain again.  The sun is right over top in the summer, that’s why the detail to the rear of the structure with high windows.

This gives me lots to chew on. So wonderful.

More details about my build is I’m in the far north Yukon Canada.  We’re very dry little snow long cold dark winters.  Shortest day 4hrs winters solstice.  Summer nearly 24 hours of light hot and dry.

I here you on the middle windows in my defence they won’t be very big like I did in my shop I’ll attach a pic.    I placed seven around to let in light high and low.

The bedroom windows were only going to be as big a necessary for proper egress.  Also special order quad pane.  Insulated bearm up to the bottom of the window here.  Was what I was thinking.  Any exposed surface would be detailed and insulated to the highest degree not really on a budget for those details pull out all the strings best thermal glazing and insulation for these parts.

In the summer the sun rises in the north and sets in the north compass bearing would be rises at 20degrees say and sets at 340 degrees.  During the day the sun would literally poor into the house through those little windows in the roof.  

Insulation would be 4” of foam over the structure and continue out 8-10 feet then down to 3” for 4-6 ft then 1” remaining out to make 20 ft.  As explain in John Haits book.

I plan on installing our wood cook stove inside the house hot water and cooking on which know is in our shop and heating it for the last 7 years.  

Im going for the mass not to be 100% no heat year round but to temper the stove spikes and to mediate the -40 winters here.    

Love the input back to the drawing board.

To address your concerns about water.  We or on a old ancient lake bed.  Lots of sand great perk rate.  The only problem I have is standing water in the yard, after the initial thaw and the ground is still frozen in the spring.  Once the frost leaves the ground the water goes to and it’s a dust bowl again for the summer.  I’m digging and will continue a dug out dig this is designed to take excess spring run off and store it.  This is were I’m pulling my back fill from.  This dug out can be drained each fall and pumped on the field to help the grass winter better, then be ready for the spring thaw capture.

I also plan on bringing the floor level up in the wofati to the same as my shop slab as we never have a issue with water there.  I’m pretty sure of course don’t know for sure but with a detailed umbrella extending out 20 ft I feel confident the posts under ground will remain dry also.  If a carry my gravel layer out and water sneaking in under the umbrella will hit the gravel and perk down.  Frost in the wet soil on the wofati will cause and surface moisture to run away.  My biggest problem is getting rain to water the roof during the summer keeping the roof green.

Currently my shop has a 6” slab 46x26 uninsulated 8x8 log walls r40 blow in ceiling.  Heated with our cook stove only through the winter, my daughter is bare foot most of the winter.  I’m a true believer in thermal mass.  It’s working great in my shop.  We had -12c last night I cooked supper fire went out and  21c in the shop at 8pm by 8 am the shop was 17c.  A small fire and cook breaky brought the shop back up to 20.  

Thanks so much for the feed back and challenging? I’m already adapting the design accordingly!
Byron

Dug out to be finished excavated and piled on the wofati.  This years run has already perked down.  It’s going to be shaped to provide cooling and reflection for the solar panels and greenhouse attached to the shop.  Need to pigs in when done to line it and finish shaping for me after I get the dirt I need.  

Sawmill ready to start milling down the timbers and lumber for the build

As you can see still cold here and muddy.

Some ideas to think about. Compact envelope to minimize heat loss perimeter. With your short summers and long cold winters, I doubt you will store enough heat in the exterior mass to warm the interior, merely enough to temper heat loss. I would advise concentrating mass around the heat source, like an RMH or other form of masonry heater, so that the mass can be made really warm.

All low buried wall edges, and a minimum of tall exposed walls. Plenty of high windows for penetrating light, but you couldn't make full window walls 12' high or the heat would flow out. Put transom windows in the bedroom south walls to borrow light from the main space, in addition to the exterior windows. Every point in the bedrooms would have direct view out the windows.

Very simple roof detailing to minimize chances of leaks. I'm not sure what roof slope is best for an earth-sheltered roof like this, but it may be that 3:12 as shown is too steep to reliably keep the earth from slipping. The peak might want to be lower for a flatter, more stable roof covering while still draining positively. For conventional engineered earth-covered roofs, 1:12 is recommended as the maximum without special anchoring for the earth.

Glenn Herbert wrote:The best central joint detail would have the beams resting on a ledge on the post, and lapping over the top to join them, similar to the edge joint; but this is distinctly more work than simply flattening the tops of the posts. I would do it myself if I were building such a structure. Flatten the post tops at the right level, then notch each side say 2" x 2", and notch the beams to fit. The beam cutting is no more complex than before.

Glenn, is the joint detail you're talking about the same as the left one on the berm shed?

Yep, that would be it.

Hi Glenn,  thank you so much for the drawing!   If it’s cool with you could I steal the design.

I’ll need to sit down and work out how to best run the beams and girders.

Much agreement  with you about the thermal mass not totally heating he structure.  ? Is how much extra heat needed to make the interior comfortable?  I guess we will have to build it, live there for 3 years and see how thermal inertia stables out.  

Wood cook stove going to cook meals and heat water in the winter should help a lot keeping the mass charged.  I’m lucky to work from home so I’m around regardless the fire will be going during the day.

Do you think its beneficial to have a thermal mass heater central in the wofati.  Heating the mass and allowing it to radiate into wall mass.  I’m leaning towards just using the cookstove as the walls will capture any heat radiating off the stove directly to the mass.

Possibly a well thought out rocket stove using the pipe through the thermal mass wall or under the floor to charge the mass?  

I’m willing to throw it out there and build the structure and see how it goes, worst case I have a barn, a shop, or a garage that’s earth bermed and still a usable shelter.   I’m willing to experiment with anything here!

Thanks again for your help,
Byron

I would be honored if you used the plan I posted; that's why I put it out there. Obviously all the internal arrangement is left up to you, as I don't know your personal needs and desires.

You could tweak the roofline to get a tall window wall all the way across, but this would significantly increase your winter heat loss both in exterior wall and subsurface near the south wall, and my feeling is that you would have a spacious main room without that, considering the central 12-14' ridge. You could put cozier use areas near the edges, and the main gathering area near the center, for a natural hierarchy.

My feeling on the beam/girder orientation would be to run the main beams horizontally (across the roof slopes), and the "rafters", poles or whatever, with the slope, so so that drainage if there is any will more naturally follow the slope rather than pooling in a divot between rafter logs. Of course if the envelope works correctly, water will never get near the actual structure.

I would want some experienced advice about the best roof slope; you want enough to drain reliably off the top membrane without pooling in irregularities, but not so much that the soil starts to slide downhill when waterlogged.

Ok still haven’t broke ground yet.  But I’m working on a agricultural grant to build my dig out / organic swimming pool.  I just found out I could get the a big portion of the dirt work paid for possibly by the ag branch.  Need to dump the dirt somewhere mmmm!

Sometimes blessings or in disguise.  As one of my meat bugs accidentally get knocked up and had piglets. Lol we called the vet and he says that there is funding for vet visits well I almost fell over!  

Further digging reveals funding for fences, irrigation, well drilling, dug out building.

Need to have a coffee with this ag guy.

Till I figure this out then I’ll start my build.

Been thinking about building wofati all over the yard know
Wofati wish list
Pig and chicken barn
Freezer and meat cooler
House of course

Maybe time to purchase my own excavator as they I could bill it out for the dug out build!

Awesome news!  After spending two weeks at Wheaton Labs and looking at the wofatis, it would be wonderful to see more of them built.  It seems the wofatis there were built in quick succession so the issues with the first one hadn't revealed themselves before the second one was built.  So now they have to fix both of them which is eating up time that could be spent refining the design further.  

Some issues to think about:

Some posts settled under the weight of the roof.  Pounding/pressing the posts in may be better than drilling holes.

Round wood joints on wall exteriors weren't filled with cob so it became mouse tunnels (between logs and innermost layer of plastic)

Too steep a roofline meant it was hard to keep soil on the roof or too much soil was added to remedy leading to too much weight

Getting an excavator sounds like an excellent idea!  When you're all done, you can probably sell it for 75+% of what you paid.  Maybe more if it's a charcoal fueled excavator

Heya Byron, I was on the team that was rebuilding Paul's earth berm shed last year and some videos were posted of that work, linked below. Pounding the logs into the hole with the excavator got them to sink several inches with the sandy soil. My own plan is to use a steel bar once I get a hole to 42" depth, and compact the soil down, then add landscape fabric to the bottom, which will keep the 6" of gravel I add for drainage in place. Then another piece of fabric on top, which will hold the borax, DE, and wood ash mix that is added to limit fungal growth due to any remaining moisture in the log which drains once installed. Then the log goes in, wrapped with something to keep the soil off, but the end of the log is not wrapped- just the 36" of the sides which will touch soil. That way the log drains into the 6" of gravel and once dried out should remain that way. Especially during the build, my concern is rain getting the site wet and having that wet soil against any wood for the days it takes to dry out. So wrapping the sides should help while the roof and then umbrella are installed.

If you can drain the umbrella to an elevation that's lower than the post hole depth, you should be set for rain, and as long as the water table stays several feet below during spring runoff/rain season it should be all good. I bought some 1" wood dowels to cut out "logs" to build a scale model, and you can then cut out furniture with paper to move them around to get a feel. My own property is pretty flat, I will build where I have a bit of drop as I plan to dig 4 feet down, so I want to french drain the umbrella perimeter to sunlight below that. Was also planning to add an earthship-inspired greenhouse on the south wall to use as a buffer in winter and try growing warmer plants using some techniques from the book The Forest Garden Greenhouse. Might work for you as well, add a few months to the growing season and you could run sink/shower gray water out through it to the outside. Perhaps compost the toilet Humanure style.

Shorter Video:


Longer Video:

Thanks Mark,
This is all good insight!!!

Still working on a couple funding options lol!   Gov can be slow!

It would be interesting to do some research on timber framing because there are different methods to achieve different goals.

I know here in New England, the Timber Frames of old barns were designed for heavy loading on the inside of the structure. That is, all that hay in the hay mown had to have timber frames that withstood internal forces. This is actually quite different then the forces acted upon as a house does. Its been said that a lot of old timber framed barns in New England have died because they no longer were being used. Without weight within, they were not putting the frame under compression keeping it from being pulled apart.

A method of timber framing that does hold up external forces incredibly well, was a timber set system known as "The Square Set". It was used in mining to help hold up the back of the mine (Back=top of the mineshaft). This was used in the famed Comstock Lode to extract all the silver out safely. It was time consuming, and thus expensive, so it went out of favor in 1910 or so as another method of timbering a mine was done. However it worked, and today is still holding up mine shafts from 120 years ago. Without weight, snow loads pushed out and ripped the frames apart.

I am not saying you are doing anything wrong, just giving you some researching options that might work for you. Mine shaft? WOFATI...the same dynamic forces are at play.

If we depend on plastic sheeting and styrofoam then why not extend the convenience to the use of cement filled concrete blocks for walls and posts?

I think the standard wofati construction method doesn't use styrofoam.  There is a fair bit of poly sheeting but there is the hope that it can be reclaimed from the waste stream in the form of billboard tarps or silage tarps.  Cement has a fairly large carbon footprint.  As built in Montana, with low ground water levels, I think the idea is that posts in the ground will survive.  Thus the design is how it is.

If I were to build one here where my ground water is much closer to the surface, I think I'd adjust the design a bit.  But then I couldn't call it a wofati...

Burl Smith wrote:If we depend on plastic sheeting and styrofoam then why not extend the convenience to the use of cement filled concrete blocks for walls and posts?

I kind of wondered about this myself, but then I got a book form the University of Minnesota on building underground, and their study was intriguing. It showed that just one inch of Styrofoam could have the same benefit as 3 feet of earth. That really got me to thinking, if my WOFATI had to be built so much more robust to handle the extra weight of all that earth, why not just use Styrofoam and scale back on the building to hold it up? Or better still, use 2 inch of Styrofoam and 18 inches of earth and get a really efficient building? That would be the equivalent of 6 feet of earth over the roof.

I understand the green building of something, BUT if it takes 20 times more of a Green Building material to get the same efficiency, I cannot see how that is an improvement to the earth. In this case, it would take so much more wood to build it 100% green round wood...that just logging that much more wood would be counterproductive green wise. And moving 6 feet of earth would be energy-costly as well.

What I am trying to say is: how many square feet of Styrofoam will a gallon of oil produce? I know how many cubic yards of earth a gallon of diesel fuel in my excavator takes, and it is not a lot. At some point moving earth is going to exceed how many gallons of oil it takes to produce the Styrofoam. I am not advocating anything in particular here, I am just saying that research has to be done, then the math carried out.

Do you know if that Minnesota study was with dry earth or normal/moist earth?

Definitely sounds like dry earth which gets about 1R per foot, while wet earth takes 10-20 times more per R.

There’s a web site which sells recycled billboard that I’ve looked at, 40-60mil material without breaking the bank. As I don’t have enough wood duff to use for insulation, the poly sheets which are 2” thick should work fine. Suggesting that going green is an all or nothing argument feels like a Strawman; concrete is probably the worst offender of energy use in my book, so just eliminating that is a really big step forward.

I wouldn’t call my build a wofati for several reasons but certainly an Oehler/Hait hybrid. Hait’s Umbrella is a proven design with decades of use. Oehler’s design is similar, with just protection of posts being a work in progress from what I’ve read.

Mike Jay wrote: Cement has a fairly large carbon footprint... Thus the design is how it is.

I see you with Green Concrete Blocks

A lot of companies are trying to develop new technologies and replace conventional cement to reduce its carbon footprint, but CarbonCure takes a really simple, logical approach to getting rid of CO2: It puts it back into the concrete. Then the magic of chemistry happens again, as it bonds with the cement and essentially turns it back into limestone.

...and raise you the carbon footprint of alcoholic beverages.

Those are nifty sounding.  Hopefully they become widely available soon.  

Perhaps in the final analysis the widespread availability of green concrete would offset the consumption of alcoholic beverages.

Burl Smith wrote:If we depend on plastic sheeting and styrofoam then why not extend the convenience to the use of cement filled concrete blocks for walls and posts?

Isn't there a middle ground? What about a concrete footing that the wood post sets on above grade? They build decks that way.

Or forget concrete: a stone footing with a minimum of cement mortar?

Yes I think so Nathanael, I just educated myself on the carbon footprint of alcohol and found, to my surprise, that it's in the packaging, transportation and retail. To be sure I think a middle ground is a worthwhile pursuit.

I'm not sure why you're bringing up alcohol Burl?

Nathanael, I'm sure there is middle ground regarding cement in a wofati.  I think some of the reason for the posts down below the floor of the wofati is so they can resist the significant side loads from the dirt against the sides of the buildings.  I'm sure there's a way to manage that with a footing but I'm guessing that's the reason for posts in the ground.

Mike Jay wrote:I'm not sure why you're bringing up alcohol Burl?

I'm sorry; perhaps the consumption of alcohol isn't a factor in the construction of wofati.

Not to be an antagonist by any means, but I do not have a big problem with concrete, and use it quite often. But here is the thing, I have my own gravel pit, and a cement mixer, and so I make most of my concrete myself. I do not have a limestone quarry though, so I do have to buy bags of Portland cement in which to do that, but proportionally it is not too bad. It takes 470 pounds of cement bought, for every 3000 pounds of concrete made.

To me, this is really no different then using wood. I have a vast forest here, certified under the American Tree Farm System, and so I log, saw on my own sawmill, and joint and plane my own lumber, yet at some point I still have to buy nails or screws to put it all together, I admit that converting limestone into Portland cement is intensive, but so is smelting steel to make nails.

To me, the biggest point of this is, doing as much for yourself as you can. That not only saves resources, but allows a person to learn new skills, and puts them in control of quality.

I think concrete holds a lot of promise for a homesteader. Even if a homesteader does not have a gravel pit like I do, they can still use other medium. I have successfully used Earthcrete, which is quick and easy to make, as well as making a lightweight concrete floor with sawdustcrete, which used sawdust instead of aggregate as a medium. And just yesterday I had a friend who does not have his own gravel pit, but needing to pour some footers, borrowed my cement mixer and bought gravel to make it. It was a minuscule $158 for 14 cubic yards.

Myself, I have poured my own concrete slabs for buildings, built chimneys, made (3) concrete countertops, grouted a entryway using native slate that I hand-plit myselfm shimmed sloping floors; goodness I have done a lot with concrete, and I think others could as well. Considering how versitile concerete is, I think it is a shame not to use it around the homestead, BUT I say this assuming people make their own concrete, earthcrete, or sawdustcrete.

Icidentally; despite making a lot of concrete and sawdustcrete; I use my cement mixer more for mixing starter soil, potting soil, garden soil, washing rock, mixing paints, and other tasks then I do making concrete. My cement mixer is a HUGE tool on my farm.