wofati 0.8 - cooper cabin

Feb 26, 2014 07:46:54

Update!

This project started off calling this structure "wofati 0.8" and was later renamed to "Cooper Cabin."

It is currently about half done, but people have been living in it from august 2014 to present. Currently it is available for weekend or weekly rent here.

This structure features the rocket mass heater that is the primary build example in the book The Rocket Mass Heater Builder's Guide

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Tim and I have been talking about the next wofati. He's asked me to draw some stuff up so we can work out the design. I think he said to go for 800 square feet for 0.8. So, of course, I went and made it twice that size.

Well, should be good enough for the first round of feedback anyway.

Here are the first images:

Feb 26, 2014 07:48:00

... and a cross section & the working sketchup file

Feb 26, 2014 08:05:00

What don't they like about the current one (other than the size)?

Do the posts bother them? Would changing the timber size and making the span a little bigger make it easier inside? Or are they not a problem and you should reduce the span so you can use smaller timber?

Feb 26, 2014 08:15:41

would be neat to include dimensions or at least say the spacings--if that's 1600sq ft, 40 feet on a side posts are 8-12 ft apart?

Feb 26, 2014 09:18:41

R Scott wrote:What don't they like about the current one (other than the size)?

Do the posts bother them? Would changing the timber size and making the span a little bigger make it easier inside? Or are they not a problem and you should reduce the span so you can use smaller timber?

It's mostly the size. 400 sf just a little cramped in the middle of winter with 3 kids and all.

Tim's ok with the posts. Other than the size, the greatest concern is to streamline the building process. We've switched up a few details with the beams and how things will go together after that. More details to come as we work through things.

Feb 26, 2014 09:20:33

bob day wrote:would be neat to include dimensions or at least say the spacings--if that's 1600sq ft, 40 feet on a side posts are 8-12 ft apart?

As we zero in on the actual design, I'll include more details like dimensions.

The stuff above is all on 10' centers.

Feb 26, 2014 10:08:50

Jesse Biggs wrote:
It's mostly the size. 400 sf just a little cramped in the middle of winter with 3 kids and all.

Ya Think?!?! LOL

Feb 26, 2014 13:08:11

R Scott wrote:

Jesse Biggs wrote:
It's mostly the size. 400 sf just a little cramped in the middle of winter with 3 kids and all.

Ya Think?!?! LOL

Lol... no i know its too small!

Feb 26, 2014 15:03:11

I really like the look of that layout. Along the lines of what I want to do and where I already have a hole dug. Now I'm just trying to figure out where to get the dry dirt, since my hole was all rip-rap and was used to level out the road into where it was at, and make a nice shop sized landing.

I'm going to have to look into this sketchup doohickey.

Mar 07, 2014 13:02:58

So what are your assumptions about timber sizes and dead/live loads?

I know that it is earth fill for the roof and then snow on top of that, but for a 20 by 60 space you might be able to reduce the columns and beams?

I think you are using timber found on site for the main structure and it appears you are using 12 inch rounds at 10 foot centers.

The info in the attached document indicates that a 12 inch hemlock can span 20 feet with a uniform load of 290 pounds per foot at l/240 deflection.

From this link:
http://www.reade.com/Particle_Briefings/spec_gra2.html
I am getting some cubic foot weights

I am thinking 2 feet of dirt and 3 feet of snow and 1/2 foot of timber roof deck is (95+ 95 + 45 + 45 +45 + 13 = 348) of course there is the tributive area thingy...

So the 10 foot centers seem conservative.

If you did the main roof deck in 12 inch timber, you could go with a 20 foot span and maybe 15 centers on columns to free up the interior space?

jus' thinkin'

Mar 07, 2014 13:51:09

I love the Wofati.

I'll bet this post gets some debate.

Carrying dialog from the first one to this discussion which seems to be more timely, I share from Post Frame Building lessons the following way to set a post in Missoula area to alleviate many of the concerns over contact with the earth that have been shared.

Minimum footing frost depth in Missoula is 42 inches: this is to avoid frost heave, which is very real. The hole needs to be bigger than the pole by three inches or more all the way around. The bottom of the hole should be soaked over night with some water, but not a lot. the next day when the water is gone and the dirt isn't sloppy, the bottom of the hole should be compacted with a tamper/pole to where it does not compact the dirt any more (bounces).

NFBA and USDA both indicate a big rock or concrete pad (4 x 8 x 8 solid cmu) be placed in the bottom of the excavation/hole. In the drawing this is below 42 inches just to be safe. Once the pole (no bark) has been set into the hole, crushed gravel (clean, no fines) is placed around the pole. The gravel is placed in lifts of about 4 to 6 inches and a 2x4 tamp is used to compact it into place while the pole is kept in alignment. Place gravel to the top.

DO NOT PUT CONCRETE AROUNd THE POLE...it will trap the water and cause rot.

I don't know how 'green' it is but painting the hidden part of the pole liberally with creosote is popular and has worked for railroad ties for a century or more.

Mar 07, 2014 14:07:36

Ty, I'm thinking the above method with black locust, sans creosote, might last a REALLY long time.

As for the load calculations, more like 3' of both soil and snow would be a safer figure.

In Mike Oehler's book he has some nice little drawings of how to work poles into built-in furniture and features. I think I might have been a bit sleep deprived when making the above model and have updated it since.

After a couple more back and forths with Tim this is our current design:

Mar 07, 2014 14:15:07

...So what are your assumptions about timber sizes...

Tim's got me drawing the structural members w/ 12" diameters. The roof decks @10", and the walls w/ 6" logs.

A couple more images:

Mar 07, 2014 14:19:19

Yeah, baby!

That is definitely working.

Those loads are huge! That's probably why Hogans were octagonal and pretty small. Cotton wood is a lousy load bearing timber.

Have you looked at x bracing the perimeter posts to help with the roof load to ground transfer, or is it even a problem?

Apr 21, 2014 23:50:03

Shipped these off to Tim a few days back... this is where we landed in our 0.8 design discussions:

Apr 21, 2014 23:51:20

...and 3 more...

Apr 22, 2014 16:06:26

So, I get the earth sheltered part, but it seems that the loss of the solar-gain wall on the hillside slope is contrary to the Wofati principals. What is behind the notion of three sides buried?

Apr 22, 2014 16:32:23

Ty Morrison wrote:So, I get the earth sheltered part, but it seems that the loss of the solar-gain wall on the hillside slope is contrary to the Wofati principals. What is behind the notion of three sides buried?

I've seen this question come up quite a bit. It's a common misconception that wofati design has anything to do with solar gain or passive solar design. Paul has gone on record stating that he wants to prove the design will work with no regard whatsoever to solar aspect or orientation whatsoever.

It's all about thermal inertia. Not pictured in any of the drawings here is the "umbrella". This detail is possibly the most important part to pulling off the no heating or cooling thing. Here's the idea in more detail: some of John Hait's stuff

Apr 22, 2014 16:48:52

Ahh. Thanks for the clarification.

I thought the solar well was more for quality of life and light. No heating or cooling is very important too. I also am reminded that budget was a goal as well, $300?

Ok, so why the step at the back?

Kivas and Hogans were definitely Wofati predecessors.

Jul 01, 2014 07:34:45

Kristie posted this pic a coupla days ago:

Last night somebody asked about hours to build and Tim replied:

I would have to say from the first log fell to when the umbrella is on that over 3,500 hours were/will be spent building 0.7. Many lessons were learned and I hope that 0.8 will take under 1,500 hours. And 0.8 is going to be 2x as big. I can imagine we can get it to about 1,000 in time. Log falling,skidding and pealing are a good 50% of this time.

At the same time, Tim said that if we have a pile of logs prepped, he thinks himself and one other (good) builder could build a 10x10 wofati in a weekend.

Jul 02, 2014 21:06:09

Some photos from our work on Wofati 0.8 today:

Jul 05, 2014 11:40:58

Lincoln logs for adults

Jul 05, 2014 11:43:17

Jul 05, 2014 11:43:38

Jul 05, 2014 11:48:58

Starting the first pin

Jul 05, 2014 12:22:23

Beam is in place. Getting pinned down.

Jul 07, 2014 16:01:39

Jul 08, 2014 20:14:15

Thanks for sharing the pics, this is really exciting.

Jul 09, 2014 16:59:29

The problem with long logs a narrow log arch and a sharp right hand turn

Jul 09, 2014 17:14:53

Ouch, that's gonna leave a mark...

At least it didn't flip the UTV.

Jul 09, 2014 17:27:33

Hey Tim, those end connections are looking mighty fancy. I'm curious to know the "why" behind them. Looks like you are indeed going with no elevation changes. Looking like pros at this!

I think when you google "permie" there should be a picture of Tony in his hat and suspenders. He's nailing the look so hard right now!

Jul 09, 2014 18:44:51

We did the ends in a kinda shoulder nothch to help with dirt pressure pushing the poles out from under the beams.

Aug 03, 2014 16:18:38

Looking good!
It seems like the logs are taller than the ones in the drawing. (e.g. back logs at 12 feet, middle logs at 8')

Is the idea to raise the finish floor a bit, or did the project outgrow the plans?

-Erica

Aug 03, 2014 16:20:12

Jesse Biggs wrote:...and 3 more...

I'm also curious about the broader wings in the back. will there be windows to a sort of light-well / back garden where the terraces are back there, or just a cavity space?
Is this back part designed to shed water off the main structure?

-Erica

Aug 04, 2014 11:09:35

Erica, here's my understanding of the "back area":

There are 2 things going on there...

1) It is shown here as kind of an "uphill patio" as found in Mike Oehler's book. The idea being if you're building on the side of a hill, and the hill wants to "go visit the neighbors", you have this whole area as a buffer zone to that kind of activity.

2) Paul has added more of an overhang and the fancy "wing walls" to further protect the exterior bits of the wofati from the elements.

That's my version anyway.

May 20, 2015 17:15:06

A few pics of the inside of wofati 0.8.

Jul 08, 2015 18:06:53

I just finished a bounty project on 0.8, facing the front wall to cover up the tarps and improve the outside appearance. I used some 3/8" by 4" lumber that was milled on Paul's mill. The front wall will eventually be covered in cob, so this facing will also give the cob something to stick to.

Jul 08, 2015 18:43:26

Looking good Jesse! Too bad ya started on that the day I left =)
Scrolling up, it looks like new interior pics may be in order, since we pulled the walls out to open up the primary space in there.

Jul 08, 2015 21:05:41

I want a shot from a drone!

How's about a whole fly around?

I want to see the rear side of the structure and berm - it looks different than the SU model.

I want to see more.

It looks like the space has been subdivided...that sort of plan view (Jesse's SU model depicts the concept, but it would be nice to see how the users are thinking of the space when they turnkey.

KEWEL!

I found a beautiful pie. And a tiny ad:

Get Paid to Build a Permaculture Paradise at Wheaton Labs!

https://permies.com/wiki/178360/permaculture-projects/Paid-Build-Permaculture-Paradise-Wheaton