Jeremy Krieg

Wow that paper is very handy, thankyou very much ... It will be a good reference (Here in Australia there are a few other published cob reports .... 'the Earthbuilders Handbook' published by the CSIRO),

Fortunately for me, the structure I am building is below council regulation (so I can basically do what I like !) ... so I although I have been in contact with several engineers I do not have one for this project.

There are too many variables !! ahaha I also need to consider the weight of the cob eaves (further I go out the more stress on the cob ).

Hmmm ... things to consider !

Thanks Ben ! Yeah ahaha ... there was quite a time when I couldn't sleep thinking about whether they would work or not,

I have made all the cob by hand (starting with a backhoe but then forming each ball buy hand adding straw when necessary), I didn't embed any extra reinforcement ... I spoke to an engineer once about adding timber and he said the straw is reinforcement enough (I don't think he understood the material properly). I did however do a tension test on my cob mix a few years ago and it was quite promising (I embedded two welded prongs in some cob and then hung the cob block vertically and added weights to try to separate ... I ran out of weight ! ahah pics below) , so I believe so long as the cob is mixed well and then laid intelligently (so you have long thicker strips that 'tie' it back into the structure we should be alright ahah),

Yeah the arches will be built up to about 300mm at the crown, I can hang my weight of each crown though at the moment (70kg so I am pretty happy with that already),

I think the buttresses would be a good idea ! I would not be at all comfortable with someone else building these eave supports (and I don't think I would do it readily again in the future), I was very careful with how built them and the cob I used (and I have tested their strength the whole way along).

I think the timber is a good idea (I was going to have to embed some into the top of the arches and eaves so I have something to nail the timber I will span the arches with).
Good point about failure (I plan to do many safety tests once the roof is on, adding extra weight), but It would be good to have a bit of a warning if anything was to happen.

I would like to go on after this project and scientifically collect some data on how cob performs under different loading

Any idea Ben on how far out eaves on a cob house should go ? (I was also thinking if I do put the timber on top of the arch if it was strong enough I could extend it out slightly further past the end of the cob eaves to get me a bit of extra distance)


Thankyou very much !

Here are some more pictures showing these "eave supports" ahaha

The second picture is looking down on the wall, the cob that runs horizontally in the photo is the main wall and the vertical cob makes up the internal arches (which support the roof) (in the photo that is above the main wall) and the vertical cob bellow the horizontal main wall forms the eave supports, because the internal arches and eave supports align I can ties them into one another reducing the stress on the main wall (i.e so the weight of the eaves is not just bending of the main wall but it is also supported by the arch which reaches across to the other wall)

that's a bit confusing, I will upload a video soon

Hi Permies !!!

I have been interested in cob for a while now and I have almost completed my first house/studio. I started researching cob as part of a year 12 assignment and I started this structure late 2014 and have worked on it spasmodically.
I have tried a few things that I haven't seen on the internet before (a vaulted cob load bearing ceiling, cob arches/trusses to support the roof and cob eaves !), I resumed building the week before last and hope to get the cobbing finished by next week ! ahaha (as I have to go back to uni the following week).

I was wondering if anyone has any advice on the eaves, (at the larger cob supports come out over a meter from the wall and smaller cob supports are about 600mm), I intend to span these supports with salvaged pallet timber and then have a green rood on top (I already have some cardboard and a waterproof membrane) ?

Thankyou very much

Jeremy

The regulations state

has no span exceeding 3 meters, and no part of the building being
higher than 2.5 meters above the natural surface of the ground;

http://www.legislation.sa.gov.au/LZ/C/R/DEVELOPMENT%20REGULATIONS%202008/CURRENT/2008.233.UN.PDF

they don’t specifically mention eaves but wouldn’t it be included as a total span from one eave to the other eave .
I've had enough with stupid council the hand sculpted house said to avoid at all costs I should have never mentioned it to them


Allen what do you mean about the insulation , the outbuilding is on my parents land


thanks so much everyone

Jeremy

thanks Connor , there is so way i would waste the water id like to have a green roof and i collect the run-off with some sort of gutters . I understand the water trapping concept - I Ignorantly put a concreate stucco on an earthan pizza over the year before last - but wouldnt linseed oil be a bit different considering people use it all the time for earthan floors and benches?

Scott , our climate isnt realy that dry - although we have droughts often -


thanks guys

Also I made a model of my house in Google SketchUp for council , Ive just uploaded it

Hi guys,

I'm building a cob house in South Australia at the moment, well I am trying to. I am only 17 and all of the hoops that council are making me jump through has become too much (get this my home made ladder would not fit with the Building Code of Australia as it is 'inappropriate access to a habitable space’). So my plan of action is to fit within 'structures that do not require planning or building consent' as per the state regulation ( I originally was going to try and work within this , as I know many in the US do , but some early miss information sent me off to council ) .
To fit within this part of the legislation the building can only be 2.5m high and 3m wide ( I am going to assume this is internal measurements considering my cob walls will be 0.6m thick ) , I was originally planning on having a reciprocal roof but now I have no room for overhang so I am looking at a flat earthen roof ( on a slight angle for run off) similar to the vaulted arch video on YouTube @ 25.03



, I like the walkway around the edge with this I could grow a few things on the roof. Although I really like the reciprocal roof I am real keen for this new design .....

But the problem is that there would be no eaves as If I built them I would be outside the section in the legislation - hat and boots theory out the window -, so I was whether several coats of linseed oil would protect the cob from the driven rain - uncovered cob benches are just protected this way aren’t they


Any advice would be great


Thanks so much

Jeremy
(Also I am doing this as a school project - believe it or not - and its due in a few weeks , but dad owns a backhoe that I can use efficiently to make the cob )

Thanks heaps again Luna,

the hammock will be part of a loft and the rafter idea is great ,
otherwise the deadmen sound good ,

im working out permits and stuff now , but latter on ill upload some pictures
thanks heaps for the advice

jeremy

thanks heaps Luna ,

yeah deadmen sound good , but are you sure it would be strong enough - id be sleeping in the hammock -

what do you think about having a few boards of wood with deadmen on them then attaching the hammock hook to the middle of the board
the board would be compleatly embeded in the cob wall

thanks
jeremy