[Cob] cobscrap logistics - kiln dried cutoffs and Cob - quasi Cordwood

[Marlin Nissen]

Rob,

I'm not sure of your foundation situation....whatever courses of urbanite you'd use on a Cob wall would be similar for any type of cordwood (cobscrap) I suppose. In the great white north it's the freeze/thaw that has to be taken into account.

I think an outter wall should be several inches (4? at least) with an insulation gap at whatever width based upon the 2x4s length that spans the 2 walls....the thermal mass comes from the cob INSIDE the insulation gap and that's the wall that will have the beef to be the load bearing wall. If you use enuff 'mortar' type stuff over the outside wood ends I think it won't fall off because of the wood to Cob adhesion. I wouldn't put just a little thin crust over the ends of the wood. 

I've never tried it but would think that for creativity you COULD arrange the 2x4's into patterns and leave them exposed like in Cordwood. Bet a 'wave' or sunburst could be created with a little forthought?

>From what I'm hearing NOW about wire inside Cob I wouldn't recommend ANY metal (to count on it anyway) INSIDE Cob walls as the humidity/clay will eat up/rust it away. Wood yes, metal NO from the people that have cut into Cob walls after years and years, so I guess I would NOT recommend any chicken wire. Cob adheres well to other Clay and pretty good to wood. I wonder about plastic netting too?

Let me and the Coblist know what you try and send pictures. I haven't gone dumpstering for scrap wood for a long time but a pickup and a good new subdivision used to give tons of wood cutoffs. Then a good Chop Saw will cut them ALL to the exact length for the width of your Cobscrap wall - which is a real bitch with Cordwood and a chainsaw setup - not to mention the shrinkage factor.

Best


Marlin


--- On Mon, 6/1/09, Rob Hayes <editable7 at yahoo.com> wrote:

From: Rob Hayes <editable7 at yahoo.com>
Subject: cobscrap logistics
To: "Marlin Nissen" <marlin_nissen at yahoo.com>
Cc: coblist at deatech.com
Date: Monday, June 1, 2009, 11:17 PM

Marlin,  
That's a great idea & I don't know where I was when you'd mentioned it before.

There are everywhere many more dumpsters full of TONS of this sort of material & I know not to pick too much of it up for firewood.  But the beauty of having the occasional nails protruding is that they will ADD to the attachment to the building mass!

I was just wondering what to use for the farms' missing shed endwall to keep the chooks feeling safe.  Now, I can more easily visualize a cobscrap hipwall with window sill and those recycled window sashes mounted above.  

2 questions:
a.) Since the roof load is carried by the adjacent walls - how many "courses" or layers of urbanite recycled concrete sidewalk pieces would be good for the first
 ground  contact layer?  I wonder if my trusty old 3/4 ton Dodge p/u truck could be called into service  for compacting them.  Or should some stone or lime consolidated crushed gravel be placed there and have a trench first?  There is some roof overhang there, luckily, and fortunate site drainage slope.
b.) if the cob exterior starts out with a say, 3/4 inch thick layer, should a chicken wire mesh be held out 1/2 inch for reinforcement?  Won't thin cob layers on the 2x4 "ends" tend to jump off after slight impact or after drying?  Or should some strawy cob mortar be caused to stick out from between the wood scraps courses enough for the cob plaster connection?

I'm ready for the logistics of setting up a barbecue on the other end of the shed.   Even if it rains and invited people get there late - something good is likely to happen. I like the "extra thermal mass on the inside" idea too - another rainy
 day project waiting there in a blue tarp scrap for those willing and able..  


Marlin Nissen <marlin_nissen at yahoo.com> wrote:

"...my take which I've mentioned before is to use 2X4 cutoffs as the 'cordwood' and have them all cut to the same size with a chop saw.


Benfits of 'CobScrap'


1. They're uniform in length
2. don't need ANY drying so they won't shrink
3. free in the construction dumpsters/waste going to the landfill
4. if you Cob OVER the ends of them the wall will look just like a Cob wall!
5. you end up with an insulation gap between the 2 walls - bonus
6. from my estimates you have to make about 50% LESS Cob - less mixing
7. the walls are lighter/dry quicker so you can go higher on the wall much quicker
8. if you
 build a bigger INNER wall you have a good thermal mass INSIDE your structure where you want it to regulate temperature swings
9. the wall looks EXACTLY like Cob!
10. there's 1000's of anchor points for cabinets and other attachments to the cob wall, JUST below the surface of your walls.

=========================  "The past has vanished, everything that was uttered belongs there;
                   Now is the time to speak of new things."                    ~ Rumi "...
.............................................................................................................................

and thanks, for making room for Rumi too.

If the door is shut

right in your face

keep waiting with patience

don't leave right away.

Seeing your patience

your love will soon

summon you with grace

raise you like a champion.                - Rumi