Dale's cob over drywall cabin

When drywall is applied to new construction, there are many off cuts which are thrown out. I am going to try to get paid to haul away enough material to completely cover the inside of my 600 square-foot cabin. This will be a substrate on which I will place a thin cob finish.

 The place is framed with 2x4s and has a plastic vapor barrier over fiberglass insulation. The drywall is meant as a backing. I think I would damage the vapor barrier many times,  if I tried to apply the cob directly over the plastic.

 I will use hundreds of little screws or nails to hang the cob from the drywall. Light wire may also be used.

 When the mud goes on a regular drywall project,  there is plety that gets wasted due to dirt or hardening in the bucket. Lumps won't matter to me. I will mix free drywall compound with clay In order to get good adhesion between the two products.

 The finished product will be completely covered in cob, so that no drywall is visible.

The gypsum and paper in drywall scrap could be added to the clay as well, I believe both can be used in earthen construction.
The screws ... To many means too much work. Plus, the ones that only hit drywall will not be well affixed. Screws in studs with light wire I between seems like a good compromise.
Ever tried coming used carpet, either side?
Hell, run those screw as though some branches for a sort of wattle?


Dale you are an inspiration, as usual.

I'm currently experimenting with American Clay I believe to be a mix of Kaolin and calcium bentionite with small amounts of an acrylic binder, fine 80 grit jagged edge sand in a scratch coat of no voc primer, also a lime/pumice mix from Limestrong on a gypsum mud sand scratch. AC held up well in an adhesion test, Limestrong came off easy but Bill Bradbury said that is because I did not babysit and wet the lime for at least week once a day (too much work imo)...so he said to try a economy grade gypsum base and lime wash paint I can pigment any color I want thats next. I just got home with some more drywall to add to the mock up. I tried all products direct to drywall to see if I could cut cost, worked but AC said " not indicative of a whole house"...in my mind the clay IS the primer... I'm using mineral wool roxul that calls for an interior barrier(plastic) I do not agree with. The problem with metal is the corrosion resistant coating lath will ware off, wood is expensive unless you buy sawn by the tons.

Good idea to mix some mud in the COB for better adhesion, helps with dissimilar material issues.

To cut cost I thought the stiff unlike FG mineral wool would support using chicken wire but that did not work. I'm a noob plasterer.

Here is the thread the'll be some updates this weekend: So far I have concluded drywall makes a cheap fast backer board for the right renders....however if people can afford it I recommend wood lath. https://permies.com/t/49723/natural-building/Natural-Home-Mainstream-Home-Cost

Thank you, William and Terry.

I don't expect to purchase much of anything for this project, other than a small amount of wire and nails. I already have several tubs of odds and ends of screws and nails.
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 I hope to get new scrap drywall. If I don't get that, then I will only use drywall from a demolition that was installed after 1990. There was no asbestos allowed in Canadian drywall after that date. I expect to make at least $300 on the drywall disposal and to spend less than $50 on other supplies. I'll be charging some labour as well, to gather the stuff up. So,  either I'll be picking up used drywall from a job which I have contracted, or I will haul scraps for professional drywallers. Either way, someone must pay .☺
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 Digging at clay and liquefying it is hard work. Luckily, there are always people in the city who are doing foundation work by hand. Many of them place ads on used Victoria asking for people to come and get the stuff. They produce clay that has already been worked up into a froth. I gather it in five gallon buckets. This is a nice size for lifting and it's a good size to put a drywall mud mixer in.   I'll whip it up nicely before taking it to the cabin.

Yesterday, I paid $30 or about $20 American for this heavy drill and drywall mud mixer. The drill is very low speed, high torque machine.

 Last week I mixed drywall mud with a much newer Makita drill. It was geared too high for that purpose.