Coop with plywood siding straw insulation...

I'm in the process of modifying my coop to be warmer in the winter, cooler in the summer, and more predator proof.  It's currently 2x4 construction with beadboard siding that's about 5/16-inch thick.  Reading an article in Mother Earth News about plastering a straw bale house made me wonder the feasibility of using straw as my insulator with slats or lattice to hold it in place then coating it wth plaster and whitewashing it all.  There's also a concrete floor to consider.  

Should this work as far as breathability year-round?  We're in the mountains and average 60 inches of rain a year from October to May.

What type of plaster material should I use?  I've got soil wth a decently high level of clay if that would work.

I saw another article where pallets were used to construct a variation of a cob house and I think I'll use that for my new goat shed.  I'm rebuilding totally after predators broke into the old one twice.  Can't do a full cob or straw bale for the chickens though since we aren't doing a full tear-down.

Hi Mary,

Sounds like you're talking about doing light clay straw(also known as straw light clay or slip straw). It's breathable and has R value of approximately 1.5/in. Sounds like your soil will work for the light clay straw binder and probably for the plaster. I might add borax into your light clay straw mix to prevent insects from trying to nest in the walls. Here's a video  intro about light clay straw:

Personally, I'm not sure it helps to have an insulated coop.  My experience with coops is that they need so much ventilation that the interior temp is pretty close to the outside temp.  The biggest issue I've had in the winter was too much humidity caused by not enough ventilation.  That resulted in some slight frostbite at -40.  Since then I've made sure to provide lots of ventilation and I've never had any frostbite at the same temps.  I don't provide any supplemental heat and the girls have always been fine.

Has anyone found a balance of insulation and ventilation that works?  I could see adding insulation or thermal mass to the south side in a warm location but that would prevent passive heating in a cold winter.

I'll look into the slip clay.  Thanks for the info.

As for the insulation there's still plenty of ventilaion and I'm not doing it as much for the temperature regulation as for the added wall thickness.  I'm just adding extra layers in case the bears decide to attempt entry again next summer.  More layers gives me more time to get out there.  Plus I'm hoping between the better roof and thicker walls hubby can tolerate a rooster 😂.  Once they start crowing before the alarm clock they go 😢.

We've got black bears and between July 2019 and August 2020 we've had 4 attacks on our goat sheds (three in one night between two sheds) and two dead goats - one last summer, one this summer.  There were also 3 attempts on the coop over the last year with no successful entries only because the coop is closer to the house and the dog hears that more easily and we can see most of it from the house.  

For the coop I've got a climbing rose trellised on fencing on the back wall and I'm planting an extra prickly juniper or three on the hillside that was used to climb onto the roof a few months ago.  I'm rebuilding the roof to repair the damage and make it stronger too.  Then rebuilding the run because it was a crappy build anyway and the bear partially collapsed a section is wall as he got on or off the roof.

I know nothing will truly stop a determined bear but every little bit helps!