Chicken coop design process Pt. 1

As we sit through winter and prepare for the arrival of spring, and the changes that will bring. The Lady of the House has her focus settled on the garden, and I am trying to have a design for the chicken coop nailed down as much as possible before mud season begins. Below is my first draft considerations for the requirements for the coop, with information that is informing this and my next steps of the design process.

Primary requirements for our chicken coop.

Sufficient size to comfortably house 12 chickens.
Each chicken needs 3 - 4 square feet of inside room and plentiful run room. If we don't have a covered run we need to err on the side of 4ish sq ft per chicken inside. That means we need to be looking at a  48 sq foot space inside the coop. That gives us an approximately 4' by 6' minimum foot print for the number of chickens the Lady of the House would like to have. As a note, there are many different ideas of space per chicken. The one that I am looking at as a good baseline is about 10 square feet per chicken between inside and regularly accessible outside space. This seems like a good balance between "Good lord, how much will this cost?!" and having an ethically acceptable space for our chickens to stay with our primary goal of ethically raised and cared for animals.

Sturdy enough to handle winter.
We get a lot of snow, a lot of wind, and it stays for quite a while. We aren't talking Alaska here, but it is a consideration. What that means in my mind is a roof that can handle 5 feet of accumulation of ice and snow as well as small branches falling on it. It will need insulated walls and roof, as well as tightly fitted doors and walls to minimize wind chill. A good phrase is ventilation, not drafts. It also means that we want to have south facing windows to provide some heat help in the winter. Ideally for heat reasons the floor would be a little below ground level and be dirt or stone to minimize thermal swing.

Predator proof, or as close as we can get.

A list of predators we have confirmed by sight within 50 yards of the house, most of them on the porch.
* Black bear
* Fisher cat
* Red fox
* Snakes including king snakes and rat snakes.

Predators we have strong evidence from tracks and scat within 50 yards of the house.
* Coyotes
* Gray fox
* Some form of weasel which could be a mink down through a least weasel.

Predators worth considering without evidence.
* Raccoon

So what do we need to deal with these predators, as well as discourage pests like rats and mice. Obviously a sturdily built structure is an important first step to keep it from being easy to damage and destroy. For most of the predators no gaps anywhere would be ideal, but there does have to be ventilation to prevent moisture and ammonia from gathering. So no gaps as much as possible, and any ventilation must have significant protection to prevent anything from getting in. In this case probably double layered hardware cloth. I'm also considering something like the spike strips used to keep pigeons from roosting as an additional layer of protection around ventilation areas. Those are unpleasant enough to be painful to most things other than a fisher cat. We know the fisher cat can't break through 14 gauge wire that is well secured, it tried to do so with the rabbit hutches and has failed.

The floor of the coop is going to be important for predator prevention. A number of our predators are digging predators including foxes, weasels, raccoon, and fisher cats. To handle those the floor needs to be absolutely secure from digging. The best way to handle that is to have a solid wooden floor with no gaps or concrete. Ideally would probably also have a layer of chicken wire firmly secured to the joists so predators can't even get at the bottom of the floor. Another way is similar to how one handles fences to keep digging predators out, if there is a dirt floor a chicken wire fence under ground down a couple feet with an outward facing L.

Easy to clean and maintain.
We know from previous pet and animal care that if cleaning is difficult it won't be done properly often enough. This means that I will need the ceiling to be at least 6 feet tall through out most of the coop, and any areas that aren't that tall will need to be easily accessible with a rake and or shovel. We will also want to have the floor and at least the lower walls to be some material that is easier to clean than bare lumber. Dirt floor is always a fairly easy choice for this, and can be replaced and re covered more easily than most options. The trick with a dirt floor is that you have to have a good foundation so that the wood doesn't touch the ground where it will be at that wet/dry interface where wood does badly. Concrete is probably the best choice, but I don't have concrete experience.

Not visually awful.
We'd like to have a coop that's relatively visually appealing. We don't really want a rundown shack out behind the house. That mostly just means that I'm going to be shingling and staining it.

Inexpensive, but a good value.
We don't have a lot of money to dedicate to anything, but buying cheap isn't the best option long run. On the up side we do still have about half a bundle of 2x4s and access to pallets. What I am going to be doing to try to minimize the cost is building as much as possible out of 2x4s and pallet bits including building the wall surface inside and outside out of pallet wood. Roofing we will likely be doing with what ever we can find on sale since asphalt shingles or metal roof will both work, it's just what we can find for a better value. I also have to be careful to not spend so much time buying something would have been a better value.

Wants

Electricity
This would allow us to have a heating system inside, a powered water heater to keep it from freezing, etc. I'm thinking something like a boat solar cell system, and a small battery under the roof might be perfect.

A water collection system to feed an auto waterer
For obvious reasons this would be awesome. It shouldn't be difficult to make, gutters, PVC pipe, and a 5 gallon bucket should be sufficient for at least something basic.

Easy to open and close ventilation
It would be nice to have easy to adjust, multiple setting vents that can be gotten at from the outside so we can close them quickly in case of sudden bad weather.
Externally accessible nest boxes
A nice luxury so we don't have to go in to the coop and roust out hens in nesting boxes since they can nip and scratch.
Easy to expand
Apparently chickens are some kind of sick addiction, and everywhere recommends making the coop easy to expand because they're like potato chips.
Storage space
A place in or on the outside of the coop to store food and other chicken needs.

Resources Used

http://www.backyardchickens.com/a/winter-coop-temperatures

This link has good information about caring for chickens in cold weather.

http://www.backyardchickens.com/a/chicken-coop-ventilation-go-out-there-and-cut-more-holes-in-your-coop

An article focused on ventilation and how important it is. Definitely a list of considerations that need to be taken into account.

http://stevebernard.hubpages.com/hub/Top-Ten-Considerations-When-Building-A-Chicken-Coop

Just a good list of considerations when building.

http://www.motherearthliving.com/mother-earth-living/chicken-coop-design-considerations-ze0z1207zsch.aspx
This link is my favorite covering damn near everything I was thinking about with a lot of recommendations and information that I am going to be taking into account for finalizing my design.