How much ventilation does a small coop need?

[JuliaSunshine]

I'm building 4X4X2.5 coop and the ceiling will be covered with hardware cloth and a metal roofing.
I think there will be some gaps between the hardware cloth and the corrugated roofing.
But I'll need to add more ventilation on the walls.
The front and the back wall will be solid wood with no window or ventilation.
I'm going to cover the left and right wall with hardware cloth and cover them with plastic (I'll take the plastic off when it's hot).
For ventilation, I can just not cover a few inches on the top of the two side walls with plastic.
How many inches should I leave open from the top of the walls (but still covered with hardware cloth)?
1 or 2? Or 4?
The perches will be 0.5 foot off the bottom of the coop. My chickens are average size.
The winter here is on the mild side. The temperature goes down below freezing not that often and when it was the coldest in decades last year it was 12F. It just rains a lot and cloudy.
Thank you!

 

[U_Stormcrow]

Before I open my mouth and insert foot (which would really affect the taste of the coffee), feet, or meters???
You say inches, below, and .5 foot, but that's a very small coop. How many birds are you planning???

 

[U_Stormcrow]

OK, coffee done. Going to see how the foot tastes. Using "thumb rules" here, I don't know the adjustments for your climate.

That's 16 sq ft, which thumb rules say is four birds. Four birds need four square FEET of ventilation, 24/7/365 as a passive airflow guideline. You have 16 linear foot of perimiter, so you need 3-4" opening all the way around (your corners will intrude into that space - if its a 2x4 consturction, you lose about 5" linear per side, 2x2, 3" - small enough to disregard). You can't count your "window walls" because they will be covered some of the time, and will put drafts directly on the birds. Drafts you DEFINITELY don't want.

Basically, you want the wide face of a 2x4 all the way around at the top in terms of free airflow. and depending upon the strength of your winds, and the overhang you are willing to build, that may still allow considerable windblown rain/snow into one side of the coop. With a roosting bar 6" off the ground, a height of 30", a need for (minimal) roof framing, plus a large gap for airflow, you don't have much of an interior envelope for your chickens to be sheltered in.

Have you serously given thought to going bigger? Not necessarily a lot, but certainly "some". 6" more height would help. What's your roofing plan? (metal, wood, polycarbonate, reused/repurposed palletes, etc). Are there other constraints we need to work around?

Do you plan on a covered run? What's your intended flock size? For the system to work well, everything needs to work together.

 

[JuliaSunshine]

OK, coffee done. Going to see how the foot tastes. Using "thumb rules" here, I don't know the adjustments for your climate.

That's 16 sq ft, which thumb rules say is four birds. Four birds need four square FEET of ventilation, 24/7/365 as a passive airflow guideline. You have 16 linear foot of perimiter, so you need 3-4" opening all the way around (your corners will intrude into that space - if its a 2x4 consturction, you lose about 5" linear per side, 2x2, 3" - small enough to disregard). You can't count your "window walls" because they will be covered some of the time, and will put drafts directly on the birds. Drafts you DEFINITELY don't want.

Basically, you want the wide face of a 2x4 all the way around at the top in terms of free airflow. and depending upon the strength of your winds, and the overhang you are willing to build, that may still allow considerable windblown rain/snow into one side of the coop. With a roosting bar 6" off the ground, a height of 30", a need for (minimal) roof framing, plus a large gap for airflow, you don't have much of an interior envelope for your chickens to be sheltered in.

Have you serously given thought to going bigger? Not necessarily a lot, but certainly "some". 6" more height would help. What's your roofing plan? (metal, wood, polycarbonate, reused/repurposed palletes, etc). Are there other constraints we need to work around?

Do you plan on a covered run? What's your intended flock size? For the system to work well, everything needs to work together.

Thank you for your advice and concern.
I'm going with the same size though as I've already started on making the frame and I'm following Justin Rhodes Chickshaw style with a few modifications which has a lot of open wall and bottom space. His chickshaw is 4X4X2 feet.
But I'll consider lowering the roosts to give them more head space as you suggested. I'm going to have a poop board and clean it every day.
My 10 chickens free range all day on a few acres of forest/pasture setting without fence and they can go into a few sheltered places as they please. But they tend to stay outdoors even in the rain. They're using the current open concept 6X8X8 feet coop just for sleeping but I got worried they might get too cold in the winter. so I decided to make another one smaller so they can stay warmer at night.

The metal roof of the new coop will be flat with enough overhang or I might cover the area where the coop will be with a tarp.

I'll think more about ventilation and draft in a coop. I wonder if a draft is always bad, how an open concept coop like Chickshaw works. Its walls are open all the way from the bottom to the top and the floor is just hardware cloth.
I don't think my climate is colder than his.
I might be better off having ventilation vertically like his Chickshaw not just at the top.
I'll look into how open concept coops work.
Thank you again for helping me think more about it.

 

[U_Stormcrow]

The chicksaw coop concept is similar to the woods style coops, in that it counts on particular ratios to create a dead air buffer on the three enclosed sides. and the chicksaw is the size it is to make it human movable over irregular terrain in the way a coop built on, say, my 4x8 alum frame trailer would not be (though an ATV would be more than adequate to the task, or a real lawn tractor/rider mower. Open air coops (and adirondack shelters) all share similar concepts - when air is blown in, having no place to go, pressure builds, which then buffers further efforts of the wind to blow in.

 

[JuliaSunshine]

The chicksaw coop concept is similar to the woods style coops, in that it counts on particular ratios to create a dead air buffer on the three enclosed sides. and the chicksaw is the size it is to make it human movable over irregular terrain in the way a coop built on, say, my 4x8 alum frame trailer would not be (though an ATV would be more than adequate to the task, or a real lawn tractor/rider mower. Open air coops (and adirondack shelters) all share similar concepts - when air is blown in, having no place to go, pressure builds, which then buffers further efforts of the wind to blow in.

Oh the last part you said is really good to know! I've been wondering if having some part of the side walls open, from the bottom to the top, would be better than having the top few inches open as there isn't much head space and the wind right above chickens' heads probably will keep blowing in and out taking away any heat generated from them.
I'll probably use the open air concept instead of the traditional ventilation on the top.
I'll place the coop next to a building near forest so it'll be sheltered, too .
Thank you again!

 

[3KillerBs]

Here is my article on coop ventilation: https://www.backyardchickens.com/articles/repecka-illustrates-coop-ventilation.77659/

The Usual Guidelines

For each adult, standard-sized hen you need:

• 4 square feet in the coop (.37 square meters)
• 10 square feet in the run (.93 square meters),
• 1 linear foot of roost (.3 meters),
• 1/4 of a nest box,
• And 1 square foot (.09 square meters) of permanent, 24/7/365 ventilation, preferably located over the birds' heads when they're sitting on the roost.

I'm building 4X4X2.5 coop

4'x4' is enough for 4 chickens. 2.5 is too low to allow the perches to be above the nests and the ventilation to be above the chickens heads when they're sitting on the roost.

This coop is designed to exactly meet all the minimums for 4 chickens -- it's 4'x4'x4'. https://www.backyardchickens.com/articles/the-little-monitor-coop.76275/

The perches will be 0.5 foot off the bottom of the coop.

This doesn't seem to me to be enough to permit any reasonable depth of bedding and is almost certainly not high enough above the nests to keep the birds from sleeping in the nests.

In this photo the depth allotted for the bedding is 6 inches, the nests are 12" tall, and the vents are 12" above the roost.

I'm following Justin Rhodes Chickshaw style with a few modifications which has a lot of open wall and bottom space. His chickshaw is 4X4X2 feet.

Justin Rhodes' Chicksaws have been developed for a very specific management system that ABSOLUTELY DEPENDS on your ability to open the coop at dawn, no matter how early dawn is, and to close it at dusk. It has absolutely no forgiveness or flexibility for anything other than perfect consistency under perfect conditions.

But I'll consider lowering the roosts to give them more head space as you suggested.

As I said above, they're already so low that you'll end up with birds sleeping in the nests.

My 10 chickens

10 hens should have at least

• 40 square feet in the coop, 5x8, though 6x8 would be more economical of lumber if you buy 12 foot boards and cut them in half.
• 100 square feet in the run,
• 10 linear feet of roost,
• 3-4 nests,
• And 10 square feet of ventilation, best located above the birds heads when sitting on the roost.

This article explains why these numbers are guidelines, rather than hard-and-fast RULES, but I would think long and hard about the disadvantages of putting 10 chickens into a space appropriate for 4. https://www.backyardchickens.com/articles/how-much-room-do-chickens-need.66180/

 

[aart]

Do you get a lot of snow?
What are you temps in winter?

Chicksaws are used in southern climates.

 

[JuliaSunshine]

Do you get a lot of snow?
What are you temps in winter?

Chicksaws are used in southern climates.

I don't get much snow and the temp only occasionally goes below freezing.

 

[JuliaSunshine]

Here is my article on coop ventilation: https://www.backyardchickens.com/articles/repecka-illustrates-coop-ventilation.77659/

The Usual Guidelines

For each adult, standard-sized hen you need:

• 4 square feet in the coop (.37 square meters)
• 10 square feet in the run (.93 square meters),
• 1 linear foot of roost (.3 meters),
• 1/4 of a nest box,
• And 1 square foot (.09 square meters) of permanent, 24/7/365 ventilation, preferably located over the birds' heads when they're sitting on the roost.

4'x4' is enough for 4 chickens. 2.5 is too low to allow the perches to be above the nests and the ventilation to be above the chickens heads when they're sitting on the roost.

This coop is designed to exactly meet all the minimums for 4 chickens -- it's 4'x4'x4'. https://www.backyardchickens.com/articles/the-little-monitor-coop.76275/



This doesn't seem to me to be enough to permit any reasonable depth of bedding and is almost certainly not high enough above the nests to keep the birds from sleeping in the nests.

In this photo the depth allotted for the bedding is 6 inches, the nests are 12" tall, and the vents are 12" above the roost.

Justin Rhodes' Chicksaws have been developed for a very specific management system that ABSOLUTELY DEPENDS on your ability to open the coop at dawn, no matter how early dawn is, and to close it at dusk. It has absolutely no forgiveness or flexibility for anything other than perfect consistency under perfect conditions.



As I said above, they're already so low that you'll end up with birds sleeping in the nests.



10 hens should have at least

• 40 square feet in the coop, 5x8, though 6x8 would be more economical of lumber if you buy 12 foot boards and cut them in half.
• 100 square feet in the run,
• 10 linear feet of roost,
• 3-4 nests,
• And 10 square feet of ventilation, best located above the birds heads when sitting on the roost.

This article explains why these numbers are guidelines, rather than hard-and-fast RULES, but I would think long and hard about the disadvantages of putting 10 chickens into a space appropriate for 4. https://www.backyardchickens.com/articles/how-much-room-do-chickens-need.66180/

Thank you for your concern.

I know some people are happy with their Chickshaw so I'm going to give it a try and ventilation will be through the side walls not the top.

I'm aware of the general rules regarding space and already have a coop big enough for them with 4 nesting boxes which they could use if there's a problem with a new smaller one. Or I could make another one. The nesting boxes will be lower than the roosts and they can be blocked at night.