Ventilation - what are the basics?

[loopycoops]

Hi everyone!
I'm Richard and new to raising chickens. I live in a relatively cold climate (Tasmania, Australia) and am currently building my first coop.
I've read several comments about the importance of ventilation in a chicken coop, but it's not clear what the basics are.
Can someone please point me in the right direction?
I want to build a movable coop, and plan on having two or three nesting boxes in the coop.
Since it gets cold, I want to design the coop to provide some level of insulation or protection from the cold, but not sure what this looks like when considering ventilation.
Any help would be appreciated!
-Richard

 

[3KillerBs]

Welcome to BYC.

I have to clock in to work in a minute so I only have time for a little quick copy-and-paste that may or may not be directly relevant.

I'm sure others will chime in.

First, define "cold" -- what are your summer maximums and winter minimums? And are you wet or dry?

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.

How to Provide Good Ventilation

There are many ways to provide ventilation in a chicken coop and the ordinary windows that are so often seen on coops, especially those designed to have strong visual appeal, are often not the best choice. As noted in the Usual Guidelines, ventilation is best placed above the chickens' heads when they're sitting on the roost. This is both because heat and ammonia rise and need to escape at the top of the coop and because such ventilation is draft-free.

Wait a minute, what does "draft-free" actually mean?

It doesn't mean total lack of air movement, it means no strong breezes capable of ruffling the birds' feathers and thus disturbing their down-parka insulation. Look at my run-into-brooder conversion: https://www.backyardchickens.com/articles/run-to-outdoor-brooder-conversion.76634/

That's an 8" opening all around the top -- 16 square feet of that permanent, 24/7/365 ventilation we talk about. Even with all the vents open on both ends it's draft-free for little chicks because of the cardboard barrier. Soon that barrier won't be necessary and for adult birds in a warm climate it would never be necessary to pin down the tarps except in blowing rain.

Vents at the top of the wall are easy to make as long as you plan generous roof overhangs. Just don't carry the siding all the way up and cover the gap with hardware cloth. If it's a sloped roof rather than a flat roof be sure to put the vents on the walls at the bottom and top of the slope so that you get a constant flow of air on the underside of the roof to carry the heat, moisture, and ammonia away.

If you're building a peaked roof then plan on leaving out the soffit blocks and either installing a ridge vent, gable vents, or both. Remember that ridge vents are easily blocked by snow and that ventilation is just as important in the winter as in the summer. (See this article on cold weather chicken-keeping).

Monitor roofs and cupolas are traditional means of providing for top-level ventilation that is both draft-free and weatherproof. With sufficient roof overhang they will continue to work despite moderate snowfall (and if your snow is deep enough on the roof to block them you might want to be clearing the roof to protect the structure anyway). The coop page for my Little Monitor Coop includes construction details for framing a monitor, this coop includes a functional cupola, and here you can see how another BYC member mounted a monitor on the roof of a plastic shed.

Top hinged windows are the best windows for providing supplemental ventilation at a lower level because they act as their own awning to protect against rain and can be adjusted to account for different temperatures and weather conditions. Here's one way to make a safe, adjustable prop to keep them open. Sometimes it's good to have a window down low to allow cool air to enter at or near ground level. The top hinge concept works for this too. Since I never need to close mine in this climate I just tucked it under the roof of the nest box.

Remembering that chickens don't stack for storage and thus height can't compensate for lack of floor space, height is your friend when it comes to ventilation. When trying to add ventilation to an existing structure, if the roof is high enough above the roosts you can pull the siding off the gable triangles or open up the soffits and/or the top of the wall. Roof overhangs are also your friends.

Yes, sometimes when you have a very small coop, especially a commercially-made coop, you will realize that getting adequate ventilation means replacing an entire wall with wire. That's one of the reasons why BYC regulars usually advise against using those small, commercial coops -- they are dreadfully hard to ventilate properly. In some circumstances, especially in warm climates, pulling off the wall that faces into the roofed run actually is the right way to solve the ventilation problem.

Adding roof extensions to shelter these vents can be intimidating to inexperienced handymen. Here's how-to (and how not to), extend a roof by sistering the extension to the rafters: https://strousehomeinspections.com/blog/structural-roof-extensions.html

And here is how to use lookouts to extend the roof at right-angles to the rafters: https://www.backyardchickens.com/ar...e-overhangs-eaves-of-a-shed-coop-house.76599/

This member did a nicer job putting awnings up than I did on my brooder: https://www.backyardchickens.com/threads/check-out-my-chicken-tractor.1456418/post-24496139

 

[DobieLover]

Since it gets cold

Define cold. Generally speaking, you don't need to insulate unless you have truly bitter cold winters for sustained periods of time.

My birds went through a winter three years ago where it dipped down to -23F (-30C) and they did fine. This winter has also be a peach. We've had more than the average number of subzero nights. When it gets THAT cold, some frostbite on the tips of combs is inevitable so choosing breeds with tight combs (pea or rose or small single) is a good idea.

You want good air flow in the coop to keep it dry. That is your goal. DRY. Birds emit a lot of moisture during the night from respiration and defecation. That moisture needs to flow out of the coop, not build up.
You want roosting space that is protected from strong drafts. Drafts strong enough to open feathers. Small drafts are okay as that is just more ventilation.

This type of ventilation is achieved by having lots of permanent ventilation up high to release warm moist air and some lower openings to permit the entrance of fresh dry air and promote air flow. One of the best places to put ventilation is under the soffits and in the gable ends.
To keep the coop dry you want large roof overhangs all the way around to protect the openings:

Interior view:

There is a ridge vent too. The areas that show light coming in (except the windows) are all open year round. I have two more windows away from the roosts that I leave cracked open even during winter. There is also a second pop door that is left open year round. It's those pop doors being left open that allow really good air flow through the coop.

I keep no water or feed in the coop. It is all in the attached fully predator proof run. The birds come off the roost in the morning and head right out to eat and drink.

I originally considered a chicken tractor but abandoned the idea because to have the right amount of space for the birds, the tractor would have to be very large and I didn't want to have to haul that thing around un-level ground. If there are gaps around the base of the tractor, it is not predator proof.

 

[loopycoops]

Define cold. Generally speaking, you don't need to insulate unless you have truly bitter cold winters for sustained periods of time.

My birds went through a winter three years ago where it dipped down to -23F (-30C) and they did fine. This winter has also be a peach. We've had more than the average number of subzero nights. When it gets THAT cold, some frostbite on the tips of combs is inevitable so choosing breeds with tight combs (pea or rose or small single) is a good idea.

You want good air flow in the coop to keep it dry. That is your goal. DRY. Birds emit a lot of moisture during the night from respiration and defecation. That moisture needs to flow out of the coop, not build up.
You want roosting space that is protected from strong drafts. Drafts strong enough to open feathers. Small drafts are okay as that is just more ventilation.

This type of ventilation is achieved by having lots of permanent ventilation up high to release warm moist air and some lower openings to permit the entrance of fresh dry air and promote air flow. One of the best places to put ventilation is under the soffits and in the gable ends.
To keep the coop dry you want large roof overhangs all the way around to protect the openings:
View attachment 2998440

Interior view:
View attachment 2998439
There is a ridge vent too. The areas that show light coming in (except the windows) are all open year round. I have two more windows away from the roosts that I leave cracked open even during winter. There is also a second pop door that is left open year round. It's those pop doors being left open that allow really good air flow through the coop.

I keep no water or feed in the coop. It is all in the attached fully predator proof run. The birds come off the roost in the morning and head right out to eat and drink.

I originally considered a chicken tractor but abandoned the idea because to have the right amount of space for the birds, the tractor would have to be very large and I didn't want to have to haul that thing around un-level ground. If there are gaps around the base of the tractor, it is not predator proof.

Wow! Beautiful coop!
Cold, well, usually not below freezing or maybe -2 degrees celsius at most.
I see what you mean about having vents up top.
Should there be an opening further down to let the air in or is ventilation mostly focusing on letting the hot air out?
I'm also not wanting any food or water in the coop, but like you keeping it in the run.
I haven't yet settled the idea whether the coop needs to be totally walled off from the run and have a small door that I can open or close, or just have a large section open.
Hopefully that makes sense...

 

[DobieLover]

Cold, well, usually not below freezing or maybe -2 degrees celsius at most.

That's not cold. Just keep it dry and your flock will be fine. Don't insulate.

Should there be an opening further down to let the air in or is ventilation mostly focusing on letting the hot air out?

It certainly helps with air flow. But if you pair soffit vents with gable and/or ridge vents you will promote air flow too.

 

[U_Stormcrow]

First, the advice by the posters above is excellent. I won't add to it.

Second, if this site is accurate, https://www.climatestotravel.com/climate/australia/tasmania , you don't get cold. Cold for you maybe, NOT cold for chickens.

If your birds are fully fledged, and acclimated, there is no need whatsoever for supplimental heat or insulation. Insulation actually works contrary to ventilation - good idea for climate-controlled human habitation, bad idea for chicken houses.

 

[U_Stormcrow]

If you want mobile, look into "hoop coops", I assume you have some equivalent to a cattle panel available to you on that side of the planet. They are (relatively) lightweight and about as space efficient as you can build. Even then, you are looking at likely a couple hundred pounds, so a small powered vehicle to move them helps, or wheels and a draft animal (yourself, if required). Flat (not neccesarily level), but flat, ground is a really needed to make the best of them.

 

[3KillerBs]

Cold, well, usually not below freezing or maybe -2 degrees celsius at most.

That's not cold for a chicken with it's built-in down parka.

I have an Open Air coop and my chickens have been perfectly happy with nighttime lows down into the upper teens F (-7-8C). As long as they're dry and out of the wind they're fine.

If you get summer highs over 90F (32C), you'll have more problems with heat than with winter cold.

 

[Egghead_Jr]

All Livestock need ventilation. From cows to chickens. The idea is to keep your barn, stable or coop dry and draft free. Top venting is the way to go and if in very hot climate large wall openings covered in hardware cloth.

Animals create a lot of moisture. Heat rises and so will that excess moisture ridden and ammonia filled air. 1 square feet of venting per chicken is for passive venting. If you use convection venting it's minimal by comparison. The easiest way to accomplish proper convection venting is to design a single slant roof of 4/12 or 5/12 pitch. Have small openings along the top of wall under bottom and top roof slant. Or you could leave the 2x3 or 2x4 rafter spacing open covered with hardware cloth to keep predators out. That's far more vent than you need but easy to accomplish.

In a nutshell with that pitch of roof the natural sucking in and pushing out of air (convection) will be the proper velocity to mix with stale and wet coop air along roof line and push it out. Too steep of a pitch will create a curtain of air flow that won't mix well. And of course too flat of pitch reduces flow of fresh air needing larger openings. Like using the rafter opening size is needed. In reality the size of openings needed with proper pitch is 1" drilled hole per linear foot. Number of birds, size of coop and other factors would determine the mathematical (yes there is a calculation) minimum opening size needed. I say this just to give you an idea of how little openings are needed to ensure a dry coop. Keeping to the minimal side is preferred by me as I'm in a cold climate and want to retain some of the heat generated by the birds. You being in a warm zone, not hot but certainly warm for livestock have no concern of minimal venting and should think moderately to compensate for summer.

With coop door open days and not caulking your joints there is plenty of air being drawn in without adding a lower vent.

 

[Sally PB]

Nothing to add, except to say good for you, for thinking ahead on one of the most important concepts of coop design.