# ventilation square footage to bird ratio?

Discussion in 'Coop & Run - Design, Construction, & Maintenance' started by Puck-Puck, Apr 20, 2009.

1. ### Puck-PuckChillin' With My Peeps

Pat & Chickens,
I have read your excellent ventilation page, and it has taught me lots of things. But in case you thought it was idiot-proof... I volunteer to be the idiot!

Is it possible to make a simple ratio of "ventilation square footage : chicken", or is that too dependent on temperature, humidity, prevailing wind speed and direction, and planetary transits?

I have a shed on the property which I am considering converting (back?) to a chicken coop. It is 5' x 11', and the entire edge of the roof is passively vented, as the metal roof is resting on a grid of 2x4s which allows for free air circulation. It is no big deal to add more ventilation in the gables, and build a little indoor roof over the roost to prevent down-drafts, but I am just wondering (on everyone's behalf) if there is an actual formula.

Thanks!

2. ### patandchickensFlock Mistress

Apr 20, 2007
Quote:LOL. Extra points for style

Is it possible to make a simple ratio of "ventilation square footage : chicken", or is that too dependent on temperature, humidity, prevailing wind speed and direction, and planetary transits?

"Yes"

?

OK, if pressed -- based on a bunch of things, including but not limited to various chicken husbandry books, I'd suggest you want to be somewhere in the range of 0.3-1.0 sq ft of ventilation opening per chicken. (That is actually free air space; those louvered thingies they sell for sheds and attics often have far, far less actual air space than the total area of the louvered vent as a whole)

But that is a generic answer not taking into account the sorts of factors you mention. In a hot climate I would for sure go higher than this. I would not suggest going lower; some people can get away with less, but you won't *know* whether you're one of them til the coop is built and being lived in, and it is EVER so much easier to have more ventilation than you need than need more than you have.

In particular, bear in mind that small holes offer a lot more air resistance than big ones; so a 12"x12" opening will allow greater airflow than 144 1x1" holes.

So, you could kind of do some quick math on your shed, see what realm the existing openings put you in. I forget where you're located but bear in mind that if you get cold weather (like towards freezing or below) you are likely to want to insulate that metal roof, to prevent condensation (which decreases the effectiveness of whatever ventilation you've got, b/c water condensed out as droplets or frost is not available to be whooshed out the vents the way water *vapor* is).

So I dunno if that helps, but that's the best I can tell ya

Good luck, have fun,

Pat​

3. ### Hillbilly RoosterChillin' With My Peeps

Apr 16, 2009
Middleville, Michigan
I put in a bathroom exhaust fan with a switch so when it is hotter than normal and the hens want to be in to lay I turn it on.

4. ### patandchickensFlock Mistress

Apr 20, 2007
The thing about bathroom fans is that they are not designed to work in a high humidity/high dust area, and tend to experience short lifetimes (even if blowing *into* rather than out of the coop, which is less dusty) and can be a fire hazard.

Honestly, I'd argue it is far FAR better to just build in sufficient passive ventilation in the first place (i.e. openings in walls). Cheaper in the long run, not dependant on electricity, and never a fire hazard.

JMHO,

Pat

5. ### Puck-PuckChillin' With My Peeps

Pat & Chickens,

Thank you for your reply! I was hoping it would be something easily calculatible like that. I get your point about larger, and extra, openings. And yes, it went down to -30 C here this winter. Brrr!

I would have thanked you sooner, but we had *AHEM, HILLBILLY ROOSTER* a power outage, most unexpectedly of course, so I was only able to read your reply just now. Another good thing about passive ventilation--power outage proof!

Puck-Puck

6. ### Hippie ChickieChillin' With My Peeps

Mar 24, 2009
Port Orchard
Pat thanks so much, My DH was telling me today about his planned ventilation and I kept telling him that it wasn't enough. Bassically just the roof gap like Puck-Puck's. Now I can give him some hard numbers. Awesome! I love your ventilation page btw.

7. ### gentlemanfarmerOut Of The Brooder

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Jan 31, 2009
Northwestern PA
Just finished building my coop. I have 2 2x3 windows that hinge out with hardware cloth over the inside on northeast and also 2 on the southwest side. I also have hardware cloth over the sofit about 8" wide. I live in western PA is this enough? What about winter, when the windows are closed? I have 12 buff orpington chick that will live in there and also 24 cornish X which will be gone by late July.

8. ### farrier!Chillin' With My Peeps

Feb 28, 2009
Southern Illinois

9. ### Puck-PuckChillin' With My Peeps

Farrier, just scroll back up this page to Pat & Chickens' post. In her actual post, at the bottom, is a blue Ventilation Page link.

(You can probably also get there by going to Members List, looking up Pat & Chickens there, and hitting on her BYC page link there.)

Apr 20, 2007