ventilation for 8x12 shed

We are building a 8 x 12 (height almost 7.5 ft) shed for around 30 cornish cross. I am trying to figure out ventilation. Is there a formula to how much ventilation and where should the vents (windows) be in the middle of the walls, the floor, towards the top?

One answer to "how much" is one sq ft of ventilation per chicken. There is an excellent article linked in my sig line that discusses this and related matters.

Welcome! That will be tight for 30 meat birds; have you considered a movable hoop coop instead? That way you move it across the grass every couple of days, rather than shoveling out the huge amount of poo produced, and they have really good ventilation at very low cost. A building will need large openings in the peaks, big windows, and a big window in the door, all covered in hardware cloth. Probably a fan or two also; still air won't be good. Mary

Judy gives a rule of thumb for this.

using her method you would need 30 sq. ft. of vent, sometimes that may be impractical from an available wall space perspective.

Air Flow is what vents provide, so for 30 Sq. Ft. of vent ( 15 per side wall, opposite each other) you could still have stagnation of the air occur. Vents should be placed so that the natural winds in your area are going to hit the vents and so pass through the coop and out the other side. You may find that you need even more than 30 sq. ft. if you don't have much wind blowing. This is when some small fans could be really handy to have installed to create air flow.

Vents are best up high, windows are great and you would place them so the chickens can look out when they are on their roost.

Our coop is 8' w x 8' l x7.5' h there are two vents at the roof line, 12" high by 8 feet long. These are set to the prevailing wind direction. There are, in the same walls, two 2' x 2' windows set at 5' from the ground (coop sits 12" off the ground at the lowest point).
I have been inside when no wind blows and it is comfortable even at high noon. But, our coop sits in a shaded area, and has a highly reflective white metal roof over 7/16" OSB sheathing with 30# felt. Our prevailing wind is usually around 10-15 mph.

Fans can be 12 volt or 110 volt depending on your electric set up, they only need to be on one wall, facing the other vent side.

something that will help with ventilation is make sure you vent the ridge of the roof, and under the eaves/top of the walls. That way even if you have no prevailing wind to work with, you get a chimney effect that will draw air in, as the air warms, it rises to the the peak of the roof and out through the vent system. you could actually even put a chimney on the roof. I do believe this was originally the reasoning behind putting a cupola on a barn......

you can buy a ridge vent specifically made for shingled roofs, I had the roofers put it on a house I built and it worked great. Or you could put turbine type vents on the roof to help pull air through if you don't have enough wall space to get the recommended square footage, proper ventilation is all about air flow anyway, get the heat out in the summer, and the moisture out in the winter

There can never be enough venting. Flexibility is the key. So you can control depending on the season, wind direction, etc. I use gables vents with shutters and windows on every side possible.

Recommended ventilation is 1 sq ft per bird. But in Realville, MORE is always better. For your coop, a ridge vent would be a good start. But what it really needs, is for about 3' of hardware cloth screening all the way around the bottom half of the walls, including the door/doors. 30 birds in that space, is going to need LOTS of fresh air flow. You could have hinged panels that would swing up and uncover, and cover, the screened part of the walls. That would also make for a good rain shield for the open screened walls. You do this, and you should not have to mess around with any fans.
Some people think that the ventilation has to be up over the chickens heads. There is nothing wrong with ventilation right at chicken level. The whole front wall of my coop is wire, right at bird level. The wall is left wide open year round, and the birds thrive.

JackE said:

Recommended ventilation is 1 sq ft per bird. But in Realville, MORE is always better. For your coop, a ridge vent would be a good start. But what it really needs, is for about 3' of hardware cloth screening all the way around the bottom half of the walls, including the door/doors. 30 birds in that space, is going to need LOTS of fresh air flow. You could have hinged panels that would swing up and uncover, and cover, the screened part of the walls. That would also make for a good rain shield for the open screened walls. You do this, and you should not have to mess around with any fans.
Some people think that the ventilation has to be up over the chickens heads. There is nothing wrong with ventilation right at chicken level. The whole front wall of my coop is wire, right at bird level. The wall is left wide open year round, and the birds thrive.

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I whole heartedly agree with you on this issue I also believe that you can always add more at any time. The low to high ventilation method has been around ever since people started living in buildings. I always start with the high vents then add lower vents until I have the best airflow I can muster with out fans.

Hello all,

On the subject of ventilation i planned ahead on my 6 ft. x 12 ft. x 7.6 high run.
I purchased online a "fancy 'cape cod' style coop' which i feel is too small for the 4 hens i have but provides a secure night time roost area and attached nest box.which are all 24 inches above ground with a hardwear cloth underside which in find useful when i clean the run so the girls can still drink and eat. this area i normally keep opened.

You all pointed out that 1 cu.ft per bird is acceptable but i added a 12 volt marine blower fan (avail. in 3" dia. or 4" dia).

I added a switch,fuse and wave runner/snowmobile SEALED battery for power. My fan moves 270 cu.ft.of air per minuite so i turned it outward as an exhaust draw.

The result is a great form of airflow OUT of the coop at roost level.
I have an 18 inch rafter set up for my roof with 2" hawk proof netting over the ENTIRE structure BEFORE building the roof.
SECURITY FROM PESTS
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For security i also use a 6 wire electric garden fence , activated at dusk, to protect from raccoons and possums. It has also KILLED a rat which strayed across the lowest wire,2 " off the ground.( you MUST keep ALL growth CLEAR of the lower wires to prevent grounding.

The fence is a simple 'garden/pet fence' which sets up in 10 minuites. buy a tester as well to check activation of the fence. The entire set up costs $69.00 for the fence and $3.00 for the tester.
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I employ drop down run panels for my run due to our heavy rain/wind combination. These lock both down and up as well. I can lower the sun facing side for a little shade.
INSECT/ODOR control
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Farm360 is a natrule enzime spray/drench for the poop areas. I do prefer hay as the chickens love to discover things under it. I CHANGE THIS DAILY!!! DO not let it stay down-it WILL mould.
I also use 4 Oz. bleach to 1 gal of water for cleaning poo from the surfaces i need to scrub. RINCE WITH CLEAR WATER AND RUB WHILE DOING SO to remove the bleach and spray with farm360.

all together the coop cost $800.00 to build from pressure treated wood,including all hardwear and fencing and fan ect.as well as the feed,hat,feed and water containers.

My birds cost is low comparitively.
I has an isbar, a leghorn cross, an americauna and a french hen( maran cross ).All are 2-3 months old.

Perhaps some of this info can provide ideas for others.