ventilation.

[fostermom55]

How do you know if how much ventilation you need? I have 5 chickens that roost in a roughly 3' x 5' coop. I haven't been shutting their little entrance door so air can enter there. I am considering caulking the corners, but am still confused, drafts vs. ventilation? I am considering making an insulating "blanket" to put over the entire coop at night. but not sure. after reading other threads have decided not to heat. Still trying to figure all this out! In the warm weather the coop has a 12" x12" window I leave open. but I have closed it now to help hold in the heat. Any comments or advice appreciated! In Maryland!

 

[redsoxs]

Hey, fostermom55. That's a great question. I've always heard the same thing...."make sure your coop is ventilated." Never really considered how much is enough and how much is too much. I typed 'how much ventilation' into the BYC search box and several old threads came up. Maybe you can lean some information from them. Best wishes https://www.backyardchickens.com/newsearch?search=how+much+ventilation

 

[Folly's place]

Holding in the heat will also hold in the moisture, not good. You already have a very tiny crowded space! Pictures will help here, but upper openings covered in hardware cloth are best. Look at the Woods coop designs, for example. Mary

 

[aart]

Welcome to BYC!!

Ditto that pics would help...and also knowing your climate.
Putting your location in your profile helps folks give better answers/suggestions.

Here some good info on ventilation to peruse:
https://www.backyardchickens.com/t/1048597/ventilated-but-free-of-drafts

This is a great video, tho the roost in that coop is way to close to ceiling.

There is also 2 good articles on Space and Ventilation linked n my signature.

 

[Howard E]

Ditto on what others have said. Old school rule of thumb was 1 sf of vent space per 10 sf of floor space, and that was the minimum. The Woods coop, which sets the standard for ventilation has at least double that just from the south side opening alone. More like 3X to 4X that when all the doors and windows are open. I was in mine this morning....the wind was blowing about 15 mph and had things dancing. But inside, at the back where the roosts are, it was nearly dead calm. That is the goal.

The deal with warm coops runs counter to everything we have been taught as far as our own housing is concerned. First and foremost, if the birds are well fed and are acclimated to the cold, they can fend for themselves just fine. No different than the wild birds on the other side of the wire do. Our birds already have insulation in the form of feathers.......same as the wild birds do.

With chickens, a tight coop is a cold coop. The culprit is moisture and the source of the moisture is the birds themselves.....and that mostly from their breath. Their respiration rate is roughly 8X what ours is and with each breath they take, they exhale CO2 and moisture. All that extra moisture makes things damp from condensation and damp is cold. So the flip side is a dry coop is warm and a well ventilated coop is dry. The trick is in building it in such a way that you can have wide open ventilation but still avoiding drafts. The main reason insulation is ever used is to minimize the amount of condensation that occurs in winter and to deflect summer sun and heat.

So lots of windows and open ventilation on the side facing south to the winter sun and closed off on all the other sides to avoid cross breezes and the cold northerly winds. The warm winter sun shining in helps the birds a little, but mainly serves to raise the temp inside relative to the outside, and that dries things out.

 

[fostermom55]

Thank you ! This is what I needed to hear! Very helpful!

 

[Ridgerunner]

I agree, photos could help with us making specific suggestions but knowing your general location to give us an idea of your climate would really help.

The biggest risk in cold weather is frostbite, which can possibly happen anytime the temperature drops below freezing. But some people in Alaska and Canada keep chickens without adding any heat and have no problems with frostbite. Some people in the southern USA where it doesn’t get that far below freezing have frostbite problems. As others mentioned moisture in the coop is generally the culprit, not the actual cold.

Another possible issue is wind. Chickens keep warm by trapping tiny air pockets in their down and feathers, just like the wild birds. If a breeze strong enough to ruffle their feathers hits them they can lose that insulating effect. People often talk about drafts on here as being bad. People tend to think of drafts like they have in their houses where you hold a candle near a closed window or door to see if you are getting any air movement. That’s not the kind of drafts we are talking about. Gentle air movement is good, that means bad air is being replaced by good air. You don’t want a breeze. Sometimes, especially with a small coop, we can create a wind tunnel where any breeze just blows through the coop. This you want to avoid.

To me the easiest way to allow air exchange without having a breeze blow directly on the birds is to have openings above their heads high enough so any breeze just blows over their heads while they are on the roost. If a breeze is blowing outside you get good air exchange. If it is dead calm you still get air exchange because warm air rises. There are different ways the air inside a coop could be warmer, mostly because of the birds themselves. It’s usually enough.

I don’t have any hard and fast rules for how much openings you need. Howard’s rule of thumb is as good as any. People use gable vents, roof vents, or areas under any overhang at the top of the walls to provide openings. Those small elevated coops especially can provide challenges because they often don’t have a lot of height to work with. But each coop is different.

Howard, I certainly agree the Woods design works great, even in Canada. But how well do you think it would work on a 3’ x 5’ coop? Is that coop big enough for the concept to work? I don’t have any experience with the Woods coops but from several of your posts it sounds like you do. It seems to me that you need a certain size for that to work but “it seems to me” doesn’t mean nearly as much as actual experience.

 

[Egghead_Jr]

The minimum of air circulation for chickens is 0.5 cubic feet of air per bird per minute. I've actually designed a coop around that flow rate and can say it's perfect for clean air but not enough flow to rid coop of all moisture in winter so would result in excessive frostbite on cock combs. More is certainly better and being a volume of flow rate not easily measured but that is the minimum for edification.

Air circulation is not directly proportionate to opening size. How ventilation is configured, passive vs. convection air exchange is far more important than actual wall opening sizes. Drafts are a no no but air flow is a definite yes. The easiest way to make for air exchange without drafts on animals is to have openings on top and bottom of a single slant roof. If gabled then openings on each gable end and along each soffit. There should be enough space above the roosts that the birds are not in this air exchange area. Cold air sucks (literally pulled in via convection) on low end, mixes with the hot moist coop air about 6 inches to foot depth along the roof line (depending where holes are located) and is pushed out the top vents. SIngle slant roofs at 30 degree angle are the most efficient for ventilation.

The woods coop design is passive air exchange. The southern wall is all open screen, the roosting area is on North wall far enough back not to have drafts. Takes a large coop and in reality is the equivalent to a small well vented coop with covered run and tarps for wind shield on two or three sides during winter.

Here's an example of how easy this all can be if you've a small coop. My current layer coop has hardware cloth over the entire top over rafters so weasels can not get in. No sheathing over that just tin roof screwed to the small 2x2 rafters. The high hat of roofing is the ventilation. Simple and very effective.

 

[Egghead_Jr]

You can use an auger drill bit or even hole saw to make holes along each end of roof line. 1" minimum hole size and I'd not go much over 2 inch hole saw depending on how low your roosts are. That or even cut the sheathing or build to leave the sheathing an inch or two below the roof line and cover with hardware cloth.

Where the angle of roof comes into play is the circulation of coop air to outside air. 30 degree is optimum as it pulls the air in fast apposed to a lesser pitch and provides enough time for that air to circulate with coop air before exhausting out the top vents. Too much of a pitch and the air wont circulate as much. Basically I can smoke a cigarette at the low end of roof and watch the smoke get drawn into coop but not see smoke exit other end as it's been mixed so completely with coop air along the roof line. A 45 degree or more pitch and you'd see smoke come out top line as it didn't have a chance to circulate. A flat roof doesn't draw the air in as readily.

 

[Howard E]

Howard, I certainly agree the Woods design works great, even in Canada. But how well do you think it would work on a 3’ x 5’ coop? Is that coop big enough for the concept to work? I don’t have any experience with the Woods coops but from several of your posts it sounds like you do. It seems to me that you need a certain size for that to work but “it seems to me” doesn’t mean nearly as much as actual experience.

3' x 5'? That seems pretty small. On another thread, I proposed plans for a smaller Woods coop in the range of 4' x 6.5'. The Woods "mini".........

https://www.backyardchickens.com/t/1131864/woods-house-mini

As noted, JackE voted against going that small. I am aware that Woods said in his book not to mess with his designs as they were carefully thought out. What I also note is he himself scaled the design up and down in size, but always kept things in the same proportions. Woods smallest design, intended for small backyard flocks like ours, was 6' x 10'. That was designed for up to 12 birds, but 4 or 5 or 6 would do well in it.

My thoughts are on the mini, as long as you kept the right proportion, it might work. Woods houses are rectangles with small side facing into the winter sun. The proportion of the rectangle is the long side (depth) is 1.6x to 2x the width, with roost bars along the narrow side to the far back. The long sided rectangle is what creates the dead pocket of air in the back. Woods called it an "air cushion" or some such thing. I have hung flagging tape streamers in mine and have watched them in the wind. There is some turbulence at the front, but it decreases from front to back, with streamers in the back barely moving at all. I note the same thing happens in the attached shed of our horse barn, which is a long narrow rectangle, open side on the narrow leg. A lot of air movement at the opening, but it immediately calms down as you move back into the shed.

What you do want to avoid is to avoid changing the proportions. The height to width proportions, nor the back part deeper or more shallow, or changing the shape and proportion of the front scratch shed.

In reality, a Woods house is more run than coop. It is essentially a covered run that has three sides mostly enclosed, but one side wide open for light and ventilation. The angles of the roof lines and position of the window openings set to allow the light from the winter sun to shine in all the way to the back. If you look at it like that, there is no advantage of my 4' x 6.5' mini, with run, over the 6' x 10' Woods coop. They have the same overall foot print.