Chicken coop roof pitch: How to determine the right slope for your coop’s roof
When DIYing your chicken coop, a crucial step is to get the correct angle for the slope of your chicken coop roof. If the slope is too small or too large, your roof won’t last very long, or it will need a lot more reinforcement.
The terms “angle,” “incline,” and “slope,” can all be used interchangeably, but the technical term is “pitch.”
So, what is the correct pitch for a chicken coop roof? A chicken coop roof needs to have a minimum pitch of 3:12 or 14° in most climates. For climates with heavy snow loads, a chicken coop roof needs to have a minimum pitch of 4:12 or 18.5°.
In this article, you will learn everything you need to know to determine the pitch that is right for your chicken coop. I’ll cover the following topics:
Why you don’t want a chicken coop roof that’s too flat
A flat roof comes with a few different problems. First, flat roofs won’t last as long because rain and snow will pool on top of them. This may cause rotting of the roofing material, and may cause the roof to bend, warp, or even buckle.
Many chicken coop roofs have caved in when built at a pitch that was too flat.
If you feel you must build a flat roof on your coop, you will need to properly reinforce it underneath with several rafters. You’ll want to use thicker rafters and more rafters spaced more closely together.
Another problem with a roof that’s too flat is that your chickens may start to roost on it. This means you’ll need to clean chicken poop off the top of the roof, which is never convenient.
You may also have the problem of your chickens wanting to roost on the roof at night, rather than going into the chicken coop. You’ll have to wrangle them off the roof and into the coop each night.
Why you don’t want a roof that’s too steep
If you build your roof at a very steep angle, your chicken coop will be incredibly tall. This can be more difficult to build. You’ll need much more roofing material.
You’ll also need to more strongly reinforce a very steep and long roof with extra roofing nails and more rafters underneath.
What is roof pitch and how do you calculate it?
Roof pitch is the slope of the roof.
Roof pitch is expressed in a couple of different ways. You may see it referred to as the angle between the roof and the horizontal. More commonly, you’ll see it referred to as the rise of the roof over the run of the roof.
The image below illustrates these two concepts:
Roof pitch that is expressed as rise over run is typically presented as a ratio. You will see roof pitch referred to as x:12, where x represents one unit of rise for every 12 units of run. You may also see the ratio written as x/12. The ratio is spoken as “x-in-12” pitch or just an “x pitch.”
That sounds a little confusing at first glance, but it’s quite straightforward. For example, say you have a chicken coop roof with a pitch of 3:12. This is a “3-in-12 pitch” or a “3 pitch.” This means that for every 12 units of roof run, the roof has increased 3 units in height. For this example, I’ll use “ft” for units. Check out the illustration below:
Note that because pitch is a ratio, the units you use don’t matter as long as they are the same for rise and run. I used feet above, but I could just as easily have used centimeters or inches.
According to Omni, roofs can be divided into four categories, based on pitch:
Flat roofs have a pitch between ½:12 and 2:12
Low pitched roofs have a pitch between 2:12 and 4:12
Conventional roofs have a pitch between 4:12 and 9:12
High-pitched roofs have a pitch above 9:12, some as high as 21:12
As you’ll see in the next section, most chicken coop roofs are low-pitched or conventional, based on this classification.
What are the angles of slope that correspond with some of these pitches? Check out the table below:
| Roof pitch (rise over run) | Roof pitch (angle) |
|---|---|
| 2:12 | ~9.5° |
| 3:12 | ~14° |
| 4:12 | ~18.5° |
| 9:12 | ~37° |
| 12:12 | ~45° |
| 21:12 | ~60° |
How to choose the pitch for your chicken coop roof
For most climates, the minimum pitch you’ll want for your chicken coop is 3:12. If you live in a dry climate with very little rain or snow, you could probably get away with a 2:12 pitch.
If you live in a climate with heavy snow loads, you’ll want your roof to be a bit steeper, at least 4:12.
When you buy roofing material, always make sure to check what the packaging says. Some materials will tell you the minimum pitch required for that material. For example, most Ondura roofing says to use at a 3:12 pitch minimum. Some asphalt can be used at a 3:12 pitch, but other asphalt requires extra support and materials if used at pitch that low.
For more on chicken coop roofing materials, check out my article, Chicken Coop Roof Options: What’s the Best Material?
Use your chicken coop roof pitch to calculate the amount of roofing material you’ll need
You can use your roof pitch to calculate the size of your roof in two different ways: the mental math way or the online calculator way.
Roof pitch mental math
If you want to use mental math, follow these 4 steps. Make sure to check out the example below for clarification.
Choose your roof pitch. Remember, you want a minimum pitch of 3:12.
Determine the rise of your roof. Multiply the length of the coop side (i.e., the run of the roof) by the rise in the pitch you want. Divide that number by 12.
Determine the length of roof for your sloping side. Use the Pythagorean Theorem (see below).
Add on the length you want for the roof overhang (see the next section for details).
Roof Pitch Mental Math Example
For example, let’s say your chicken coop is 4 ft x 8 ft, and you want a roof with a pitch of 4:12.
You want your roof to slope down the 4 ft side of the coop. This means your roof run is 4 ft.
You know your roof length needs to be a minimum of 8 ft, but how long does your roof need to be on the sloping side (i.e., the 4’ run side)?
Step 1: Choose your roof pitch.
In this example, the roof pitch is 4:12.
Step 2: Determine the roof rise.
All you do is multiply the rise for the pitch you want—in this case 4 (this is the 4 from 4:12)—by the run, in this case 4 ft. You end up with 16 ft.
Next, divide this number (16 ft, in our case) by 12 (this is the 12 from 4:12).
So, you end up with a roof rise of ~1.33 ft.
Step 3: Determine the length of roof for your sloping side.
This means your roof needs to be 4.22 ft by 8 ft. (Remember, the coop is 4 ft by 8 ft—this is where the 8 comes from).
Step 4: Add on the length of the overhang.
Let’s say you want your roof to overhang your coop on each side by 8 inches as illustrated below.
Add 1.33 ft (16 inches) to both the length and the width of the roof.
Your roof size is 5.55 ft by 9.33 ft.
For more on why you may want an overhang and how large it should be, check out the section on overhangs below.
Online roof pitch calculator
If the mental math above is more than you want to think about, or if you want to check that your answers are correct, I recommend Omni’s Roof Pitch Calculator. This is what you’ll find if you click on link:
Step 1: Choose your roof pitch.
In this example, the roof pitch is 4:12.
Type in the pitch you want at the bottom of the calculator, where it says “Roof Pitch (x:12).” You can see that I’ve typed in that I want a pitch of “4:12.” The calculator then fills in the roof pitch (degrees) and the roof pitch (%).
Step 2: Determine the roof rise.
You know the roof run is 4 ft because your coop is 4’x8’. and you want the roof sloping down the 4’ side. Make sure you have selected the right unit of measurement in the calculator (for this example, ft). Type “4” in for “Run.”
The calculator then fills in both the rise of the roof and the length of the sloping side of the roof. In this case, the rise is 1.33 ft and the length is 4.22 ft.
Step 3: Determine the length of roof for your sloping side.
The calculator has calculated the roof length to be 4.22 ft (see the image above).
This means your roof size is 4.22 ft by 8 ft. (Remember, the coop is 4 ft by 8 ft—this is where the 8 comes from.)
Step 4: Add on the length of the overhang.
See step 4 in the mental math section above. If you want an 8 inch roof overhang on each side of the coop, your final roof size will be 5.55 feet by 9.33 feet.
Does your chicken coop roof need an overhang?
While you don’t have to have a roof overhang, also called eaves, on your chicken coop, I highly recommend it. An overhang serves a couple of purposes.
Overhangs are very handy for keeping precipitation out of the coop. A good chicken coop has ventilation high up the walls, near the roof. If your coop doesn’t have an overhang, rain and snow can get blown into the coop through the ventilation holes.
A wet coop can cause mold and other pathogens to thrive in your coop bedding. It may also cause your chickens to get wet, leading to frostbite. Even if your temperature never gets low enough to cause frostbite, wet chickens can’t insulate well, and may get too cold. At the very least, they’ll be very uncomfortable.
Eaves can also provide shelter for your chickens when they’re outside of the coop. They can get under the eaves to get out of the rain and snow. In the summer months, the eaves provide extra shade for your chickens.
I recommend you make your eaves ~8-12 inches long (and longer is even better).
Below is a photo of one of my chicken coops with eaves—you can see how much extra shade it provides.
Want to learn how to build this exact coop? Check out my chicken coop video course and plans.
Now you know how to choose your roof pitch… What about the rest of the chicken coop?
There are so many elements you need to plan for your first chicken coop. If you want to learn about them all in one easy place, check out my free video training, Chicken coops 101: design your chickens’ dream home.
I put this video presentation together to teach you exactly what you need to consider when buying or building your first chicken coop.
When I first got chickens, choosing a chicken coop was one of the most stressful things for me. I had so many little (but important) questions that I couldn’t find reliable answers for. That’s why I put this video together—to answer all those questions for you in one spot!
Check out Chicken coops 101: design your chickens’ dream home.
And if you’re interested in simply purchasing a high-quality prebuilt coop, I highly recommend Rita Marie’s Chicken Coops. After buying and testing out my own Rita Marie’s coop, I became an affiliate for this company. So, if you use this link and then buy a coop, I’ll get a small commission at no extra cost to you—a great way to support my site if you’ve found it useful.
Check out my review of my Rita Marie’s chicken coop, The BEST luxury coop you’ll ever buy: Spoil your chickens with Rita Marie’s.
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