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Why Does My Chicken Coop Smell? How to Keep Your Chicken Coop From Smelling Bad

Many chicken keepers ask a question that concerns them greatly: why their chicken coop smells so bad? The bad smell is usually an ammonia smell. It’s essential to respond quickly if you smell ammonia because inhaling ammonia is dangerous to your chickens’ health.

The smell in a chicken coop is often caused by ammonia. This is because chickens produce a lot of waste, and when it’s not cleaned out regularly, the ammonia builds up and causes the smell. There are a few things you can do to help reduce the smell in your chicken coop, including adding a layer of sand or straw to the floor, providing more ventilation, and cleaning out the coop regularly.

You need to understand where the ammonia smell is coming from, how it’s created, and the environmental elements within the coop that enable and foster its production. Armed with that knowledge, you can then take the necessary actions to ensure that your coop is ammonia-free, fresh-smelling, and healthy. Read on to learn how to stop your chicken coop from smelling bad.

Why Does My Chicken Coop Smell Like Ammonia?

Ammonia is a colorless gas with a sharp, distinctive odor. It’s produced when nitrogen-containing compounds are broken down. Chicken feces and urine are mixed together (chicken poop) contains high levels of nitrogen, so it’s not surprising that chicken coops often smell like ammonia. 

Unused nitrogen is excreted as uric acid (80%), ammonia (10%), and urea (5%). When the ammonia is exposed to moisture, it reacts and forms a basic, corrosive mixture called ammonium which Can cause health issues in your flock including respiratory issues, decreased egg production and bacterial growth.

While it may not kill your birds, ammonia can cause eye and respiratory diseases, lower their disease resistance, and decrease the growth rate and body weight of young birds. Ammonia negatively impacts immune organ development, damaging the chickens’ immune system and ability to absorb nutrients. Ammonia is one of the main culprits causing air pollution in chicken coops.

How To Remove The Bad Smell And Make Your Coop Smell Better

Well, the most obvious answer is chicken excrement and it’s what ultimately creates all the rest of the problems. Unfortunately, you can’t stop your chickens from going to the toilet but you can control the matter considerably!

The smell that comes from the chicken’s waste is ammonia which is a by-product of chicken feces and there is no way to control that. However, it is heavily impacted by the levels of moisture in the coop, if you lock out moisture you prevent the smell.

How to Prevent Ammonia Smells and bad odors in Chicken Coops 

Many elements contribute to the intensity of ammonia inside a coop. Overcrowding, poor waste management, and humidity can all play a role. Since the toxic process occurs when the ammonia is exposed to moisture, you need to keep the moisture levels in your coop to a minimum. It’s essential to keep the whole coop dry, including your coop bedding.

There are several ways to do this. You must ensure adequate ventilation, prevent water from entering the coop, only house the recommended number of chickens, and clean the coop thoroughly. You may want to try the “deep litter method” method.

1. Provide Adequate Ventilation

To prevent a smelly coop you should always make sure to have good ventilation. Good ventilation will help to remove ammonia odors from the air and keep your chickens healthy. Ventilation is an essential element in controlling ammonia concentration. Good ventilation will eliminate excess moisture from the air and bedding. The toxic gases will be removed and replaced by fresh air. 

Chicken coop ventilation consists of points where air can enter the coop and exit after circulation. This differs from drafts which are caused by random holes that cannot be controlled and will let in too much cold air. A coop should be well-ventilated but not drafty.

When you plan the ventilation of your coop, consider its size because that will determine how much ventilation is required. It’s recommended that for every ten sq. ft. of floor space you have, you need one sq. ft. of ventilation.

More ventilation will be required if you live in hotter than average areas. In a hot climate you can install a screen on one side of the coop for ventilation. In warmer months, it’s better to have the ventilation lower (at roosting and nesting height) to allow a cool breeze into the coop. In more inclement climates it may be better to have a few windows or a screen door that can be open for the summer months but can be closed off in winter.

In cold weather, aeration is equally important to prevent a build-up of humidity. High humidity levels within the coop can create too much moisture and cause respiratory issues in your flock. During the winter months, the vents should ideally be at a height above the chickens’ heads so that the birds are not subject to a direct stream of frigid air.

having ventilation and doors that can open to provide good ventilation

2. Prevent Moisture Build-Up In The Coop

  • Is the bedding your chickens are laying and walking on trapping moisture? Wet litter is a great way to cause a stinky coop. Never use hay or straw as your choice of bedding as they retain moisture. Instead, use pine shavings and turn the bedding with a pitchfork.
  • Is there a leak in the coop allowing rainwater to enter, or is it weatherproof? You can use straw however in nesting boxes.
  • Are your chickens spilling and messing with water when they drink from a trough or other water bowls? This could be making their bedding wet. A way to prevent this is to use chicken nipples, a handy little device that when pecked at releases a few drops of water to the chickens. The chicken nipples can screw into buckets or other water holders.
  • For outdoor areas of the coop, ensure good drainage. A gravel base with thick sand on top will let rainwater seep through it.

3. Drainage outside

When we first got chickens, we put them on grass as many farmers said they like being on there. This is true to an extent but, if you’re considering doing the same, you may want to read our article on how to Do chickens need to be on grass. 

But put shortly, the answer is no and although our hens liked the grass it wasn’t necessary and caused a lot of issues one of them being the smell.

This is a common cause for an odorous coop as after a few days you’ll find the grass turned into muck from the chickens trampling and pecking at the grass, combined with some rain caused the outside area of the coop to be a mucky, smelly pile of mud as waste, there was no drainage so everything collected up until the smell was unbearable.

An easy way to solve this problem is to have the outdoor section of your coop coated with an inch or two thick layer or bark chipping or gravel, not to be confused with wood shavings that go inside the coop. The bark chippings are a good absorber and take some of the kick out of the smell however to further protect your coop, we’d recommend installing a roof so no moisture can enter the coop.

4. Don’t Over-crowd Your Coop

It is recommended that you provide 3 square feet ( 1/3 sq. m) per chicken in your coop. The minimum area for one hen in a chicken run is 10-12 sq. feet (1 sq. m) per hen. This helps to prevent excessive moisture in the coop. I have a whole article on the space requirements for chickens here.

5. Clean and Deep-Clean Your Coop Thoroughly

One of the easiest ways to prevent an ammonia smell in your hen house is to remove the sources of nitrogen and keep a clean coop. This means cleaning out the coop on a regular basis and disposing of the manure and bedding material in a way that prevents it from decomposing and releasing ammonia fumes into the air. 

  • Scoop out droppings every day and deep clean thoroughly as needed. It’s best not to use chemicals when you do this. A homemade mix of water and vinegar will work well. The waterer and feeders must also be cleaned. If you have a concrete floor in your coop, this will have to be mopped down. Sprinkle diatomaceous earth or agricultural lime on the floor of the coop to help absorb any bad smells
  • We usually change the bedding in the coop every week and let the coop air out by opening the doors and allowing full air circulation which also helps reduce and odors. For our full maintenance schedule check out my article here.
  • Use the “deep bedding” or “deep litter” method to prevent moisture build-up (see below). With this method, it will only be necessary to clean the litter once or twice a year.
pine shaving are a good litter to use in the coop to help stop bad smells

Using The Deep Litter Method or Deep-Bedding Method

This is a way of managing the chicken manure within the coop. The chickens’ feces falling on the ground are mixed with a deep layer of wood shavings or wood chips and constantly aerated to create a compost pile.

When done correctly, the deep-litter method has many benefits. It means you spend much less time cleaning the coop, and it provides you with good garden compost. If managed successfully, your coop won’t have a bad smell, and your chickens will remain healthy.

Firstly, a layer of pine shavings about 6 inches (15 cms.) deep needs to be laid down. This is the “browns” or carbon-rich category of potential compost. The chicken poop falling into this layer is high in nitrogen (the “greens” category). You then add another layer of litter. (Never use cedar shavings as these can be toxic and deadly for chickens.)

A critical activity to maintain is aerating the litter because the oxygen keeps the decomposition process going. Your chickens will contribute to this process when they scratch in the litter. You could encourage this behavior by scattering some corn or feed on the coop floor so your chickens peck around. If the chickens miss a spot, use a light rake or pitchfork to aerate that section of the litter.

Then you build up the litter bed with fresh bedding to about 12 inches (30 cms). You need to turn the bedding frequently with a shovel or pitchfork, so the chicken droppings fall to the bottom. Dry grass clipping, leaves, and pine needles in small quantities can also be added as long as they don’t contain moisture.

This method will not work if your coop is overcrowded. There should be one chicken for every four feet (1, 2 m).

The compost ratio in this method is 30:1. In other words, 30 parts of carbon-based litter to one part of chicken poop. If this ratio is not maintained, high ammonia levels will form. Turning the litter adds oxygen, reducing the chance of ammonia forming.

 You need to correct the compost balance if you notice a foul smell. You must aerate the pile or build up the litter if the smell persists. If that also doesn’t work, the coop will have to be cleaned, and you’ll have to start over.

Below is a helpful video showing a Scandinavian farmer explaining how to use this method.


Preventing a bad smell in your coop is an important priority, not just because it’s so unpleasant but also because it’s key to keeping your chickens healthy. An ammonia smell in your chicken coop is a sign that there are too many sources of nitrogen present.

To prevent an ammonia smell, clean out the coop regularly, dispose of manure and bedding material properly, and make sure that your coop has good ventilation. Taking these simple steps will help to keep your chickens healthy and happy.

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