Free Guide · Fixing a Smelly Chicken Run
A smelly coop is not a cleaning problem. It is a balance problem, and that is very good news.
Why does my chicken coop smell? Because the floor has gone anaerobic, and the ammonia has nowhere to go. Stop treating that floor as a floor and start treating it as a giant compost bin: a base layer of compressed pine pellets, straw on top, and the balance between wet and dry kept right. The worms and microbes move in on their own and do the rest.
This is the question I get more than any other about Chicken City, my integrated chicken coop, veggie garden, fruit orchard and compost system all under one roof. Does it smell?
It does not. I did worry that I had simply got used to it over the years, so I asked a few friends over to give it a proper whiff, and the jury came back unanimous. It smells sweet and earthy, like a compost bin that is going well. That is with twenty chickens living here at the time I filmed it.
None of that is luck. There are a few things I do and one way of thinking you need to adopt, and it is genuinely simple once you know how.
Watch
Laying the floor, start to finish
I dig the courtyard back to bare earth, put the pellets and straw down, and show you what a well balanced run floor actually looks like up close.
Stop thinking of it as a floor
This is the whole thing, and everything else follows from it. The floor of your chicken run is not a floor. It is a giant compost bin that happens to have chickens standing on it.
If you already understand composting, you already understand this. A compost bin that is going well smells sweet and earthy. One that is out of balance stinks. Your run floor behaves exactly the same way, for exactly the same reasons, and it responds to exactly the same fix.
The chicken manure is the wet, or the nitrogen. What you add is the dry, or the carbon. Keep those two in balance and you are composting in place, right there on the ground. Get it wrong and you are running an anaerobic pile in your back garden, which is precisely what a bad coop smells like.
This is usually called the deep litter method, and if you want to read more that is the term to search. I do not love it. I prefer the giant compost bin idea, because most gardeners already know how composting works, and learning a new piece of jargon just puts distance between you and something you already understand. It is the same thing either way.
The rule, in one line
Too wet and smelly, add carbon. Too dry and dusty, add moisture. That is the entire maintenance routine.
What is actually making the smell
When people say a coop smells, what they usually mean is ammonia. That is the white part of chicken droppings, effectively the urine, and if it builds up it is sharp and unmistakable.
A living floor deals with it. Worms and microbes churn through the manure and through the ammonia with it. The worms do something else just as important: they tunnel, and those tunnels are air channels. A floor full of air channels stays aerobic. A floor that has been compacted flat has no air in it at all, and an anaerobic floor will always smell, no matter how often you clean it.
So the goal is not a clean floor. The goal is a living one.
Also on the channel
Why the floor can be bare earth
None of this works if you have wire or concrete underfoot. The reason I can compost straight onto the ground is what we did around the perimeter instead, which is all in the build video.
You do not need to add worms
People ask me this a lot. Did I seed the floor with worms? Absolutely not. Build it and they will come.
Create an environment that suits worms and microbes and they will find you, exactly the way they find a compost bin you have never inoculated with anything. I have never added worms to my compost bays either. You make the conditions, they turn up and do the work.
The two materials I use
Compressed pine pellets, the base layer
These are the single best thing I have found in all my years of chicken keeping. I did not use them at the start, and the day I did, everything changed.
They are usually sold as horse bedding, occasionally as cat litter. Read the bag. You want pure compressed pine and nothing else. Not the chemical cat litters, not the clay ball ones. The pellets go down bone dry and hugely compacted, and when rain or droppings hit them they expand and absorb everything. They do the heavy lifting from the bottom of the floor upwards.
My chickens have a good look at them the first time they go down and then ignore them completely. They scratch through, work out there is nothing in it for them, and move on.
Straw, the top layer
Straw is the fun one. It absorbs well, it adds carbon, it is cheap, and the chickens adore scratching through it, so it is enrichment as well as bedding. It does not soak up anything like as much as the pellets, which is why it goes on top rather than instead.
How to lay it
Start on bare earth on a dry day. My run floor has no wire and no concrete under it, because the security is handled around the perimeter instead, so there is nothing between the litter and the soil. Let it dry out first if you can, because you are trying to establish the dry side of the balance.
Pellets first, always. They are the base and the super absorber. I use about two bags across the courtyard.
Straw on top. One bale does the whole courtyard. Cut it open, pull the biscuits apart roughly and throw them around.
Do not spread either one carefully. I throw both down in piles and let the chickens distribute it, which they start doing within minutes and clearly enjoy. You could rake it out properly. Save yourself the time. The whole job takes me about five minutes.
Keeping the balance through the year
Winter is when the pellets earn their keep. Where I am there is a lot of rain, and the run gets genuinely wet. As soon as it starts going muddy and sloppy, more pellets go down and the deep litter builds up.
Summer is the opposite problem. Dust is the other thing people complain about in a run, and the fix is moisture. Because I have plants growing in the run that need watering anyway, the courtyard floor gets watered at the same time. One job, two results, which is how most of Chicken City is designed.
Top up rather than dumping it all in at once. What I put down on day one is a good start but not yet a real deep litter system. Every couple of weeks I add more carbon, and it builds up over the season. By the end of one it might be around 15 centimetres deep, sometimes more. You are genuinely raising the floor level. I find layering as you go works better than going in hard at the start.
The twice a year dig out
Twice a year I dig the whole floor up, take the entire deep litter system out and start again. This is the part I do not enjoy. It is heavy, it is all done by hand into buckets, and I put it off.
How do I know when? When the floor is so wet and muddy and gross that starting again is easier than fixing it. In practice that lands twice in the cooler months, roughly end of autumn or start of winter, and then again around the end of winter into spring. Through summer the pellet and straw routine holds it comfortably.
And here is the payoff that makes it worth the back. What comes out is extraordinary garden food. Because the courtyard sits in the middle with the fruit, veggie and berry rooms coming off it, I barrow those buckets straight into the beds around it and top dress like I would with any compost. It is a huge injection of nutrients exactly where it is needed, and it is the reason I do not buy fertiliser. Everything my garden gets comes from the animals here, mostly the chickens, with some from the horses and goats.
All of which eventually turns into breakfast, which is the part nobody warns you about. There is no bacon in my No-Bacon Bacon Salt, and no pig either, which feels like the right way round in a house where the animals are pets rather than dinner. It is smoky and savoury and it goes onto a fried egg like it was made for one.
Alyce's Favourite
All the flavour, none of the pig (because we love pigs!)
Alyce's No-Bacon Bacon Salt
Smoky, salty and seriously savoury. Made for a fried egg.
Shop the No-Bacon Bacon SaltWhat goes wrong
It still smells after all that
Add more carbon first and give it time. If it is genuinely dire, garden lime is the one to have up your sleeve. Garden or agricultural lime, never builder's lime. It goes down on the bare earth at the very start of the layering, before the pellets, not sprinkled over the top later. I have never actually needed it, but it is there.
It is the chicken house that smells, not the run
Different problem. Put pine pellets down as the bedding in the house itself first, because they will absorb almost anything. If it still smells after that, the issue is ventilation. Chicken houses need a lot of it, and the ammonia produced as droppings break down has to be able to escape. You want upper level airflow moving 24 hours a day, in winter just as much as in summer.
And take this one seriously: if you can smell ammonia in the house, it is already a problem for your chickens' health, not just for your nose.
The floor has gone hard and flat
Compaction means no air, and no air means it will smell whatever you do. More carbon, and let the chickens scratch it in. They are the ones who keep it aerated.
One particular chicken smells
That is a different signal entirely and worth acting on. A healthy chicken does not smell. Have a look at her face for canker sores, listen to her breathing, because a respiratory infection can smell very bad, and check her vent is clean and working as it should. If something seems wrong, see a vet rather than guessing.
Smell is information, so use it
This is the habit I would most like you to take from all of this. A bad smell in a garden almost always means something is wrong, and it is telling you before anything else does.
If the compost stinks, the balance is off. If the run stinks, it is the balance or the ventilation. If a chicken stinks, she is unwell. I worked out that Remy, our big goat, had a respiratory infection because the smell of his breath had changed. Nothing else had told me yet.
Your nose is a diagnostic tool you are already carrying around. Use it while you are out there.
Frequently asked questions
Why does my chicken coop smell like ammonia?
Ammonia builds up when droppings break down without enough carbon and enough air. Add a dry carbon layer, keep the floor from compacting, and in an enclosed chicken house check the ventilation, because the gas needs somewhere to go.
Are pine pellets safe for chickens?
Plain compressed pine pellets are what I use, and mine investigate them once and then leave them alone. Buy pure compressed pine, not chemically treated cat litter and not clay based products.
How deep should deep litter be?
It builds rather than starts deep. Mine gets to roughly 15 centimetres by the end of a season, sometimes more, by topping up with carbon every couple of weeks rather than laying it all at once.
How often do you clean out a deep litter chicken run?
Twice a year here, both times in the cooler months, and the trigger is the floor getting too wet and muddy rather than a date in the calendar.
Do I need to add worms to the run floor?
No. Get the conditions right and they arrive on their own, the same way they colonise a compost bin you never seeded.
Can I use the old bedding in the garden?
That is the whole point of it. What comes out of the run twice a year goes straight onto my garden beds as a top dressing, and it is why I do not buy fertiliser.
Building your own version of this?
I have been refining Chicken City for over ten years and I share what works, what failed, and what I would do differently. Come along for the rest of it.
More from Chicken City
Why you should be composting covers the same principles in an actual compost bin, which is where most people meet them first.
Simple tricks to protect plants from chickens is how you get plants growing in the run that make the watering do double duty.
How to stop chickens destroying your berry plants is the berry version of the same idea.
Chicken City, the details has the structure, the design thinking and rough plans.
Watch next
The full tour, every room
If you want to see where all that composted floor ends up, this walks through the whole system: the courtyard, the berry room, the veggie rooms and the fruit room.
