Questions about building a coop under our deck

Right now we have a coop over by our shop, but it's a bit small and was sort of a retrofit thing so it's not all that nice. I'd like to build a bigger, better designed coop but trying to not break the bank. We do have a large area under our deck that isn't really being used for anything. The space is basically 11 feet wide by 8 1/2 feet deep and 7 1/2 feet tall. I've included a picture (don't mind the mess).

My thinking is that we could throw up some plywood to make walls and a door pretty easily. I'd like to have around 20 chickens. They have 3 1/2 acres to forage.

I guess the question is, how much ventilation is going to be necessary? What problems might there be having a coop so close to the house? (The living areas are all level with the top of the deck. The room behind what would be the coop is just a room that leads into the crawlspace and is just used for storage).

Anything I've read that seems similar at all the main concern seems to be smell. I would think that if I put in the poop shelves under the roosts and cleaned the coop often, it wouldn't be too bad. Really it should only matter in the summer when we might want to use the deck. Are solid plywood walls all around, not going to be enough for ventilation? I was thinking I could leave the 6" space above the beam that's just to the left of the window open so there would be some air flow that way. But not sure if that is really enough. Thoughts?

Edit: Our deck is weird in that it is covered and has tile on top of the wood so it stays totally dry under there as no water goes through the deck so it would be a good roof.

Cetacea33 said:

Anything I've read that seems similar at all the main concern seems to be smell. Thoughts?

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If it were me I would be more inclined to build a stand alone coop or tractor that would fit under the deck but could be moved away if things started to go sour.

I wouldn't want a coop that close to the house, but that's just me. As for ventilation, I would do around an 8" opening between the roof and walls, on two opposite sides, so that it wouldn't be drafty. Although this would be enough ventilation, it would still be very dark, so at least one window is advised. Is your deck water proof? If it's not, how are you going to put a roof on it?

If I were doing that, I think I would fence the lower section up and build them a coop that was 3 ft, or so, off the ground with a ramp going up into the floor. It would need a roof under your deck so that rain water going thru the boards of your deck wouldn't flood them.

Glad you have joined us.

If you search the forums for "coop under deck" there are a number of discussions and photo examples of what other members have considered and accomplished. You should explore those.

IMO it seems that those who have been successful have much smaller flocks with most of the area wire and not solid walls with a separate coop inside or sectioning off part of the area for the coop. Housing 20 chickens under the deck likely will be difficult to manage there. That's a lot of poop to clean daily and wheel barrow to the compost pile

The problems that the coop can bring to your home is mice, rats, snakes and other predators. Free ranging will mean leaving outside access to whatever wants to enter when it is open.

OP have already mentioned the issue that decks are designed to let water drain through and any roofing will certainly get wet and without sunshine and air circulation over the roof would bring mold and mildew to a place you won't be able to access.


If you do go ahead with the plans, do a scaled drawing of what you think would work for you, and evaluate specifically how you can access it for manure management and cleaning.

Good luck with your decisions.

Those are some good points. Sorry I forgot to mention our deck is weird in that it is covered and has tile on top of the wood so it stays totally dry under there as no water goes through the deck. The pests being drawn near the house is concerning. I hadn't really considered that. I haven't had a problem with them in the current coop. As for it being dark, I would have a couple lights in the coop anyway since I like to keep them laying well so darkness isn't a problem, but I might put a window in anyway.