10 square feet is a three-hen coop, and three means three
This is the smallest design in the line and the capacity is not padded. Two hens is comfortable. Three is the ceiling.
At 3 birds each hen gets 3.3 square feet of coop floor. That sits inside the 3-4 square feet per bird Oregon State, Virginia Tech and eXtension publish, but only because there’s an attached run. A bird with no outdoor access needs 8-10 square feet indoors — the requirement goes up when the run goes away, which catches people out.
The roosts hold up better than the floor does. 30 inches of bar across 3 birds is 10 inches each, the generous end of the 6-to-10-inch range Penn State, Oregon State and Maryland Extension publish. Nobody is fighting for a spot on the bar here.
The run is the pinch point. 16 square feet across three hens is 5.3 square feet a bird, under the 8-10 square feet extension services recommend for a permanent run. The shaded ground under the 18-inch raised floor adds roughly the same again by our own count. Even so, these birds want time out of the pen most days.
What it costs against the alternatives
| Design | Coop | Run | Hens | Roost | Build time | Materials |
|---|---|---|---|---|---|---|
| 4x8 A-frame tractor | 10 sq ft | 16 sq ft | 2–3 | — | 14–20 hrs | $675–$875 |
| 4x4 starter (this one) | 10 sq ft | 16 sq ft | 2–3 | 30” | 10–14 hrs | $1,650–$2,150 |
| 4x6 coop | 16 sq ft | 24 sq ft | 3–4 | 40” | 18–26 hrs | $1,900–$2,450 |
Two honest things fall out of that table.
First, this is the cheapest coop in the line and it is not a cheap coop. $1,650 for 10 square feet of bird floor is real money, and the A-frame tractor sleeps the same two or three hens for $675. You’re paying the difference for a permanent raised structure on posts and pier blocks, with a buried apron.
Second, the step up to the 4x6 is the best value on this page. $250 to $300 buys six more square feet of coop, eight more of run, ten more inches of roost and a second window. Building too small is the most repeated regret in coop plan reviews. This is the cheapest possible insurance against it.
Tractor or fixed coop — decide this before you buy lumber
The 4x8 A-frame and this design house the same flock. They solve different problems, and price is the smallest difference between them.
A tractor moves. You drag it to fresh grass every few days, the birds fertilise as they go, and no patch gets scratched to bare dirt. The trade is that a movable frame can’t carry a buried apron, so its predator protection depends on the ground it happens to be sitting on tonight.
This design doesn’t move, and that’s the point. Posts, pier blocks and 12 inches of buried hardware cloth around the whole perimeter give you exclusion a tractor can’t. Pick the tractor for grass, pick this for security. The tractor plans guide walks through that trade in detail.
36-inch studs mean you’re on your knees for every cleanout
Access is reach-in. Stud height is 36 inches and the door is 30 by 30. There’s no standing up inside and no walking in with a rake.
That’s the real cost of the footprint, and it’s worth sitting with before you commit. At 10 square feet it’s a five-minute job on your knees, which most people find fine. The same posture over 30 or 40 square feet is what makes owners of larger reach-in coops describe cleaning them in language we won’t print.
Two things make it easier. Keep the droppings board removable so most of the mess comes out in one piece. And site the coop so the 30-inch door faces the way you approach it, not the fence — you can’t walk around the back of this one.
42 inches of span, four joists, and nothing to worry about
The floor spans 42 inches between rims on four 2x6 joists at 16 inches on center, with no girder. That’s less than half of what the table allows.
AWC DCA6-2015 Table 2 rates a 2x6 at 16 inches on center at 8 feet 4 inches in the weakest tabulated species, wet service. This design uses 3 feet 6 inches of that. The floor is not what limits this coop, and you will never see it deflect.
That margin is why this is the Beginner build. There’s no beam to size, no mid-span post to place and no rafter tie geometry to get right. It’s the design to learn the joints on before you attempt an 8x10 walk-in.
1.5 square feet of vent on a very small box
This design carries 1.5 square feet of permanent vent for 10 square feet of floor. We size vents at 1 square foot per 10 square feet of floor. That ratio is our own default — no extension service publishes it, whatever you’ve read.
Small volumes swing faster than big ones, so the ratio matters more here, not less. What the research actually measures is the outcome. Kang and colleagues, publishing in Frontiers in Veterinary Science in 2020, found that a fast heat spike kills laying hens far more readily than the same peak reached gradually. A small, tight box heats fast.
The single window is not your ventilation. A closed window vents nothing, so the 1.5 square feet is permanent opening above roost height. Don’t shut it down for winter either — frostbite is a moisture problem, not a cold one, which University of Minnesota Extension states directly. The ventilation guide has the rest.
Small coop, same predators
Nothing about three hens makes a raccoon less interested. The material list calls for 52 feet of quarter-inch, 19-gauge hardware cloth, and every foot of it is load-bearing for the flock’s survival.
Quarter-inch, not half-inch. Half-inch stops raccoons and a least weasel goes through anything a quarter-inch or larger — University of Kentucky Extension documents that in ID-245. The same publication explains the mechanism people miss: a predator never has to get inside. The gap only has to admit a paw.
Bury 12 inches of apron down and out around the run. Kentucky, Maryland and Florida extension services confirm that depth independently. On a perimeter this small it’s an afternoon, not a day. Full detail in the predator-proofing guide.
What this design deliberately does not do
It doesn’t grow. There’s no expansion joint, no partition to remove and no way to add run length without rebuilding the end wall. Three hens is where it starts and where it finishes, so buy the 4x6 if you suspect the flock will.
It isn’t insulated, and it doesn’t need to be. Insulation’s real job is keeping interior surfaces above the dew point so moisture doesn’t condense on the walls, which University of Kentucky sets out plainly. Insulation without ventilation makes moisture worse, not better.
The two nest boxes across a 30-1/4 inch bank are more than three hens require. One box per four to five hens is the figure UC Davis, Certified Humane and RSPCA agree on. Two are here because hens queue for the favourite box, and it’s always occupied at the wrong moment. The nesting box guide explains the rest.