DIY Chicken Coop Floor Plans for 12 to 20 Chickens

DIY chicken coop floor plans for 12 to 20 chickens: exact measurements, layout ideas, and material tips for medium to large flocks.

A flock of 12–20 chickens needs a coop that is big enough for comfort and easy to clean. This guide gives you floor plan numbers and layout ideas you can build yourself.

Square Footage for 12–20 Birds

For standard breeds, plan at least 4 sq ft per bird indoors. So 12 hens need 48 sq ft, and 20 need 80 sq ft. Giving 5–6 sq ft per bird reduces stress and keeps the coop cleaner.

Flock size	Min. coop floor (standard)	Example footprint
12 hens	48 sq ft	8×6 ft or 7×7 ft
16 hens	64 sq ft	8×8 ft
20 hens	80 sq ft	10×8 ft or 9×9 ft

Use our chicken coop calculator to adjust for bantams or large breeds. For mixed flocks, see Breed Space Needs.

Roosting and Nesting

Roost length: about 8–10 inches per standard bird. So 12 birds need ~10–12 ft of bar; 20 need ~17–20 ft. You can use several bars in a row or an L-shape. Nesting boxes: one per 3–4 hens (e.g. 3–4 boxes for 12 hens, 5 for 20). Details in How to Calculate Nesting Box Space per Chicken.

Walk-In vs Reach-In

For 12–20 birds, a walk-in coop (at least 6 ft tall) makes cleaning and egg collection much easier. Reach-in coops work for smaller flocks but become awkward at this size.

Ventilation and Materials

Large coops need plenty of ventilation to avoid ammonia and moisture. Add ridge or gable vents and windows covered with hardware cloth. Use hardware cloth, not chicken wire, on any openings to keep predators out. More in our Ventilation & Layout section.

Run Space

Plan at least 10 sq ft of run per bird (120 sq ft for 12, 200 for 20). More run space or free-range time keeps birds healthier and the coop cleaner. See Run Area Planning for fencing and layout.

Zoning and Legal Considerations

Before you start hammering nails for a coop that fits 20 chickens, check your local zoning laws and homeowner association (HOA) rules. Many urban and suburban areas have strict limits on the number of hens you can keep—often capped at 6 or 10. Some regions also have "setback" requirements, meaning your coop must be a certain distance from your neighbor's property line or your own house.

Building a large coop without checking these rules can lead to fines or being forced to rehome your birds. A quick call to your local planning department can save you a lot of heartache and money down the road.

Ventilation Strategies for Larger Flocks

With 12 to 20 birds, the amount of moisture and ammonia produced is significant. Standard windows are rarely enough. For a coop of this size, consider "cross-ventilation"—placing vents or windows on opposite walls so air can flow directly through the building.

Ridge vents (at the very peak of the roof) are also highly effective, as they allow hot, moist air to escape naturally as it rises. Aim for at least 1 square foot of permanent ventilation for every 10 square feet of floor space. In winter, you want to keep the breeze *above* the birds' heads while they roost to prevent drafts while still removing stale air.