Short answer: a fresh-air coop is a deep, tight-walled house with part of its south front left permanently open, covered only by wire mesh. Because the house is deep and the roosts sit at the back, wind and snow don't reach the birds, while damp air leaves through the open front all night. Dr. Prince T. Woods published the classic design in 1912. Its owners reported dry houses and healthy flocks from Massachusetts to Quebec and British Columbia.
Where the idea came from
By the early 1900s many poultry keepers had sealed their hens into tight, closed houses for winter. Woods, a physician and poultry writer, argued that these houses were the problem: "A closed house that has no heat is usually too warm on a sunny day and too cold and chill on cloudy days or at night." Damp, stale air, not cold, was what made flocks sick.
He built an experimental open-front house at Topsfield, Massachusetts, in 1908, then published the plans in Open-Air Poultry Houses for All Climates (1912). The book is now in the public domain. Its scanned pages are free on the Internet Archive, and modern reprints are sold as Fresh-Air Poultry Houses.
How it works
- Tight on three sides. Roof, rear and side walls are built weathertight. The only opening is in the south front.
- Open all year. Woods wrote that the opening "stays open night and day the year 'round. There are no curtains of any kind." Its only protection is the overhang of the eaves and a screen of ¼-inch (6 mm) galvanized wire netting.
- Deep in proportion to the opening. His rule was that the house must be "sufficiently deep in proportion to the expanse of open front." Then storms won't drive in to any troublesome extent. Wind and rain spend themselves in the first few feet.
- Roosts well back. Perches go at the rear, far from the opening, with "plenty of head room about the roosts."
- Light where it's needed. His larger houses carry a raised "monitor" roof with windows that bring sun to the back of the house. The windows stay shut in winter and open in summer.
Does it really stay dry?
Woods tested it in a storm. In the fall of 1911 a gale drove rain "on a slant that was but little more than the horizontal" into the open front of his Plymouth County house. Inside, he reported, the wind "could not be felt at all" four feet back from the front. Less than one yard of floor behind the wire got wet. The same design was used through four-foot snows in Quebec and in British Columbia, and in 1910 a Connecticut farm built one 400 feet long.
The physics matches modern advice. Hens breathe out a great deal of moisture, and moisture plus cold is what causes frostbite. An open front exchanges that air constantly without a fan, and the depth keeps the exchange from becoming a draft across the roost.
Woods' house sizes
- 8 × 14 ft (2.4 × 4.3 m): small colony house for 5–25 birds
- 10 × 16 ft (3.0 × 4.9 m): 30–40 birds
- 10 × 18 ft (3.0 × 5.5 m): 40–60 birds
- 20 × 20 ft (6.1 × 6.1 m): his main colony house, "comfortable quarters for 100 layers," about 4 sq ft (0.37 m²) per bird
Notice the proportions. Every one is far deeper than a typical modern backyard coop of the same floor area, and that depth is what makes the open front safe.
Building one today
- Face it south (north in the southern hemisphere), with the back and sides to the prevailing winter wind.
- Use welded hardware cloth, not chicken wire, over the opening and fasten it to framing on all four edges. Woods' mesh kept sparrows out; today's raccoons need something stronger.
- Don't shrink the depth. If you can't build deep, make the opening smaller rather than the house shallower.
- Keep the eaves. The roof overhang is part of the weather protection.
- Resist the curtain. Woods was blunt that cloth or burlap over the opening defeats the purpose. It collects dust and stops the airflow the house depends on.
If you'd rather start from a tested drawing, the 1974 Small Poultry House is a closed, insulated 8 × 12 ft laying house for 25–40 hens. It's the opposite approach, with high vents doing the work of the open front. For summer, the Summer Range Poultry Shelter is a 10 × 10 ft netting-sided range shelter on skids for growing birds. Our guides on coop size and winterizing a closed coop cover the rest.
Frequently asked
Won't the chickens get frostbite with an open front?
Frostbite comes mostly from damp air settling on combs and wattles. A deep open-front house stays drier than a closed one. Woods' book reports that even large-combed Minorcas and Leghorns did better in open-front houses than in closed ones. Roosts must sit well back from the opening, out of any draft.
Can I convert my existing coop?
Sometimes. If the coop is deep compared with its front wall, you can open part of the south side and cover it with hardware cloth. In a small, shallow coop an open front will let weather reach the roost, so stick to high vents instead.
Is an open-front coop the same as a hoop coop?
No. A hoop coop is a covered frame that's often open at the ends. The fresh-air house is a framed, roofed building with tight walls and a single protected opening sized against the house's depth.
Quotations and figures from Prince T. Woods, M.D., Open-Air Poultry Houses for All Climates (American Poultry Journal Publishing Co., 1912), public domain. Photo: Woods' experimental house, Topsfield, Mass., 1908, from the same book.