Hoop House Calculator

A hoop house, or high tunnel, is an unheated passive solar structure: semicircular bows of bent conduit covered in greenhouse film, ventilated by manual roll-up sides. The geometry follows from treating the cross-section as a half circle whose diameter equals the house width, so peak height is half the width and each bow arc is pi times the width divided by two. A 14 foot wide house therefore stands 7 feet at the ridge and needs about 22 feet of pipe per bow. Bow count is the length divided by spacing plus one for the closing end, and covering area is arc length times house length plus end walls, with about 15 percent added for burial trenches and overlap at the baseboard. Spacing is the main structural decision. Four feet on center is the usual default, 3 feet is appropriate where snow loads are significant, and 5 to 6 feet suits only light summer shade structures. Material choice tracks span: 3/4 inch EMT conduit serves widths to roughly 14 feet, with heavier tube or bent galvanized pipe beyond that. Covering life is governed by ultraviolet degradation, so UV-stabilized greenhouse film is essential; 6 mil typically lasts 3 to 4 years against 1 to 2 years for 4 mil, while rigid polycarbonate lasts a decade or more at roughly ten times the cost per square foot. A single layer buys about 10 to 20 degrees F of frost protection and inner row cover adds several more, shifting planting and harvest windows four to eight weeks at each end of the season.

Plastic-covered growing structures date to the late 1940s, when Emery Myers Emmert at the University of Kentucky began substituting inexpensive polyethylene film for glass and published on low-cost plastic greenhouses. Film cost a small fraction of glazing and did not require heavy framing to carry its weight, which put a protected growing environment within reach of ordinary vegetable growers for the first time. Through the 1950s and 1960s film houses spread widely, and the technique underpinned the large-scale plasticultura that eventually covered much of Almeria in southern Spain. The unheated high tunnel as a season-extension tool for northern market gardeners was developed largely by university extension programs from the 1980s onward. Otho Wells at the University of New Hampshire is generally credited with adapting and promoting the movable low-cost tunnel for New England vegetable growers, and comparable work followed at Penn State, Rutgers, and other land-grant institutions. Adoption in the United States accelerated sharply after 2010, when the Natural Resources Conservation Service added seasonal high tunnels to its Environmental Quality Incentives Program as a recognized conservation practice and began cost-sharing them, funding tens of thousands of structures on small farms. The bent-conduit, roll-up-side design that most hoop house plans still follow comes out of that extension and cost-share tradition rather than from commercial greenhouse engineering.