Calculate materials needed for greenhouse hoop house construction
Updated: 4/29/2026
feet
feet
feet
feet on center
Hoop Length
17.2
feet per hoop
Number of Hoops
6
pieces needed
Plastic Sheeting Size
21' × 38'
with overlap allowance
A hoop house (also called a high tunnel or poly tunnel) is a low-cost, portable greenhouse structure made from curved metal hoops covered with plastic sheeting. The arched design provides structural strength while maximizing interior volume, making it ideal for extending growing seasons in cold climates, protecting plants from frost, and creating a controlled microclimate for year-round gardening.
Hoop houses are significantly cheaper than traditional frame greenhouses while providing similar climate control benefits. They're popular with commercial growers for extending harvest seasons and home gardeners for starting seedlings and protecting tender plants. Typical hoop houses last 4-10 years depending on climate, UV exposure, and maintenance.
Circular Geometry: This calculator assumes the hoop forms a perfect circular arc based on width and height. Real hoop houses are often built with semi-elliptical or pre-bent tubing that may vary from ideal circular geometry. Results are closest for custom-bent hoops.
Plastic Margin (+4 ft): The plastic width and length include a fixed +4 ft allowance for overlap and ground securing. Your actual needs may vary based on: ground slope, anchor method, desired overlap, and end wall construction style. Measure your specific site and add appropriate margins.
No Load Analysis: This tool calculates dimensions only. It does not account for snow loads, wind ratings, or structural adequacy. Verify hoop sizing with structural requirements for your region.
Width: typically 9-20 ft. Height: usually 6-8 ft. Length: 20-100+ ft depending on space. Hoop spacing: typically 4-6 ft on center.
Hoop forms a curved arch. This calculator uses circular segment calculations to determine the exact hoop length needed for your specified width and height.
Based on your spacing (typically 4-6 ft), the calculator determines how many hoops you need spaced along the length.
Plastic width must cover the hoop length plus overlap for securing. Length must cover the building length plus end walls and ground overlap.
Scenario: Standard 12 ft wide × 7 ft high × 40 ft long hoop house with 4 ft hoop spacing
Inputs: Width=12', Height=7', Length=40', Spacing=4'
Galvanized steel EMT conduit (1-1/2" or 2") is most common. PVC is lighter but less durable. Some use rebar secured in concrete footings. Galvanized steel lasts 10-15+ years.
4-6 mil UV-stabilized greenhouse plastic lasts 3-5 years. 6-mil lasts 4-7 years. Thicker (8 mil) lasts longer but costs more. Harsh climates reduce lifespan.
Ground cover (landscape fabric at base), binder twine or rope over plastic, or specialized clips. Bury edge 12-18" underground for wind resistance. Proper tension prevents flapping and damage.
Critical! Install roll-up sides (manual or automatic openers at 70°F) or end wall vents. Overheating kills plants even in winter. Passive ventilation via gaps works in some climates.
More hoops (3-4 ft spacing) provide better snow load support and wind resistance but cost more material. Standard 4-6 ft spacing handles typical snow loads in moderate climates.
Yes, that's a key advantage! Disassemble hoops, fold plastic, and relocate. Moderate-sized structures (12×20) are reasonably portable. Very large ones (20×100) are impractical to move.
Hoop houses are cheaper and more temporary. Greenhouses are rigid-frame structures lasting 20+ years. Hoop houses are better for: seasonal extension, low cost, mobility. Greenhouses for: long-term, high-tech systems.
Basic systems: thermometers and manual venting. Advanced: automatic vent openers, shade cloth, heaters. Drip irrigation and humidity sensors improve efficiency. Start simple and upgrade if needed.
This calculator provides materials estimates only. It does not account for snow load zones, wind ratings, or local building codes. Plastic lifespans vary by UV degradation, climate, and installation quality (typically 3-7 years). Large structures require structural engineering. Consult local building officials and structural engineers before construction, especially in high-wind or high-snow regions.