homestead.fyi / TUNNEL-20X48

20x48 High Tunnel

A 20 x 48 ft high tunnel, 101 in at the crown, of 13 galvanized pipe bows on driven ground posts, five purlins, 2x6 baseboards, wooden end frames and a film cover.

Draft plan, generated from the model. Not yet build-tested.
20 x 48 ftFootprint
960 sq ftFloor
101 inCrown
13Bows
60 to 100 hrBuild time
~$3,702.61Materials, part estimate

Drawings All dimensions in inches

3D viewfinished
3D view
3D view, framingsiding and roof removed
3D view, framing
Front elevation
Front elevation 244 1/4 in 127 1/4 in
Right elevation
Right elevation 588 in 127 1/4 in
Plan viewfrom above
Plan view 244 1/4 in 588 in

Cut list: lumber Long-point lengths; angles noted

QtyStockLengthPartCut
22x484Door post fronton edge, wired to the end bow
22x484Door post backon edge, wired to the end bow
12x443Door header fronton edge
12x443Door header backon edge
52x6 GC115 1/4Baseboard lefton edge, bolted to the posts, film clamped on top
52x6 GC115 1/4Baseboard righton edge, bolted to the posts, film clamped on top

Lumber cutting diagram Lengths chosen for the lowest cost; 1/8 in kerf, 1/2 in end trim

2x4 x 8 ft
Door header front 43Door header back 43
2x4 x 8 ft
Door post front 1 84
2x4 x 8 ft
Door post front 2 84
2x4 x 8 ft
Door post back 1 84
2x4 x 8 ft
Door post back 2 84
2x6 GC x 10 ft
Baseboard left 3 115 1/4
2x6 GC x 10 ft
Baseboard right 3 115 1/4
2x6 GC x 10 ft
Baseboard left 1 115 1/4
2x6 GC x 10 ft
Baseboard left 2 115 1/4
2x6 GC x 10 ft
Baseboard right 1 115 1/4
2x6 GC x 10 ft
Baseboard right 2 115 1/4
2x6 GC x 10 ft
Baseboard left 4 115 1/4
2x6 GC x 10 ft
Baseboard left 5 115 1/4
2x6 GC x 10 ft
Baseboard right 4 115 1/4
2x6 GC x 10 ft
Baseboard right 5 115 1/4

Shopping list $3,491.61 checked / $211.00 estimated

ItemStoreQtyEachLineNote
2x4x8 stud, SPFHome Depot5$4.15$20.75see lumber cutting diagram
2x6x10 ground-contact pressure-treatedHome Depot10$12.98$129.80see lumber cutting diagram
1-5/8 in galvanized chain-link top rail, 21 ftMenards67$39.99$2,679.33bows (two 21 ft pipes each, bent and sleeved), ground posts (cut from 21 ft pipe) and five 48 ft purlin runs
Galvanized purlin clamps, 1-5/8 in, 10 packGreenhouse supplier7$25.00$175.00purlin clamps, 10 pack
6 mil greenhouse film, 4 year, 32 ft x 100 ftEndless Summer Garden & Hydro1$275.00$275.0032 x 100 ft film
Wiggle wire and channel, about 100 ft (steel)Farm Plastic Supply3$110.00$330.00wiggle wire and channel
Carriage bolts, nuts and washers, 12 packHome Depot3$12.00$36.00
Exterior wood screws #9 x 2.5 in, 5 lb boxHome Depot1$29.97$29.97
Galvanized 6 in strap hinge, each (5-pack $32.99)Home Depot2$6.60$13.20doors
Galvanized staple safety hasp, 3-1/2 inHome Depot2$6.78$13.56doors
Total before tax~$3,702.61
Filled dot: price read from a store listing on Oct 20, 2026. Hollow dot: estimate. Prices come from the master price list, so they change when it changes.

Build steps

  1. Pick a level, well-drained site with full sun and 20 x 52 ft free. Lay out the corners with string and check both diagonals for square.
  2. Drive 26 ground posts, 24 in deep, 4 ft apart along each side, 20 ft apart across, with a string line to keep them straight. Check each pair with a level.
  3. Slip the bows over the ground posts and bolt them on. Each bow is a 29 ft length of 1-5/8 in galvanized pipe, bent to a gothic arch 101 in tall: buy it pre-bent, or bend it with a pipe bender.
  4. Clamp five 1-5/8 in purlins along the length, one at the ridge and two on each side, with a clamp at each bow.
  5. Bolt the 2x6 baseboards to the ground posts along each side, on edge, 5 in off the ground.
  6. Frame the two end walls with 2x4 posts and a header, wired to the end bows, with a 3 x 7 ft door in each.
  7. Pull the 32 ft wide film over the bows in calm weather with at least four people. Lock the edges in wiggle-wire channels on the baseboards and the end walls, and tighten.
  8. Roll-up sides or a vent at each end are the usual ventilation. Add them before the first sunny day.

Before you start