Last reviewed 1 Oct 2026 · Facts as of 1 Oct 2026 · 7 min read
Planning before construction
- Site survey and soil investigation (bearing capacity, drainage, groundwater).
- Approved design (drawings, material specification, wind speed for the location); cost estimate and approvals for subsidy (horticulture department).
- Material procurement: galvanised pipes/sections (check zinc coating and wall thickness), UV-stabilised film (check thickness, UV stabiliser and manufacturer's warranty), fasteners, aluminium profile, spring wire, nets, screens.
- Contractor or trained crew; work schedule (avoid the monsoon and high-wind season).
Construction sequence (pipe-frame polyhouse)
FormulaSteps
- Setting out — mark the boundary and the grid of columns with a theodolite or 3-4-5 triangle (Pythagoras) method; check diagonals to ensure that the plan is square.
- Excavate footings — pits at each column position of the specified size (e.g., about 0.45 × 0.45 × 0.6 m or deeper on poor soil/high wind).
- Place columns in the pits, level and plumb; cast concrete (e.g., 1:2:4 or M20) around/under them; cure for 5–7 days.
- Erect gutter-level beams, arches/trusses, purlins and cross-braces — bolt or clamp (clamps preferred to welding where the galvanising must not be damaged).
- Install gutters (GI or aluminium), down-pipes and rain-water drains.
- Fix roll-up/hinged vent frames and insect nets on the sides and roof vents.
- Fix cladding — pull the film evenly in dry, calm and cool weather (morning or evening), lock it with aluminium profile and zig-zag spring wire, avoid wrinkles but do not over-stretch; cover the sharp edges with protective tape to prevent film damage.
- Install doors (double-door vestibule), end-wall film, and entrance foot-dip.
- Lay the irrigation system — main pipeline, filters (screen/disc, sand), fertigation tank/venturi, drip laterals; fogging nozzles.
- Electrical works — panel, fans, pumps, lights, earthing (grounding) and lightning protection.
- Install cooling (pad, fans) and screens/heating if specified.
- Prepare the beds (soil sterilisation, raised beds, grow bags), install benches and trellis wires.
Quality checks during construction
| Check | Criterion |
|---|---|
| Column alignment | Plumb and in line; heights equal |
| Footing concrete | Specified mix; fully cured; anchor depth as per design |
| Bolted joints | Tightened, spring washers or lock nuts, no loose bolts |
| Galvanising | Cut ends and welds touched up with zinc-rich paint |
| Film | UV side facing out (as marked on the film); no tears, folds trapping water; tension uniform |
| Vents | Open and close smoothly; nets properly sealed |
| Drainage | Gutter slope for rainwater (about 1:200–1:250); no ponding |
| Electrical | Insulation, earthing, ratings of cables and MCBs |
Cost (indicative)
Costs vary by region, structure and year, and are based on government cost norms for subsidy; indicative ranges (check the latest cost norms): low-cost bamboo/tunnel polyhouse in the hundreds of rupees per m²; naturally ventilated polyhouse roughly in the range of ₹ 900–1,500 per m²; fan-and-pad polyhouse above ₹ 1,500–2,500 per m²; high-tech climate-controlled houses much higher. Main shares: structure (about 50–60 %), cladding and screens, irrigation/fertigation, cooling and controls, civil works and installation.
Worked ExampleExample — estimating film requirement
A 32 m × 8 m single-span polyhouse with a ridge height of 5 m, side wall height 3.5 m. Roof slope length per side m (half span 4 m, rise 1.5 m).
- Roof film area m².
- Side walls: m² (often covered with film below a net strip).
- End walls: two triangles/trapezoids, approximately m².
- Total cover m², plus 5–8 % allowance for overlaps and edges: about 600 m² of film.