Autoconstrucción frente a contratación externa de invernaderos geodésicos: Análisis de escenarios de costo para agricultura protegida

The initial cost of the structure limits the adoption of protected agriculture among smallholders. This study estimated how the projected price of a 10 m diameter V3 geodesic structure changes from self-construction to external contracting, and which assumptions drive the difference. A layered price model (direct cost, overheads, contingencies, profit and value-added tax) was applied to three direct-cost scenarios: the reported budget (MXN 16,556.00), a corrected cutting plan of 68 steel profiles, and an additional per-worker labour correction. The original contractor budget was reconciled, margin on sales was compared with markup on cost, and a one-way sensitivity analysis, a 20,000-run Monte Carlo simulation and a scope threshold against a MXN 600/m² conventional reference were computed. The profit line of the original table (MXN 4,139.00) equals a 25% markup on direct cost, not the profit used in the subtotal (MXN 4,759.85). The contractor price was 1.67 times the self-construction cost in every scenario; profit (43.1%) and VAT (34.5%) account for most of the gap. With the corrections, the contractor price rises from 351.50 to 472.69 MXN/m² of base area; the simulated median is 457.9 MXN/m² (P5–P95: 375.7–549.6). The comparison with conventional greenhouses holds only if excluded items cost less than MXN 10,000–19,500. All scenarios are simulated, not field observations.