The four families of factors
| Family | Main factors | Order of impact on cost per m2 |
|---|---|---|
| Location | Geographic area, site accessibility, urban or out-of-town context | 15 - 30% |
| Design | Building type, size, geometric complexity, finish level | 20 - 50% |
| Site | Ground conditions, seismicity, slope, pre-existing structures | 5 - 20% |
| Market cycle | Materials and energy prices, labour market tension | 5 - 15% over multi-year cycles |
Location: the silent factor
For the same design, building in Milan or in a southern province changes the estimate by double digits: labour costs, contractors' price lists, logistics and even the reference regional price books move together. The full territorial picture, with orders of magnitude by macro-area, is in the article on north-south cost differences. Within location also lives accessibility: a historic centre site, with time restrictions, reduced storage areas and small vehicles, produces a logistics premium that no price list declares but every contractor prices.
Design: where the budget is really decided
The building type sets the band (a warehouse will never cost like a villa), but within the type the design moves the cost more than any other factor. Three levers dominate: geometric complexity (every corner, cantilever and level change is cost), the ratio of floor area to envelope (compact shapes lose less heat and cost less per usable m2) and the finish level, the most elastic lever of all. Understanding where every euro goes requires decomposing the cost by trade: structure, envelope, services and finishes, with their typical shares, are the subject of the article on the construction cost breakdown.
Site and cycle: the factors you endure
The ground is chosen once and paid for throughout the project: special foundations on poor soils, excavation on slopes, seismic zones with heavier structures. The practical rule is to invest in geology and surveys before purchase, when the information is still worth a negotiation. The market cycle, finally, is a reminder that construction costs breathe over multi-year periods: recent years' materials and energy increases shifted entire price lists, and every price source must be read with its date. That is why this guide reasons in bands and orders of magnitude, never in point prices.
Applying the factors: the same project in three scenarios
A mid-range house, reference value EUR 1,800 per m2, recalculated for three contexts. The gap between the first and third context exceeds a third.
| Scenario | Corrections applied | Resulting cost per m2 |
|---|---|---|
| Northern province, flat and accessible plot | Location +10%, neutral site | ~EUR 1,980 |
| Historic centre in central Italy, restricted access | Location +5%, site logistics +12% | ~EUR 2,110 |
| Inland southern area, sloping ground | Location -18%, excavation and foundations +10% | ~EUR 1,620 |
The exercise shows the method more than the numbers: each factor is applied as a declared percentage correction, so the budget stays traceable and debatable item by item. It is exactly the opposite of the top-down lump-sum estimate, where the corrections exist anyway but nobody sees them.
From factor to figure: the method
Recognising the factors serves one purpose: correcting the reference values before using them. The operational path (choose the base band by type, correct it for location and site, verify the scope of what the cost includes) presupposes knowing exactly how a cost per m2 is measured: reference floor area, included items, VAT and fees. That is the subject of the article on how to calculate cost per m2, which completes this cluster's reading method.
Note: the figures shown are 2026 orders of magnitude for the Italian market, for guidance only. Every project requires a specific estimate based on a bill of quantities and up-to-date regional price books.