Purchasing the land is the heaviest and least reversible commitment in a property development operation. A misjudgement at this stage affects the entire project, from the building permit application through to the delivery of the homes. This is why professionals devote several weeks, sometimes several months, to studying a plot of land before signing a preliminary sale agreement. This phase, largely invisible to the general public, relies on a structured method that cross-references four families of risk: regulatory, technical, financial and legal.
The first question is not the price of the land, but what can actually be built on it. The developer analyses the Local Urban Plan (PLU): zoning, maximum height, ground coverage, parking rules, green space requirements and social housing quotas. They also check public utility easements, reserved sites, protection perimeters around historic monuments and any development guidelines likely to constrain the project.
This regulatory reading determines the actual buildability, in other words the floor area that can genuinely be delivered. In dense, heavily regulated markets, a property developer in Île-de-France also factors in the local authority's stance: a project that complies with the PLU but is poorly received by the municipality will face a more complicated review process, and may become bogged down entirely.
Studying a plot combines regulatory, technical, financial and legal analysis.
Land that is buildable on paper may prove expensive to build on. Geotechnical surveys (G1 then G2 missions) provide information on the soil's bearing capacity, the presence of swelling clays, cavities or a high water table, all of which push up foundation costs. The developer also examines the site's history: former industrial activity may require remediation, sometimes costing hundreds of thousands of euros.
To this must be added natural risks (flood risk prevention plans, clay shrinkage and swelling), preventive archaeology requirements, and the capacity of existing networks (roads, drainage, electricity) to serve the future development.
All these elements feed into the developer's financial appraisal, a reverse calculation that starts from projected turnover (home sales at local market prices) and then deducts construction costs, professional fees, taxes, financing and marketing costs, along with the expected margin, generally between 8 and 10% of turnover. The balance corresponds to the acceptable land cost, in other words the maximum price the developer can offer for the plot.
This calculation is then subjected to sensitivity testing: what happens to the operation if sale prices fall by 5%, if construction costs drift upwards, or if sales stretch out over an extra twelve months? An operation that does not withstand these downside scenarios is abandoned, however attractive the land may appear.
A developer never signs an immediate outright purchase. The preliminary sale agreement includes conditions precedent: obtaining a building permit free of any third-party appeals, a sufficient level of pre-sales (often 40 to 50% of units reserved off-plan), and bank financing approval. This mechanism postpones the acquisition until the main uncertainties have been resolved.
Assessing a plot of land therefore amounts to quantifying uncertainties and buying only once the residual risk becomes acceptable. This discipline explains why a large majority of the sites studied by developers never lead to an acquisition, and why the operations that are seen through rest on months of prior analysis.
