1. The eight major land risks
| Land risk | Probability | Impact if realised | Cost and duration | How it is detected |
|---|---|---|---|---|
| A third-party challenge to the permission | 5 – 15 % | A blockage of 18 months to 3 years | Carry, interest and legal costs: 500 k€ – 2 M€ | Neighbourhood analysis and prior consultation |
| A prefectural challenge to the permission's legality | 2 – 5 % | Annulment of the permission | Refiling plus 12 to 24 months | Rigorous regulatory verification before filing |
| An undetected easement | 3 – 8 % | Total revision of the scheme | The brief reduced or moved, plus design costs | Land registry consultation and a surveyor before acquisition |
| An evolving local plan, revision in progress | Variable | The brief non-compliant with the revised plan | Refusal of permission or a revised brief | An information request to the municipality before purchase |
| Soil contamination on former industrial land | 10 – 30 % | Mandatory remediation | 50 k€ – 3 M€ according to the contamination | A phase one and phase two ground study before acquisition |
| A pre-emption right exercised | 5 – 15 % | Acquisition by the authority | The site lost, and a delay in reimbursement | Check the planning certificate before the contract |
| Preventive archaeology | 5 – 20 % | Excavation plus delay | 20 to 150 k€ plus 3 to 18 months | An archaeological risk zone in the local plan; ask the regional service |
| A contested boundary | 2 – 5 % | The scheme reduced or moved | Surveyor's fees plus delay and redesign | A joint boundary survey before acquisition, and title review |
Two risks stand out for their potentially catastrophic impact: the third-party challenge, blocking 18 months to three years and most frequent in dense urban areas; and soil contamination, whose probability is high on reconverted industrial sites, with remediation costs that can reach several million euros.
2. The third-party challenge: the most asymmetric risk in construction
The mechanism
An application to annul a planning permission is the right of any third party with an interest to act: a direct neighbour, an amenity association, a resident whose view will be affected. That right is framed by the planning code and exercised within two months of the permission being displayed on the site.
The asymmetry is striking: the cost to a claimant of lodging a challenge is almost nil, a few tens of euros of court fee plus any legal costs, while the cost to a developer of an unjustified challenge is considerable: carry costs, capital tied up, risk to the pre-sales.
The timeline
| Step | Timing | What happens | Effect on the operation |
|---|---|---|---|
| The permission displayed on site | Day 0, permission granted | The third-party challenge period starts running | No blockage yet, but the window is open |
| The challenge period | Days 0 to 60 | Any third party may lodge an application to annul | Wait before starting work on a contentious site |
| The application lodged | Within 60 days | An annulment application filed with the administrative court | The permission is suspended; work started risks being interrupted |
| First instance | 12 to 24 months | The application is examined, written submissions exchanged | The project is immobilised, the carry continues |
| Judgment | 18 to 30 months | The permission annulled or confirmed | If annulled: refile, 12 to 24 months more, or abandon |
| Appeal | + 12 to 18 months | If a party appeals the judgment | Prolonged blockage, up to four years in extreme cases |
| Final appeal, rare | + 12 months | An appeal to the supreme administrative court | Exceptional; five years of blockage in the gravest cases |
| An amicable settlement | At any moment | A financial agreement with the claimant | Unblocks quickly, at a cost of 20 to 200 k€ |
ℹ The amicable settlement: often the rational solution In many cases an amicable settlement with the claimant is economically superior to a full judicial procedure. A claimant who agrees to withdraw against compensation of 30 to 80 k€ unblocks an operation whose carry costs 50 to 100 k€ a year. The question to ask as soon as a challenge is lodged is: what is the economic value of time? If 18 months of procedure cost more than the compensation sought, settlement is rational, even if psychologically hard to accept.
3. Easements: what the site plan does not show
An easement is a burden imposed on one parcel for the benefit of another or of a public utility. It can render part of a site unbuildable, impose a set-back, or prohibit certain uses. Easements can be regulatory, as public utility easements, or contractual, agreed between owners.
- Public utility easements: they appear in the local plan. The most common are set-back easements from road corridors, wayleaves for high-voltage lines, gas mains and pipelines, and heritage protection perimeters.
- Contractual rights of way: a neighbour may hold a right of way over your land arising from an old deed. Such easements are registered but detecting them requires a full analysis of the title, something many buyers have no time to do before a contract.
- Overhead easements: high-voltage lines impose set-backs of 10 to 40 m on each side. Airport noise zones impose reinforced acoustic insulation, adding 5 to 15 % on the joinery and the envelope, and can make some programmes very hard to sell.
4. Soil contamination: the under-estimated risk of reconversion
Converting industrial sites into housing, offices or facilities is a priority of French urban policy under the objective of no net land take. But that kind of site carries a specific risk: contamination from previous activity.
Managing contamination follows three steps. A desk study, at 2,000 to 5,000 €, identifies the previous activities and assesses the risk. If the risk is real, a field investigation, at 5,000 to 30,000 €, characterises the nature and extent of the contamination. Finally a management plan sets the remediation measures, excavation, containment, in-situ treatment, whose cost can run from 50,000 € to several million.
ℹ The soil warranty clause in the contract On a site with a contamination risk, a former industrial activity, a filling station, a dry cleaner, the sale contract must include a condition precedent making acquisition dependent on a satisfactory phase two ground study. Without it, a buyer discovering contamination after completion can only proceed against the seller by proving the seller knew of it: a difficult burden and a long procedure.
5. The evolving local plan: the timing trap
A local plan is a living document: it can be revised, modified, or subject to a simplified modification procedure. An acquisition made on the basis of a plan permitting 50 dwellings can, 18 months later, face a revised plan limiting the scheme to 30 dwellings or changing the permitted use.
Protection rests on two tools: an operational planning certificate, which crystallises the applicable rules for 18 months, and direct contact with the municipality to learn of any revision procedure under way, procedures that are public but not automatically mentioned in the sale documents.
6. The land due diligence checklist
Land due diligence is the set of verifications to be carried out before acquiring a site for development. It takes two to four weeks and costs 5,000 to 20,000 € according to the complexity of the site, for an operation where the land often represents several million euros.
| Verification | Who | When | If not done |
|---|---|---|---|
| An operational planning certificate | Notary or surveyor | Before the contract | The plan unknown, a regulatory surprise at purchase |
| Reading the local plan: zone rules and maximum height | Architect | Before the contract | A non-compliant brief, refusal of permission |
| Checking for a revision in progress | The municipality, directly | Before the contract | Compliant today, non-compliant tomorrow |
| A desk study on contamination | Environmental consultant | Before the contract | Contamination found after acquisition, remediation at the buyer's cost |
| A land registry survey and boundary marking where contested | Chartered surveyor | Before the contract | A disputed boundary, the scheme reduced |
| Consulting the easements | Notary and surveyor | Before the contract | A blocking easement undetected, the scheme unachievable |
| Analysing the neighbourhood for potential objectors | Public law solicitor | Before filing the application | An unanticipated challenge, one to three years of blockage |
| Checking the archaeological zoning | Architect and the regional service | Before filing the application | Excavation imposed, delay and cost unbudgeted |
| Checking the pre-emption perimeter | Notary | Before the contract | The authority pre-empts; the site and the costs are lost |
| Analysing the chain of title | Notary | Before completion | Hidden defects in the chain; the acquisition may be voidable |
The principle of due diligence is simple: every risk identified before acquisition can be reflected in the purchase price, as a discount, or made the subject of a condition precedent. The same risk discovered after acquisition falls exclusively on the buyer, with no room to negotiate.
In summary
Land risks are the only construction risks whose scale can be total. The eight major ones run from the third-party challenge, blocking one to four years at 500 k€ to 2 M€ of carry, to soil contamination at 50 k€ to several million of remediation. The third-party challenge is the most asymmetric: almost costless for the claimant, catastrophic for the developer. An amicable settlement is often economically rational. The ten-point due diligence, planning certificate, current and evolving local plan, easements, contamination, neighbourhood, archaeology, is the indispensable preventive investment before any acquisition. Every risk found before purchase can be negotiated into the price. After purchase it falls entirely on the buyer.
The nature of the figures quoted
The percentages and amounts quoted on this page are orders of magnitude for framing, not measurements. They illustrate mechanisms and proportions, and they substitute neither for a tender exercise nor for an estimate prepared on drawings.
Articles liés
Sources: the BT construction cost indices published monthly by INSEE on its 2010 base, used to update the figures · construction cost statistics from SDES, the statistical service of the ministry responsible for construction · regulatory texts published in the Journal officiel and consolidated on Légifrance for the requirements cited.