Preventive summary application before works: recording the condition of neighbouring properties before opening a site

A heavy restructuring in a dense area (additional storeys, new basement levels, underpinning, partial demolition) exposes the project owner (maître d'ouvrage) to a category of claims that no construction warranty covers: those of the neighbours. Cracks that appeared "during the works", differential settlement of an adjoining timber-framed building, defects alleged by a neighbouring co-owners' association (syndicat des copropriétaires), loss of business of a neighbouring shop. In almost all of these cases, the debate is not about whether the defect is real but about when it appeared, and the party that cannot prove the earlier condition of the neighbouring property loses that debate. The preventive summary application before works (référé préventif), an in futurum investigative measure requested by the project owner itself before the site opens, is the tool that fixes this evidence and that, incidentally, deters some opportunistic claims. This guide sets out its basis, its scope, the drafting of the expert's mission, the timetable for applying and its real limits.

What the preventive summary application covers, and what it is not

A textual basis shared with the summary application for an expert appraisal, an opposite logic

The preventive summary application has no text of its own. It relies on Article 145 of the French Code of Civil Procedure:

"If there is a legitimate reason to preserve or establish, before any trial, the evidence of facts on which the outcome of a dispute may depend, investigative measures that are legally admissible may be ordered at the request of any interested party, on application or in summary proceedings."

The kinship with the classic summary application for an expert appraisal ends there. In its usual configuration, Article 145 CPC is the weapon of the victim: a buyer discovers water infiltration, a co-owner notes defects in the façade, a project owner suffers poor workmanship, and each applies to the president of the judicial court (tribunal judiciaire) to have an expert appointed after the damage has occurred. The measure is remedial, directed to establishing a liability that is already potentially engaged. The legitimate reason, the framing of the mission and the cost of the remedial measure are set out in our article on the summary application for an expert appraisal under Article 145 of the Code of Civil Procedure.

The preventive summary application reverses this logic on three points. The initiative belongs to the person who is, by hypothesis, the future defendant: the project owner. The fact to be established is not a defect but the absence of a defect, that is, the initial condition of the neighbouring buildings. And the measure is requested before any damage, which implies a procedural timetable constrained by the site programme and not by the discovery of a loss.

This reversal has an immediate practical consequence: the legitimate reason is not demonstrated in the same way. It is not a matter of setting out a defect, but of establishing the probability of a future dispute, which is inferred from the nature of the planned works, the configuration of the neighbouring buildings and the density of the urban fabric. A serious application file therefore includes the descriptive notice of the works, the site and section plans, the description of the construction methods envisaged (micropiles, Berlin or diaphragm walls, groundwater lowering, underpinning), any geotechnical studies already available and the survey of party walls.

What a report by a commissaire de justice cannot achieve

Many project owners are content with a report on the condition of neighbouring properties drawn up unilaterally by a commissaire de justice (bailiff) before the start of works. The step is not useless, it is insufficient. A report that is not adversarial has, as regards a neighbour who was not called to it, only the value of an item of evidence subject to the free assessment of the judge. The neighbour can always argue that the person making the report did not have access to the relevant parts, that the photographs are partial, that the cracks recorded post-date an old, undocumented defect.

The judicial preventive expert appraisal has a different effect. It is adversarial within the meaning of Articles 16 and 160 et seq. of the Code of Civil Procedure, it is enforceable against all the parties duly summoned to the proceedings, and the appointed expert remains seised for the whole duration of the works. This last point is often underestimated: when an incident occurs during the works, the project owner does not have to start new proceedings. It applies to the judge responsible for supervising expert appraisals for an extension of the mission, and the expert already on site acts within time limits that cannot be compared with those of a new appointment. On the conduct of site visits, the parties' written observations (dires) and the challenge to the draft report, see our analysis of the conduct of judicial property expert appraisal operations.

For high-value assets and long-running sites, the combination of the two tools remains the most robust: a report by a commissaire de justice on the roads, public spaces and premises to which access is refused, and a judicial expert appraisal for everything that is accessible and can be examined on an adversarial basis.

The risk that the mechanism neutralises: liability by operation of law

Article 1253 of the Civil Code since the Law of 15 April 2024

The theory of abnormal neighbourhood disturbances, long purely case-law based, is now codified. Law No. 2024-346 of 15 April 2024 aimed at adapting the law of civil liability to current issues inserted into the Civil Code an Article 1253 worded as follows:

"The owner, the tenant, the occupant without title, the holder of a title whose main purpose is to authorise occupation or use of land, the project owner or the person exercising its powers who causes a disturbance exceeding the normal inconveniences of neighbourhood is liable by operation of law for the resulting damage."

The project owner is expressly covered by the text. Liability is strict: the claimant neighbour has no fault or breach to demonstrate. It is enough to establish a disturbance, its abnormal character and a causal link with the works. Force majeure and the act of a third party or of the victim remain the only classic grounds of exoneration, to which is added the prior-occupation regime provided for by Article 1253 for certain pre-existing activities, which is of no practical relevance to a restructuring site.

The result is an evidential asymmetry that the preventive summary application corrects. Without a documented initial condition, the project owner has to prove a negative, namely that the cracks relied on already existed. With an adversarial initial condition, the burden shifts: it is for the neighbour to demonstrate the worsening against a reference that the neighbour has validated, or at least in which the neighbour was invited to take part.

The spread of liability towards the builders

Case law has long accepted that the builders working on the site are occasional neighbours and can be pursued directly by the neighbouring owner on the basis of abnormal neighbourhood disturbances, in the same way as the project owner. The latter has, in return, recourse against the contractors and the other parties engaged in the works. These recourse actions are not played out on the ground of strict liability but on that of fault or contract, which requires the precise identification of the technical failing at the origin of the defect: unsuitable excavation method, defective shoring, vibrations exceeding the contractual thresholds, uncontrolled groundwater lowering.

This is precisely what a well-drafted preventive expert mission makes possible. The expert having reviewed the construction methods in advance and followed their execution, the project owner has, on the day of the claim, technical material produced on an adversarial basis in the presence of the contractors. Failing that, the claim comes up against findings reconstructed after the event, which are always more fragile.

Identifying the neighbours to be summoned

The most frequent and most costly flaw in a preventive summary application before works is the omission of a party. An expert appraisal is enforceable only against those who have been duly summoned to it. An omitted neighbour keeps all of the neighbour's arguments, and the order obtained will not be enforceable against that neighbour, whatever the quality of the expert's work.

The scope is built from a land survey and not from a visual assessment. It generally includes:

• the owners of the adjoining plots and of the buildings located within the geotechnical zone of influence of the works, which goes beyond physical contact as soon as there is deep excavation, groundwater lowering or piling;
• the neighbouring co-owners' associations, summoned in the person of their property manager (syndic), to which are added, where private parts are concerned, the co-owners individually;
• the tenants and operators, in particular commercial tenants on the ground floor, whose loss of business is distinct from that of the landlord;
• the utility concessionaires and the managers of networks and infrastructure: electricity and gas distributors, water and sewerage operators, telecommunications operators and, depending on the location, the operators of underground transport networks;
• the local authority in respect of the roads, the roadside trees and the street furniture;
• where applicable, the architecte des Bâtiments de France (architect responsible for protected heritage) not being a party, the owner of a neighbouring protected building, whose sensitivity justifies specific treatment in the mission.

Prior consultation of the works project declarations and declarations of intent to commence works, provided for by Decree No. 2011-1241 of 5 October 2011 on the execution of works near certain underground, overhead or underwater structures, provides a reliable map of the network operators to be brought in. It does not remove the need for a mortgage register search and a check on the real ownership of the neighbouring plots, co-ownership registers often lagging behind recent transfers.

Where a party is identified late, compulsory intervention during the expert appraisal remains possible under the conditions of Articles 331 et seq. of the Code of Civil Procedure, by summons seeking a declaration that the order applies to that party as well. It is better to anticipate this: a party called after the completion of the structural works will not have taken part in the initial survey, which deprives the mechanism of most of its effect.

Building the expert's mission: the core of the mechanism's effectiveness

The value of a preventive summary application is decided in the drafting of the mission, not at the hearing. A standardised mission produces a standardised report, that is, a dated photograph album, useful but thin. A mission built around the construction methods chosen produces a tool for steering the site.

The initial survey

The foundation remains the report on the condition of the neighbouring properties: description of the façades, gable walls, party walls, floors, cellars, courtyards and fences, with the recording and location of cracks, misalignments, deformations and pre-existing defects. Two technical requirements deserve to be expressly requested from the judge, because they do not always appear in standard missions: the installation of crack gauges on significant cracks, with an adversarial recording of their initial opening, and the establishment of a topographical and levelling reference allowing differential settlement to be measured later. Without a levelling reference, settlement of a few millimetres will be impossible to demonstrate, in either direction.

On older buildings, the mission benefits from providing for an examination of the load-bearing structures and existing foundations where access allows, as well as a survey of the condition of the shared underground services, a classic source of delayed disputes where a leak is revealed months after the end of the works.

The opinion on methods and the monitoring of the works

The second branch of the mission turns the preventive expert appraisal into a prevention mechanism. The expert is invited to review the planned construction methods, the geotechnical studies, the phasing and the measures for protecting neighbouring properties, and to make any useful observation before the start of works. This phase has a direct operational effect: it is not unusual for it to lead to a change in the excavation phasing, the strengthening of shoring, the replacement of piling by a drilling technique, or the imposition of additional instrumentation.

Monitoring must then be provided for: periodic visits timed to the sensitive phases, adversarial readings of the gauges and levelling points, and above all an urgent referral clause allowing any party to alert the expert in the event of an incident, the expert being required to attend within a short time. It is this mechanism that prevents a defect that appeared in week 12 from being recorded only in week 40.

The points generally omitted

Three elements deserve to be added where relevant. Vibration measurements, with a threshold of particle velocity not to be exceeded and continuous instrumentation on the most sensitive structures, because otherwise the debate on vibrations is purely declaratory. Piezometric monitoring in the event of groundwater lowering, since defects linked to a change in the level of groundwater may appear at a distance from the site and long afterwards. Finally, the exit survey, which must be expressly provided for in the mission: a preventive summary application that does not close with a final adversarial report leaves open the whole period after the last visit.

The decision timetable: when to apply to the judge

Before any trial, before any defect

Article 145 of the Code of Civil Procedure requires that the measure be requested before any trial. A trial judge already seised of the dispute neutralises the route of the preventive summary application. A simple rule follows for the project owner: the window closes as soon as a neighbour issues proceedings, and it closes practically as soon as a defect appears, since the report then becomes remedial and loses its value as an initial reference.

Anticipation must therefore be built into the project timetable in the same way as the clearing of challenges to the building permit. The application requires a technical file already in place, a complete land identification of the neighbouring properties and the service of summonses on a sometimes large number of defendants. The summary hearing, the appointment of the expert, the deposit payable by the applicant under Article 269 of the Code of Civil Procedure, then the organisation of the first expert meetings and the actual carrying out of the on-site reports take several months. Starting the process after the works contracts have been signed exposes the project to a delay in the start order, the cost of which generally far exceeds that of the procedure.

The interplay with insurance and financing

The preventive summary application is rarely a legal requirement. It is frequently a contractual requirement. Contractors' all-risks policies and cover for damage to existing and neighbouring property often make their activation conditional on a prior adversarial survey. Lenders financing a heavy restructuring, in particular where a discounted asset is being taken over, regularly include it among the conditions precedent or the borrower's undertakings. Neglecting this point amounts to creating an uninsured exposure on the most volatile risk item of the site. The scope of this policy and its interplay with the structural damage insurance (dommages-ouvrage) are covered separately in our article on the real cover of contractors' all-risks insurance.

The cost of the preventive expert appraisal is therefore budgeted upstream, within the project owner's costs, and not as a procedural contingency. It is weighed financially against an exposure to compensation which, in a dense urban fabric, relates to structural repairs, commercial loss of business and, in the most serious cases, a stop to the works ordered in summary proceedings on the basis of Article 835 of the Code of Civil Procedure.

What the preventive summary application does not settle

The tool has limits that must be stated clearly, because a project owner who regards it as a discharge reads it wrongly.

The order does not extinguish any liability. It organises the evidence, it decides nothing on the merits. A neighbour who demonstrates a worsening against the initial condition will obtain compensation, and the expert report will then be used against the project owner with the same force with which it would have served the owner.

The survey covers only physical damage. Nuisances affecting enjoyment of the property (noise, dust, perceived vibrations, restricted access, loss of view or sunlight during the works) follow a different logic. They are assessed in the light of duration, intensity and compliance with the rules on site noise, in particular Articles R. 1336-10 et seq. of the Public Health Code and the applicable prefectural or municipal orders. A neighbouring business that claims loss of business will not be effectively answered by an album of cracks. Where this risk is identified, the mission must include a specific section recording the nuisances and the access conditions, visit by visit.

Finally, a neighbour's refusal of access remains a real difficulty. The expert then draws up a report of default (procès-verbal de carence). The project owner may apply to the judge for an order for access, where appropriate under a penalty payment, case law also accepting a right of temporary access (tour d'échelle) for a person who has to carry out necessary works on his or her own land. But these incidents consume time. In practice, the report of default is a serious mitigating element on the day the same neighbour claims compensation for defects whose initial recording the neighbour prevented, without amounting to an automatic exoneration.

An economic choice as much as a legal one

The preventive summary application before works is not a file formality. It is an instrument for shifting the burden of proof, and as such an investment item whose return is measured against the site's exposure to compensation. On a project in a dense urban fabric, with underpinning, deep excavation or old party walls, the absence of an adversarial survey does not translate into a saving but into a deferred cost, increased by the risk of a stop to the works and the loss of recourse against the contractors.

Two operational recommendations follow. First, treat the application as a milestone in the programme, positioned after obtaining a building permit free of challenge and before signing the works contracts, and not as a reaction to the first claim. Second, do not settle for a standard mission: have the mission drafted by a lawyer working with the design team and the geotechnical consultancy, including the reference levelling, the vibration instrumentation, the periodic monitoring, the urgent referral and the exit survey. It is the mission, not the order, that determines the defensive value of the mechanism.

Frequently asked questions

Is a preventive summary application mandatory before opening a site? No text imposes it on the project owner. The obligation most often arises from contract: contractors' all-risks policies and neighbouring-property cover that make their activation conditional on a prior adversarial survey, undertakings given to a lender, or provisions of the special administrative terms. In practice, on a heavy restructuring next to adjoining buildings, dispensing with it amounts to accepting an uncovered exposure to abnormal neighbourhood disturbances, which Article 1253 of the Civil Code, resulting from Law No. 2024-346 of 15 April 2024, makes a liability by operation of law.

What is the difference from a classic summary application for an expert appraisal under Article 145 CPC? The textual basis is identical: Article 145 of the Code of Civil Procedure. The purpose is reversed. The classic application is brought by the victim after a defect has appeared, to establish liability. The preventive application is brought by the project owner before the site opens, to establish the initial condition of the neighbouring properties and to secure defensive evidence. It therefore requires an application before any trial and before any damage occurs.

How much time should be allowed between the decision to apply to the judge and the actual start of works? One must allow for the complete land identification of the neighbouring properties, the preparation of the technical file, the service of summonses on all the defendants, the summary hearing, the deposit provided for in Article 269 of the Code of Civil Procedure, then the first expert meetings and the on-site reports. On a project involving several neighbouring buildings, co-owners' associations and network concessionaires, the whole is counted in months. The process must be started before the works contracts are signed.

Who bears the cost of the preventive expert appraisal? The deposit is payable by the applicant, and therefore by the project owner, under Article 269 of the Code of Civil Procedure. The cost is budgeted within the project owner's costs. At the stage of later proceedings on the merits, its final allocation may be discussed as costs (dépens) or irrecoverable costs, but that is not the working assumption to adopt when the budget is set.

Can a neighbour refuse access to the appointed expert? Materially, yes. The expert then draws up a report of default. The project owner may apply to the judge responsible for supervising expert appraisals or to the summary judge to obtain access, where appropriate under a penalty payment. The refusal does not amount to automatic exoneration from liability, but it is a serious defence element where the same neighbour later claims compensation for defects whose initial recording the neighbour prevented.

Should the tenants of neighbouring buildings be summoned, or only the owners? Both, where the premises are occupied. The expert appraisal is enforceable only against the parties duly summoned. A commercial tenant on the ground floor will claim a loss of business distinct from that of the landlord, and Article 1253 of the Civil Code expressly covers the tenant and the occupant among those entitled to bring an action for abnormal neighbourhood disturbances. Omitting the operator leaves in place the highest compensation risk in the file.

Does the preventive summary application cover noise nuisance and the loss of business of neighbouring shops? Not in its standard version, which is centred on the report on the condition of neighbouring properties and physical damage. These nuisances affecting enjoyment are assessed in the light of their duration and intensity, and of compliance with the rules on site noise, in particular Articles R. 1336-10 et seq. of the Public Health Code. Where the risk is identified, the judge must be asked to include in the mission a section recording the nuisances, the access conditions and the activity of the neighbouring shops, noted at each visit.