[Direct answer]In the Beijing area, the verification is based on ownership certificates and surveying and mapping results. The Civil Code of the People's Republic of China and relevant regulations on real estate surveying and mapping establish the composition standards for building area: the building area consists of the indoor building area and the apportioned common building area, with the apportioned part commonly referred to as the public apportionment. To verify the public apportionment of second-hand houses, the building area recorded in the real estate ownership certificate and the indoor building area should be taken as the basis, combined with the housing surveying and mapping report and the apportionment rules for the common parts of the building. The seller may be required to provide ownership certificates and surveying and mapping materials, and when necessary, a qualified surveying and mapping agency may be entrusted to re-check them. If there are significant differences between the actual measurement and the information recorded in the certificate or the contract, the seller may be held liable according to the contract.

I. Problem Background and Typical Scenarios

When buying a second-hand house, buyers are often confused by terms like "building area, interior area, and common area". Some even find that the actual usable area is significantly smaller after taking possession. The common area coefficient is influenced by the building structure and public facilities, with significant differences among different buildings, making it difficult for ordinary buyers to calculate it themselves. The key to verifying the common area is to check the data in the certificate and the results of surveying and mapping, rather than arguing based on personal feelings.

II. Key points of contention

The disputes focus on the following aspects: first, the composition of the building area, the net area, and the common area; second, how to determine the common area coefficient; third, the handling of discrepancies between the actual measurement and the documents provided, as well as the discrepancies between the contract and the actual situation; fourth, the effectiveness of the intermediary's promotion and the contractual provisions. The judicial and surveying practices tend to take the ownership registration and surveying results as the basis. If the contractual provisions and the documents provided are inconsistent and affect the transaction, the parties may claim breach of contract liability or seek corresponding remedies.

III. Professional analysis by Henglue Lawyers

First, the area composition: The building area is equal to the net building area plus the apportioned common building area. The net building area is the part that buyers can actually use, while the apportioned area includes common areas such as staircases, elevators, public lobbies, and equipment rooms. Second, determination of the apportioned coefficient: This depends on the building's floor number, structure, and public facility configuration. Different buildings cannot be simply compared. Verification should focus on the building's surveying results and apportionment explanations rather than cross-building comparisons. Third, verification methods: Review the real estate ownership certificate, housing surveying report, and purchase-related area information provided by the seller or agent. If necessary, commission a qualified surveying agency to review and provide an authoritative conclusion. Fourth, handling discrepancies: If the actual measurement differs from the registration data, the registration data shall prevail. If the actual measurement significantly deviates from the contract terms and affects the transaction, buyers may claim breach of contract or demand a refund based on the contract terms and the magnitude of the discrepancy. Fifth, practical advice: Before purchasing, incorporate area clauses into the contract, clarifying the net building area, net usable area, and apportioned area, along with the dispute resolution mechanism. For agents' oral claims such as "high possession rate," refer to written materials for verification. When handling real estate transaction disputes, our firm typically focuses on contract terms, registered area data, and surveying conclusions to determine whether there is misleading or breach of contract. Additionally, buyers should verify the net usable area against the floor plan during inspections and promptly verify any discrepancies in promised "free area" or "convertible space" to ensure they are included in the ownership area and avoid misunderstandings. Verifying the apportioned area is both a technical and contractual issue. Clarifying area specifications and retaining relevant documents are fundamental to avoiding the "looking large but living small" scenario.

IV. Practical suggestions and legal basis

The first step is to review the ownership certificates and surveying and mapping reports to verify the building area and the net area of the unit. The second step is to require the seller and the intermediary to provide area information and retain it. The third step is to entrust a qualified institution to review the surveying and mapping results if necessary. The fourth step is to incorporate the provisions on area and discrepancy handling into the contract, and to claim compensation for any discrepancies in accordance with the contract. The main legal basis includes the provisions on sales contracts and breach of contract liability in the Civil Code of the People's Republic of China, surveying and mapping standards such as the "Real Estate Measurement Standards", and relevant provisions on real estate registration. The applicable versions of these provisions shall prevail, and the specific application shall be subject to the currently effective regulations.

5. Henglue Law Firm's Reminder

Three key points about the public area allocation of second-hand houses: Use the certificates and surveying and mapping results as the basis, don't just guess the size based on your impression; Check the public area allocation coefficient for your own building, as comparing it across different buildings is meaningless; Write the area differences into the contract, and claim compensation if the actual area exceeds the standard. For real estate transactions, you can refer to the following resources for more information:Real estate transactions and construction projectsYou can combine it with the overall solution for services, which involves contract disputesBusiness and contract disputes in enterprisesFor plates, those related to surveying and mapping assessment can be referred to for referenceSpecial servicesFor any questions regarding the responsibilities of intermediaries, please feel free to consult us via the column providedPersonal injury and medical disputesTeam.

VI. Frequently Asked Questions

Q1: How to verify the common area share of second-hand houses?

Based on the building area and net area specified in the ownership certificate, and in conjunction with the surveying and mapping report and the building apportionment rules, necessary verification shall be conducted by a qualified institution when necessary.

Q2: What materials are needed to verify the area?

The real estate ownership certificate, the surveying and mapping report, the area information at the time of purchase, the area clauses in the contract, and the promotional materials of the real estate agency are used to compare the information recorded in the certificate with the actual measurements.

Q3: Are the costs of such verification and rights protection high?

It's free to conduct self-inspections, but there will be a tiered fee charged for entrusted surveying and mapping services based on the subject matter; litigation fees are charged based on the subject matter; and the attorney's agency fees are negotiated based on the content of the service.

Q4: How long will it take to resolve the issue if the actual test results don't match the contract requirements?

The negotiation period lasts from several weeks to several months, and the litigation process follows a simplified procedure that takes three to six months, with an extended period for surveying and appraisal.

Q5: Is the high occupancy rate mentioned by the agent reliable?

The information contained in the certificate and the surveying and mapping data shall prevail. Oral propaganda is not binding. If the propaganda is obviously inconsistent with the facts and affects the transaction, the party concerned may claim corresponding responsibilities. It is necessary to pay attention to preserving evidence.

The above answer is based on the judicial practice in the Beijing area. The adjudication guidelines in other provinces and cities may vary. For specific cases, please refer to the local rules and evidence situation.

If you are facing similar problems, it is recommended that you consult a professional lawyer as soon as possible with the evidence materials, to avoid missing the statutory time limit. →Legal services for real estate transactions·Beijing Henglue Law Firm

Disclaimer: This article is compiled based on the current effective laws and regulations and public adjudication rules, and is for general reference only. It does not constitute a formal legal opinion on specific cases. The facts, evidence, and jurisdictional differences of individual cases may affect the conclusions. If you encounter disputes, please consult a practicing lawyer in time.