In July 2025, Liu Ming, a junior student from Sichuan, decided to rent an apartment near his school with his girlfriend to prepare for civil service exams. This was their first time renting, and after seeing rental advertisements near the campus, they hastily viewed properties for just one day before signing a lease contract.

The apartment was new but had a pungent odor. Some furniture still had unopened packaging, the washing machine's water pipes weren't connected, and plastic films remained on the refrigerator and mattress. The agent told them the house wasn't newly renovated, had been aired out for at least six months, and had previous tenants. Despite their doubts, they rented the room for 950 yuan per month, spending over 3,800 yuan including utilities, management fees, and deposits. They didn't realize they had fallen into a "string room" trap.

"String" originally comes from Chongqing dialect, meaning broker or middleman. "String rooms" refer to properties where speculators acquire old or bare houses at low prices, renovate them at minimal cost, then rent them out at high prices as supposedly well-decorated units to profit from the price difference. These properties typically have issues like excessive formaldehyde levels.

On the day Liu Ming signed the contract, the landlord didn't appear. The next day, after adding the landlord's social media, he discovered posts about acquiring bare houses and quickly renovating them for rental. Liu Ming then realized he had been deceived into signing a lease for a string room packaged by a sub-landlord.

Liu Ming's experience isn't isolated. Also in July, the incident "Hangzhou man pays 60,000 yuan monthly rent, moves into formaldehyde-contaminated house, develops health problems" became the third trending topic on Weibo with over 210 million views.

According to third-party data platform New Red Data, by the end of August 2025, the total views of string room topics on Little Red Book reached 141 million, with 14,700 total participants and 19,700 new interactions in the past 30 days.

Since 2024, mainstream social media platforms have seen daily complaints from tenants about renting string rooms. Common keywords in these posts include "recent graduate," "urgent rental needs," "exquisite decoration," and "minimalist style."

A frontline employee from a leading rental agency explained that the current market downturn has left many old houses unrented. Consequently, numerous sub-landlords and investors target these cheap, run-down properties, renting them at low prices and repackaging them with minimalist, well-decorated aesthetics before re-renting. Most of these properties have formaldehyde issues.

Dai Guangming, North China Operations Manager at Magic Cube Apartments, believes string rooms achieve excessive profits through short-term cash flow and cost compression. For a 50-square-meter apartment, renovating in the minimalist style popular with young people costs only a few thousand yuan (without considering environmental standards), yet can command rents 20-30% above market rates.

When young people develop health problems from string rooms, they not only lose money and health but also face lengthy rights protection battles.

**"He told me to get treatment if I'm sick"**

Since 2024, recent graduates have increasingly fallen into string room traps. With limited budgets and little rental experience, they seek comfortable, attractive homes. Despite warnings and horror stories shared by predecessors on social media, they still unknowingly become victims.

In June 2024, after graduating from university, Wang Lei rented a room in Xiamen's Wuyuan Bay Zhongzhai North Court for 3,000 yuan per month. Recalling the rental process, his strongest feeling was chaos. "I saw rental listings on TikTok and Little Red Book, contacted what seemed to be a nth-hand agent, and was arranged to view properties with another young person. He walked ahead in slippers while I was led around like livestock."

Upon entering the building, drilling sounds were constant, with construction boards still laid out everywhere and workers constantly coming and going. However, the agent assured him that his target room had been aired out for a long time, and that he himself lived in the building. To further reassure Wang Lei, after he left, the agent bought a simple circular self-testing kit to check the room, with results showing formaldehyde levels within normal limits.

Just one week later, Wang Lei was hospitalized with high fever. A testing agency's report showed that formaldehyde, TVOC, benzene, toluene, and xylene all exceeded standards to varying degrees.

When Wang Lei confronted the sub-landlord, the response was dismissive: "All furniture contains formaldehyde. Should everyone stop living in houses? Formaldehyde releases slowly - how could it hospitalize you in one week? How would construction workers be able to work?"

Subsequently, the sub-landlord began deflecting responsibility, sometimes claiming the house had no wooden furniture so formaldehyde couldn't exceed standards, sometimes offering to move Wang Lei to another property, and sometimes demanding Wang Lei first sublet the current room. Eventually, the response became: "You have psychological problems to begin with. Have you faced this? Get treatment if you're sick."

The sub-landlord's attitude left Wang Lei both angry and helpless. He felt like a "rental house pothos plant," suffocating every night.

Not only recent graduates fall victim to string rooms; experienced workers also get trapped. In late October 2024, due to job relocation, Xu Tian and her husband decided to move from Guangzhou to Hangzhou with their two cats. After arriving, they boarded the cats at a pet store and spent two days viewing properties before deciding on one.

"We thought keeping the cats at the pet store too long after changing environments wasn't good, so we wanted to settle quickly. Plus, our previous direct-landlord rental experiences were pleasant, so we weren't very cautious," she said.

Her husband contacted the landlord through Douban and WeChat video channels. This was a newly delivered building from over a year ago, meeting their requirements for a "clean, safe, short-commute" home. Upon entering, they found the room had basic furniture but was very sparse, with windows wide open. Unfamiliar with Hangzhou's rental market, they believed the landlord's explanations and paid over 10,000 yuan in deposits alone, including rent, security deposit, pet deposit, and utilities.

Xu Tian's husband has naturally heightened sensitivity to odors. On their first night, he detected strange smells, experienced breathing difficulties, and didn't improve even after taking medication. "Fortunately, he's sensitive to odors, otherwise who would be responsible if we developed serious illnesses?" she said.

They purchased formaldehyde testing equipment and simple circular self-testing kits online. Testing revealed that while values fluctuated, they were very close to exceeding standards. They immediately moved out and discussed refunding remaining rent with the landlord, only to be told not a penny would be refunded.

The landlord's harsh attitude made her realize they'd likely need to go to court. She hired an agency for on-site testing with full video documentation. Results showed formaldehyde and TVOC levels exceeding standards to varying degrees.

Yu Jiayi, a lawyer at Jiangsu Mainland Law Firm specializing in rental disputes, has handled over 300 rental disputes, nearly 80 related to string rooms. She observes that properties rented by sub-landlords, small agencies, and small rental companies are most prone to string room problems and require special caution.

**"I work during the day and organize materials until 3-4 AM"**

When negotiations fail, tenants can only seek help from legal authorities and regulatory agencies. ICCRA Housing Rental Industry Research Institute Director Zhao Ran summarizes that if tenants' self-negotiation fails, they can call 12345 to complain to their city's housing construction department, urban management department, or street offices. When necessary, they can consider legal action or apply for legal aid.

But when reaching the legal litigation stage, tenants discover more pitfalls ahead.

The first trap lies in contract terms. When renting, Xu Tian didn't have time to carefully review the thick stack of contracts the landlord provided. She later discovered the contract not only failed to comply with Hangzhou regulations but contained many unfair terms, such as no subletting allowed, high compensation fees, and absolving landlord responsibility.

Yu Jiayi summarizes that if contracts contain clauses like "landlords bear no legal responsibility for formaldehyde exceeding standards," the property is likely a string room, though this is relatively rare. More common are restrictive clauses with high compensation fees designed to intimidate tenants.

"Actually, writing such clauses is pointless - both situations are illegal, just bullying tenants who don't understand the law," she said.

The second trap lies in contract termination. After negotiations failed, Xu Tian chose to report to police. Under police witness, she informed the landlord of the modified door code, emphasizing they had moved out and wouldn't return. This was advice from her lawyer friend to prevent landlord deception about not having recovered the property.

"How he handles the house afterward is none of our business. If he claims in court that the house can't be rented due to our reasons, that's his malicious expansion of losses," she said.

Multiple interviewed tenants mentioned that when moving out, they must remember to send the landlord a message indicating they've moved, which courts use as evidence for determining move-out dates.

The third trap lies in landlord identity. Only when deciding to report to police and inquiring with property management did Xu Tian discover that the contract signatory wasn't the actual owner but a sub-landlord. The contract also didn't include the sub-landlord's ID number, essential material for filing a case.

She could only organize available evidence to apply for case filing at court, obtain a court certificate, then go to the police station to retrieve the sub-landlord's ID number.

Yu Jiayi once discovered while guiding a client's lawsuit that the sub-landlord had intentionally written one digit of their ID number incorrectly. She had to help retrieve household registration information, spending over half an hour with police officers trying different numbers to find the correct one.

She emphasizes that tenants must carefully verify landlords' ID cards, property certificates, and addresses when renting. Without ID numbers, they can't sue, leaving them helpless even when wronged.

Even with lawyer friends helping review lawsuit materials, the tedious paperwork exhausted Xu Tian and her husband. "Without my friend explaining and helping organize materials, I wouldn't know where to start," she said.

Besides organizing chat records, test reports, and transfer records into complete evidence chains and burning video materials onto CDs, there were many unfamiliar legal document formats requiring attention. Many nights, she and her husband worked until 3-4 AM, then worked normally during the day.

From filing to court hearing took nearly half a year. During this period, the sub-landlord refused direct communication, leaving Xu Tian only able to wait. She tried finding a Hangzhou lawyer to represent the case but learned that for lawyers, these disputes involve low amounts with correspondingly low fees, making hired legal representation uneconomical for both parties.

Fortunately, the court hearing went smoothly. After reviewing Xu Tian's organized evidence, the judge ruled in her favor. The sub-landlord must compensate 21,000 yuan, including deposits, remaining rent, testing fees, and penalties, with the sub-landlord bearing most of the over 400-yuan litigation costs.

However, as of publication, Xu Tian informed that she still hasn't received the sub-landlord's compensation and applied for forced execution in late August.

Wang Lei also chose to recover his rent through litigation. Although he spent 1,000 yuan consulting lawyers initially, organizing materials, forming evidence catalogs, and researching legal regulations required his own exploration. This not only consumed significant time but brought enormous psychological pressure, causing insomnia and trembling hands.

"I don't know what I'll face in court. I don't have a lawyer, just a pile of messy materials that I don't know are sufficient, and nothing else," he said.

Due to unfamiliarity with relevant laws, he confused rental disputes with environmental pollution tort concepts, which the judge corrected in court.

Yu Jiayi believes string room lawsuits aren't difficult to win. As long as tenants can provide legally valid CMA test reports (China Metrology Accreditation - reports with CMA seals can be used for product quality evaluation, results, and judicial identification), proving the property is a string room isn't difficult.

She reminds that after test reports show formaldehyde exceeding standards, tenants should promptly notify landlords in writing about contract termination, clearly stating that the reason for moving out is formaldehyde exceeding standards and landlord breach of contract. These are evidence needed for future lawsuits.

However, compensation amounts may not meet tenants' expectations. Usually, only remaining rent, deposits, and testing fees are awarded to be borne by landlords. Yu Jiayi explains that judges have discretionary power, generally used to determine whether hotel costs should be covered by the other party, but medical expenses generally can't be compensated.

"Because hospitals can't prove causal relationships between illness and formaldehyde exceeding standards. As for other unrealistic demands like lost wages, taxi fees, etc., I generally tell tenants directly that their ideas are unlikely to be realized," she said.

**How to correctly test formaldehyde and preserve evidence?**

Whether for residential health or evidence preservation, effectively testing rental property formaldehyde levels is crucial. The "GB/T 18883-2022 Indoor Air Quality Standards" issued by the State Administration for Market Regulation and Standardization Administration of China stipulates that formaldehyde detection standards require one-hour average content not exceeding 0.08 mg/m³.

Shi Bao has been engaged in formaldehyde detection and prevention for nearly 15 years. He told that formaldehyde's volatilization cycle is 15 years, with the outbreak period being the first 2-3 years, making its harm to human health more severe than other chemical substances.

Shi Bao reminds that when choosing formaldehyde testing agencies, select those with local laboratories and CMA certification verifiable on local market supervision administration websites, paying attention to verifying basic information like CMA certification certificate validity periods. These agencies typically charge 500-800 yuan per testing point (usually one room).

During testing, landlords must be notified in advance, with both parties present simultaneously, or videos must be taken for absent parties. He further points out that formaldehyde testing agencies only handle testing, not formaldehyde removal, and vice versa. If tenants want formaldehyde removal services, they should choose agencies with local laboratories and judge professionalism by whether contracts specify warranty periods or "no effect, money back" guarantees, and whether staff wear uniform work clothes and shoe covers. Formaldehyde removal agencies typically charge 20-30 yuan per square meter.

A large rental agency operations staff member warns tenants that simple circular self-testing kits purchased online may not provide accurate results. If self-testing kits are placed on balconies, wind can cause color changes.

Currently, the market has some non-professional formaldehyde testing methods whose scientific validity and authority can't compare with professional testing agencies.

Shi Bao believes there may be "false exceeding standards" situations. He explains that simple formaldehyde testing instruments are greatly influenced by external factors, with possibilities of inaccurate readings or value manipulation. Additionally, formaldehyde testing requires rooms to be sealed for 12 hours with room temperature controlled around 26°C to simulate living environments and detect results most relevant to actual residential conditions. Some testing extends sealing time, raises temperatures, or uses other methods making indoor environments inconsistent with actual living situations, offering little reference value.

**If you're renting for the first time, I have these suggestions**

If he could return to the moment of viewing properties, Wang Lei would tell his former self following the agent: don't rent from sub-landlords and small agencies.

After beginning rights protection, he tried various methods including reporting to police, petitioning, calling 12315 complaints, and litigation. He even went to the community entrance to tell all entering and exiting tenants about his experience.

He summarized several property viewing insights: first, check agent qualifications and preferably choose agencies with physical stores; second, focus on checking whether renovation materials, mattresses, and cabinets are environmentally friendly, requesting test reports from landlords or agents when necessary; third, avoid wishful thinking - if you see beautifully renovated properties without signs of habitation, skip them directly rather than hoping to rent something new.

If unfortunately renting a string room, his advice is: if the amount involved is small, just move out directly and learn from the experience. But if the amount is substantial, actively pursue rights protection through various channels.

"If you don't protect your own rights, no one will help you," he said.

Yu Jiayi also summarizes that tenants should try to view properties during summer or midday and extend viewing time. Besides checking whether home decoration and furniture are environmentally friendly, they can ask neighbors about rental situations to gather multiple perspectives and avoid renting string rooms.

Dai Guangming summarized a method to avoid renting formaldehyde-contaminated houses: "four checks and one smell": check renovation traces (don't live in overly new ones); check material environmental grades (don't live in low-grade ones); check air quality test reports (don't live where none can be provided); check contract terms for clauses about penalty-free refunds if air quality doesn't meet standards; smell odors - if there are pungent smells or heavy artificial fragrances, problems may exist.

Regarding string room issues, some rental agency operations executives mentioned that after 2019, leading platforms invested heavily in ensuring residential safety. Now, rental air quality issues are basically compliant.

Yu Jiayi also suggests tenants should try to choose leading rental agencies when renting because they have platform endorsement and face stricter regulation.

On August 27, searching "housing rental contract disputes" and "formaldehyde" on China Judgments Online returned 1,303 related documents, with leading rental platform agencies totaling about 70 documents, approximately 5% of the total.

Dai Guangming states that when Magic Cube rents new apartments, they post each room's CMA test report on doors while informing tenants about each room's renovation time and post-renovation formaldehyde removal status.

Ziroom responded that all newly renovated properties undergo air quality testing and are only listed after passing. If tenants have concerns about living space environment, housekeepers will visit within 24 hours to confirm situations and coordinate relevant agencies for testing verification. During verification, Ziroom also provides necessary proper accommodation for users.

According to reports, Beike Peace of Mind Rental now adheres to whole-collection, whole-rental principles with strict standards in property acquisition. For properties suspected of exceeding formaldehyde standards, they proactively conduct professional formaldehyde testing and take corresponding measures like renovation and vacant ventilation based on results to eliminate "formaldehyde room" risks.

On July 21, Xinhua News Agency released the State Council's "Housing Rental Regulations," stipulating that rental housing should comply with legal, regulatory, administrative, and mandatory standards for construction, fire safety, gas, and interior decoration, without endangering personal safety and health. Housing rental agencies with such situations face fines of 20,000-100,000 yuan.

Yu Jiayi noted that the Regulations only target housing rental agencies, not individual sub-landlords. Zhao Ran believes the Regulations have clarified bottom lines, with the key being implementation, particularly government-platform co-governance.

He believes future improvements to rental environments could include establishing blacklists and credit punishment systems, promoting rental registration and transparent housing structure information, and creating public legal aid and one-click reporting channels.

(At interviewees' request, Wang Lei, Liu Ming, and Xu Tian are pseudonyms)