[Regulatory red lines for rooftop renovation projects] Can "existing illegal buildings" in Taipei/New Taipei be repaired? Guide to avoiding pits that were demolished as soon as construction started

The misunderstanding about the "repair" of existing illegal buildings: you can't just change it however you want

Many apartments in the greater Taipei area have roof tops that have been built for decades. The iron sheets on the outside are rusty and corroded, and the wooden walls on the interior are moldy. This saves labor and causes indoor water leaks every time it rains heavily. Many homeowners and decoration contractors take it for granted: "This building is an existing illegal building that was built before 1983 (Taipei City) or 1998 (New Taipei City). It is already a subject of delayed demolition for photography and management, so if I spend money to renovate it and replace it with beautiful insulation panels or cement walls, it should be fine, right?" This is an extremely dangerous legal misunderstanding. In the law enforcement practice of the Shuangbei City Construction Management Office, the "repair" of existing illegal buildings has extremely strict lines of defense. Once the construction method crosses the boundary, the existing illegal buildings will instantly lose their qualifications for management, and will be directly judged as "new illegal buildings under construction" and will be demolished immediately.

Regulatory red lines for “renovation of existing illegal buildings” in Taipei City and New Taipei City

In order to prevent illegal construction from becoming permanent and expanding indefinitely, the Shuangbei City Government has express restrictions on the repair of existing illegal construction:

• Repair Scope Restrictions: Renovation of existing illegal structures is limited to necessary repairs for safety maintenance "within the original scale, original height, and original scope". It is absolutely not possible to increase the height, expand the floor area, or add partitions or windows.
• Structural repair ratio mine: According to the building regulations, if the repair involves "repair or change of more than half of the main structures (such as beams, columns, load-bearing walls, roof trusses, etc.)", it will be legally judged as "new construction" or "reconstruction". Once an existing illegal building is deemed to be a new one, it will automatically lose its management qualification and become a new illegal building, which will face forced demolition by the demolition brigade.
• Rigid requirements for building materials: "Non-permanent building materials" (such as wood, bamboo, rainproof plastic boards, light steel frame iron sheets, etc.) must be used during repairs. If permanent building materials such as reinforced concrete (RC), steel frame structure (H-shaped steel) or brick walls are used for large-scale replacement without authorization, it will be deemed as a new illegal construction and demolished upon inspection.

Taipei City will implement strict regulations starting from 2023: Tightening of the policy of demolition upon inspection

It is particularly important to note that in order to show its determination to rectify illegal buildings, the Taipei City Government has further restricted the flexibility for repairs of existing illegal buildings starting from 2023. The new regulations stipulate that if existing illegal buildings have structural safety concerns or carry out large-scale repairs without authorization, they will no longer be photographed and listed for management, but will be directly inspected and demolished. The New Taipei City Demolition Brigade has also adopted an iron-fisted attitude of "zero tolerance for illegal construction during construction." As long as there are scaffolding, cement trucks or cranes on the construction site for renovation and roofing, even if the owner claims that he is just repairing water leaks, if the official document from the competent authority cannot be produced, the demolition team will directly cut off water and power according to procedures and schedule compulsory demolition.

Guidelines for self-protection and pit avoidance for homeowners and construction contractors

If the dingjia must be repaired due to disrepair, serious water leakage, or structural safety damage, the homeowner and the project contractor must strictly follow the following compliance operations to avoid the risk of being demolished after being reported:

1. "Report repairs" to the Building Management Office before construction:Absolutely no work can be done secretly. The homeowner should hire a practicing architect or structural technician to take on-site photos of water leakage and structural damage, attach repair plans and structural safety appraisal certificates, and apply for "Repair of Existing Unauthorized Buildings for Inspection" to the Shuangbei City Government Building Management Office. Only after obtaining the official document of approval for inspection can you enter the construction site. This official document is the "gold medal" to resist prosecution at the construction site.
2. Retain the original structure and adopt partial construction methods: During construction, avoid dismantling the iron roof or walls all at once. It is recommended to adopt a "segmented and partial" repair method, such as replacing partially corroded iron sheets and repainting waterproof paint, rather than dismantling the entire steel frame and covering it again.
3. Changes in appearance and opening of windows are strictly prohibited: The height, length and width dimensions of the refurbished roof must exactly match the outline on the historical aerial photos. Do not push out the balcony, increase the height of the parapet, or open new windows on the exterior wall out of good intentions or convenience. These changes in appearance will not be hidden under aerial survey comparison, and they are the number one landmine for triggering reports.
4. Properly handle neighbor relations: Ninety percent of reports on existing illegal construction come from downstairs neighbors or surrounding residents. Before construction, you should proactively explain to your neighbors that it is a safe repair to completely solve the problem of water leakage on the top floor, and promise to prevent and control construction noise and dust. If necessary, you should assist neighbors in repairing walls damaged by water leakage. This can greatly reduce the chance of being maliciously reported.

Conclusion: Compliant construction is the only way to protect assets

For self-occupied homeowners or real estate investors who specialize in renovating and reselling old houses, adding illegal construction on top provides additional usable space, but it is also accompanied by extremely high legal uncertainty. When planning roof renovation projects, we must give up the old idea that "it's okay to modify existing illegal structures anyway". Only by deeply understanding the latest red lines of renovation regulations in Shuangbei and adopting a conservative construction strategy of legal reporting and partial repair of leaks can we protect this valuable asset while improving residential safety and asset value, and prevent hundreds of thousands of renovation budgets from going up in smoke.

The latest standards for catching leaks and regulatory responsibilities in Shuangbei collective housing (2025-2026 practice)

According to Article 10 of the "Apartment Building Management Regulations" of the Ministry of the Interior and the trend of civil water leakage judgments in Shuangbei District Court in recent years, most water leakage disputes in old collective housing focus on the identification and definition of "exclusive parts" and "common parts". The roof platform and the public pipes are jointly owned by all separate owners, and the repair costs should be shared by public funds or all residents in proportion to their shares according to law; if the water supply and drainage pipes inside the floor slabs on the upper and lower floors are damaged, the pipes will be borne exclusively by the users or shared by the upper and lower floors.

At the engineering and technical level, modern professional leak detection has fully introduced non-destructive scientific testing, including "FLIR high-resolution infrared thermal imaging camera" (locating temperature difference leakage paths), "high frequency moisture meter" (measuring the moisture content of deep structures) and "pipeline air pressure and water pressure pressure test" (determining whether hot and cold water pipes are leaking). During construction, do not directly apply elastic cement or oil-based paint on the wet cement layer to seal it. Otherwise, the thermal expansion of internal water vapor will quickly cause the coating to blister and peel off, resulting in more serious powdery wall cancer. The standard construction method must first completely eliminate the water source, wait until the moisture content of the cement structure drops below 8%, and then apply the negative pressure resistant silicic acid permeability crystallized waterproof layer.

Recommendations on independent certificate storage and compensation process for water leakage repair

1. Take photos and videos as evidence immediately: Use rulers to record the leakage range, frequency of water discharge, direction of water mark diffusion, and keep time stamps.
2. Written notification and coordination survey: Officially notify the neighbors through the management committee or a certified letter, and agree on a professional third-party leak detection and appraisal unit recognized by both parties to conduct an on-site survey.
3. The contract states the warranty terms: When signing the contract for the project, be sure to clearly specify the waterproofing warranty period (usually 1 year for partial repairs, and 2 to 5 years for the whole room or roof re-construction), and specify the water test acceptance criteria (such as a 48-hour water storage test in the bathroom shower area) to protect your own asset rights.