Leave the repairs and renovations of condominiums and apartments in Kohoku, Yokohama City to Kakeru Koumuten Co., Ltd.!

Large-Scale Renovations for Condominiums, Apartments, and Buildings in Kohoku Ward, Yokohama

Large-scale repair work that can be handled in Kohoku Ward, Yokohama

Large-scale repairs are not just “exterior painting” or “waterproofing,” but rather a comprehensive repair of the entire building’s deterioration while scaffolding is in place. At Kakeru Koumuten, we can handle all of the following work in-house, ensuring clear responsibility and coordination of the process.

Scope of Major Repairs Determined from Building Diagnosis

It is not always necessary to carry out all of the above works. The extent of the work will be determined based on the results of the building diagnosis. At Kakeru Koumuten Co., Ltd., we conduct a free on-site survey to confirm the items below, compile a deterioration diagnosis report with photos, and propose the scope of work.

Reasons Kakeru Koumuten is Chosen for Large-Scale Renovations in Kohoku Ward, Yokohama

The reason why we can be entrusted with large-scale renovations in Kohoku Ward is partly because “Kakeru Koumuten has a base in Yokohama City”, but also due to our “unique initiatives in large-scale renovation work that cannot be imitated by other companies”, which have received high praise from many customers.

1. Equipment Specialized for Exterior Renovations

At Kakeru Koumuten, we have prepared the following warehouses and material storage areas to provide low-cost, high-quality exterior wall painting and waterproofing work for large-scale renovations. We have established five bases centered around Yokohama City for material storage and showrooms.

In-house Ownership of Scaffolding Materials

We own the scaffolding materials necessary for temporary scaffolding required for large-scale renovations and can assemble the scaffolding ourselves.
By performing scaffolding work with our own scaffolding team instead of outsourcing, we can cut costs on scaffolding work and provide quick and flexible responses.
We have approximately enough scaffolding materials for 100 single-family homes!

Storage of Materials in Our Large In-house Warehouse

We store paints and substrate repair materials used for exterior renovations. By ordering a large quantity of materials at once, we can procure materials at a lower cost! Additionally, we always have stock available, allowing us to provide swift responses in emergencies!

In-house Sorting of Waste Materials

In large-scale renovations, various waste materials such as leftover paint, metal, and wood are generated. At Kakeru Koumuten, we sort and recycle waste materials in-house, which helps reduce waste disposal costs.

Showroom Dedicated to Exterior Renovations

In the showroom, you can not only have meetings but also check actual samples and colors of exterior materials. You can also perform color simulations for exterior wall painting and check thermal insulation properties using a thermal insulation testing machine!

2. Cost Reduction through In-House Management and Construction

One of Kakeru Koumuten’s major strengths is in-house management and construction.

By managing everything from inquiries to project completion in a unified system, we can keep costs down while ensuring high-quality large-scale repairs. Additionally, one representative will handle everything from the estimate to project completion. Since the person in charge does not change, communication can be smooth.

We can handle everything from temporary scaffolding installation to exterior wall painting, substrate repairs, waterproofing work, and tile repairs with complete in-house construction! Those with specialized knowledge and experience will conduct inspections and actual construction for each process!

3. Obtaining Various Permits and Skilled Workers

We have obtained construction industry licenses and permits for industrial waste collection and transportation! We also have national licensed sheet metal and painting craftsmen on staff, and we are confident in our construction techniques. We can also handle large-scale roofing work for factories! We have qualified personnel for asbestos work supervisors and building materials containing asbestos investigators, so we can handle and conduct preliminary surveys for roofing materials containing asbestos.

4. Warranty and Aftercare

Most large-scale repair works, including “painting work,” “substrate repair work,” and “waterproofing work,” come with a warranty!
Aftercare maintenance is available annually, and we send out notification DM every year.

5. Flexible and Prompt Response

Our company is equipped to handle various troubles and situations related to apartments and condominiums.

We can also address exterior walls and rooftops that cannot be checked from high places using drones! During leak investigations, we can use a thermal imaging camera to help identify the cause of leaks!

We will respond according to your wishes. We also accept emergency measures for sudden leaks! We will promptly respond to urgent requests and emergencies!

6. Staff Development

Our staff create various models for skill enhancement and conduct practical training. Since different sites require various processing and techniques, we regularly provide technical training to ensure each staff member can respond effectively. We also educate on points to be careful about and areas to check during each stage of large-scale repair work.

7. Consideration for Residents and Neighbors

During large-scale repair work, we will not only notify residents and greet nearby residents, but we will also install a notice board at the entrance to display the construction schedule and announcements! Additionally, we will thoroughly educate visitors on proper manners to minimize any inconvenience to residents and neighbors.

8. Strict Quality Control

Each process will be inspected by a responsible person, and detailed construction photos will be taken. We use film thickness inspection machines and check sheets to ensure that there are no oversights in the inspections. During exterior wall painting and waterproofing work, we check the number of used paint cans to confirm that the specified amount of paint is being used, and we order paint in-house to prevent construction defects. Of course, we will also take photos of the used paint and report them.

9. Exterior Wall Painting Color Simulation

9-1 Self Color Simulation

The simulations we create can be done using actual photos of your apartment or building!You can also perform the simulation on your smartphone or computer. By simulating and then changing to a two-tone color or making an image change, we hope to enhance the stylish appearance and contribute to an increase in occupancy rates! Of course, we can also arrange paint samples for actual color confirmation.

* In Kohoku Ward, there is a scenic area (Hiyoshi), and permission is required to change the exterior wall colors within this area. There are also areas with building agreements and district plans. Having a color simulation screen will help facilitate explanations at the management association meetings and community meetings.

9-2 Confirm the Actual Color with a Test Paint!

You can order samples of the paint you are considering and conduct a test paint on your exterior wall. By doing a test paint, you can confirm the actual color and gloss!

9-3 Exterior Renovation Simulation

Exterior simulations for apartments and condominiums are also possible!
・Exterior wall color simulation (two-tone colors are also possible)
・Simulation for applying metal siding
・Simulation using accent materials such as cornices and louvers
・Simulation for roof painting and roof replacement work

With the exterior renovation simulation, you can significantly reduce the risk of failure in image change! We hope that renovating the appearance of your apartment or condominium will help increase occupancy rates.

Cost Estimates for Major Repairs in Kohoku Ward, Yokohama

The cost of major repairs varies significantly depending on the size of the building, its deterioration status, the scope of work, and the materials used. First, refer to the national average based on public statistics, then to our company’s cost estimates based on our construction records, and finally to examples of unit prices for each project.

The national average for condominiums is 750,000 to 1,500,000 yen per unit

According to a survey conducted by the Ministry of Land, Infrastructure, Transport and Tourism, which compiled 818 construction cases (FY 2021), approximately 70% of the costs for major repairs are concentrated between 750,000 and 1,500,000 yen per unit, with the most common price range being 1,000,000 to 1,250,000 yen. The city of Yokohama also indicates on its official website that the cost is approximately 1,000,000 to 1,300,000 yen per unit. Note that the amounts in this survey do not include consumption tax and common temporary construction costs, so they differ from the current total construction costs including tax.

Source: Ministry of Land, Infrastructure, Transport and Tourism “Survey on Large-Scale Renovation Work for Condominiums in FY2021” (200 companies, 818 cases) / Yokohama City “Market Prices for Large-Scale Renovation Costs and How to Address Shortfalls in Repair Reserves” *Amounts do not include consumption tax or common temporary construction costs. Percentages may not total 100% due to rounding and non-responses.

Breakdown of Construction Costs (What the Money is Spent On)

Source: Ministry of Land, Infrastructure, Transport and Tourism “Survey on Large-Scale Renovation Work for Condominiums in FY2021” (Second survey of large-scale renovation work. Overall average is construction-related 59.0%, temporary construction 22.3%, miscellaneous expenses 9.9%). *The total does not equal 100% because it includes equipment-related work, exterior works, and others. This is an average value and is not a criterion for judging the appropriateness of individual estimates.

Cost Estimates by Building Size (Scaffolding, Substrate Repair, Exterior Painting, Waterproofing, Sealing)

*The above estimates are based on Kakeru Koumuten’s construction records and may vary depending on the presence of roofing work, metal work, plumbing, etc. For apartments, please also consider the national statistics above (750,000 – 1,500,000 JPY per unit) multiplied by the number of units as a reference.

Breakdown of Costs for Temporary Works, Substrate Repair, Exterior Walls, and Waterproofing

The estimate for large-scale repairs is broadly divided into “Temporary Works,” “Substrate Repair,” “Sealing,” “Exterior Painting,” “Waterproofing,” and “Miscellaneous Expenses.” Before comparing total amounts, please check what each item includes, how much, and at what cost.

Unit Price Examples for Repair Work

*Costs and warranty periods vary depending on shape, quantity, substrate condition, and type of materials. If you would like a detailed estimate, please feel free to contact us. Estimates are completely free.

Select Paint and Waterproofing Grades Based on “Years Until Next Repair”

“Good paint does not equal the right choice.” The best way to choose is to align when you will do the next major repair with the lifespan of the materials to avoid waste.

*The estimated lifespan is a general guideline and may vary depending on sunlight, location, and substrate condition. For areas exposed to strong rain and sunlight, choosing high-weather-resistant paint and specifications that include rust prevention for metal parts after cleaning will change durability.

Guidelines for Repair Reserve Funds and Options When Insufficient

The Ministry of Land, Infrastructure, Transport and Tourism guidelines indicate the estimated repair reserve fund on a monthly basis per exclusive area. Additional charges are necessary if there is a mechanical parking lot.

Source: Ministry of Land, Infrastructure, Transport and Tourism “Guidelines for Repair Reserve Funds for Condominiums” (Reiwa 6 June Revision – PDF) / National average is 13,378 JPY per unit per month (Reiwa 5 Fiscal Year Comprehensive Survey of Condominiums)

In the Reiwa 5 Fiscal Year Comprehensive Survey of Condominiums, 36.6% of management associations responded that “the repair reserve fund is insufficient compared to the plan.” There are four main options when there is a shortfall.

Subsidies, Tax Systems, and Loans to Check for Large-Scale Renovations in Kohoku Ward, Yokohama

Both Yokohama City and Kanagawa Prefecture do not have subsidies specifically for large-scale renovation work. The available options can be broadly categorized into the following four types. The eligibility and application status of these systems may change during the fiscal year, so be sure to confirm with our company or the respective offices before contracting or starting work. (As of October 8, 2026)

① Condominium Longevity Promotion Tax System (Reduction of Fixed Property Tax)

If large-scale repairs (including exterior painting, floor waterproofing, and roof waterproofing) that contribute to the longevity of certain qualifying condominiums are carried out, the fixed property tax amount for the following year will be reduced by half (up to the equivalent of 100㎡ per unit; urban planning tax is not included).

② Support for Apartment Management in Yokohama City (Management Associations Start Here)

The support system in Yokohama City is mostly based on registration in the “Yokohama City Apartment Registration System” (free). Management associations that are not yet registered should start here.

Source: Yokohama City “Support and Subsidy System List by Concerns for Condominium Management Associations”／Long-term Repair Plan Creation Promotion Model Project／Condominium Advisor Dispatch／Seismic Reinforcement Subsidy for Specific Buildings／Yokohama Condominium Portal

③ Management Plan Certification System (Tax and Interest Rate Benefits)

This is a system certified by Yokohama City. Upon certification, the loan interest rate from the Japan Housing Finance Agency is reduced by 0.2% per year, preferential interest rates for Flat 35, and it meets one of the requirements for the long-life promotion tax system (certification alone does not guarantee tax reduction). The main criteria include holding general meetings at least once a year, improving management regulations, separate accounting for management fees and repair reserves, overdue amounts within 10% of the total, and “having created or reviewed a long-term repair plan that includes large-scale repair work twice or more within 30 years and within 7 years”, among others.

*Fees include a system usage fee of 10,000 yen + city application fee of 3,900 yen, etc. It takes 2 to 3 months from application to certification. The certification is valid for 5 years.

④ National Energy Conservation Support | Housing Energy Conservation 2026 Campaign

Changes for FY 2026The “Child-rearing Green Housing Support Project” for FY 2025 has been abolished and reorganized into the successor “Mirai Eco Housing 2026 Project.” Additionally, the “Long-term Excellent Housing Renovation Promotion Project” will end in FY 2027 and will not be implemented in FY 2028. Please be careful not to establish financial plans based on outdated information.

Mirai Eco Housing 2026 Project

Advanced Window Renovation 2026 Project

⑤ Kanagawa Prefecture Subsidies (Applications for Fiscal 2026 have ended)

* The Existing Housing Energy Efficiency Renovation Subsidy does not cover common areas of rental apartments or units not occupied by the owner.

⑥ Financing System (Housing Finance Agency Condominium Sumairu Loan)

If the management association borrows funds for large-scale repairs, the Housing Finance Agency’s “Condominium Common Area Renovation Loan (Condominium Sumairu Loan)” can be utilized.

Source: Housing Finance Agency “Condominium Sumairu Loan” (Official)

Cases where fire insurance can be used and cases where it should not be used

Building conditions and repair points in Kohoku Ward, Yokohama City

Kohoku Ward, Yokohama City, is located in the northeastern part of Yokohama City and borders Kawasaki City to the north and northeast. It is situated at the eastern edge of the Tama Hills, consisting of gentle hills and flatlands that open up along the Tsurumi River and Hayabuchi River, which meander through the hills. The area has expanded over time with the opening of the Tokyu Toyoko Line in 1926 and the establishment of Kikuna Station, followed by the opening of the Tōkaidō Shinkansen and Shin-Yokohama Station in 1964. The presence of different areas within the same ward, such as the urban area in front of the Toyoko Line stations, Shin-Yokohama with a Shinkansen station, flatlands along the Tsurumi River, and residential areas spreading across the hills, serves as a starting point for considering large-scale repairs in Kohoku Ward.

Source: Yokohama City “Estimated Population and Household Numbers” (Population News) / Kohoku Ward “Basic Statistics” / Kohoku Ward “Location and Topography” / Kohoku Ward “Overview of History” / Yokohama City “District Plan (Kohoku Ward)” / Yokohama City “List of Scenic Areas”

Let’s also check the overall numbers for housing in the ward. The homeownership rate in Kohoku Ward is 48.5% (Reiwa 5 Housing and Land Statistical Survey). Since households living in rental apartments and condominiums exceed half of the total, establishing a communication system among owners, management companies, and tenants is crucial for advancing large-scale repairs. Please note that these figures represent the entire ward and do not indicate the condition of individual buildings.

Kohoku Ward Buildings are Divided into “Four Faces”

The buildings in Kohoku Ward reflect the history of urban expansion, which has resulted in distinct characteristics for each location. The nature of the major repairs required for your building will vary depending on its location. Additionally, since the history of reconstruction and large-scale renovations differs from building to building, please consider the age of the building as a guideline.

Source: Kohoku Ward “Overview of History” (Opening of the Toyoko Line and the opening of Kikuna Station in 1926, Tsunashima Onsen Bathhouse in 1927, relocation of Keio University Pre-college to Hiyoshi in 1934, opening of Shin-Yokohama Station in 1964, opening of the subway in Shin-Yokohama in 1985, subdivision of Tsuzuki Ward in 1994) / Yokohama City “Building Agreement (Kohoku Ward)” / Yokohama City “District Plan (Kohoku Ward)” / Yokohama City “Flood Hazard Map”

Four Factors Unique to Kohoku Ward That Damage Buildings

The contents of large-scale repairs vary depending on the location of the building. When investigating buildings in Kohoku Ward, we particularly check the following four factors. While I will discuss based on the overall trends in the ward, the actual conditions differ from building to building, so we will always confirm on-site.

Source: Kohoku Ward “Location and Topography” / Yokohama City “Flood Hazard Map”・Yokohama City Public Relations Kohoku Ward Edition (2023) / Ministry of Land, Infrastructure, Transport and Tourism Keihin River Office “Tsurumi River Maintenance” / Yokohama City “List of Scenic Districts” / “Permits in Scenic Districts” / “Building Agreements (Kohoku Ward)”

Key Points to Consider When Advancing Construction in Kohoku Ward

*Kakeru Koumuten has five locations in Yokohama City, including showrooms and material storage, and we respond to inquiries throughout Kohoku Ward, including Kikuna, Tsunashima, Okurayama, Hiyoshi, Shin-Yokohama, Kozukue, and Shin-Hane.

Signs of Deterioration Requiring Major Repairs and Timing

Generally, major repairs are considered to be on a 12 to 15-year cycle. According to the Ministry of Land, Infrastructure, Transport and Tourism’s actual survey, the actual repair cycle is most commonly 13 years, with about 70% falling within the 12 to 15-year range, and the cycle tends to shorten with each occurrence. However, the actual judgment should be based on the condition of deterioration rather than the number of years, so if you observe symptoms like those below, we recommend an early on-site investigation.

Repair Cycle Guidelines by Part (Ministry of Land, Infrastructure, Transport and Tourism Guidelines)

*The above are reference examples from the guidelines and are not uniform construction deadlines. Actual cycles will be set according to the specifications, location conditions, and deterioration status of the building.

Source: Ministry of Land, Infrastructure, Transport and Tourism “Long-Term Repair Plan Creation Guidelines” (Revised June 2024, PDF) / Ministry of Land, Infrastructure, Transport and Tourism “Fiscal Year 2021 Survey on Large-Scale Repair Work for Condominiums”

Examples of Large-Scale Renovation Work

This is an example of exterior renovation work on a mixed-use building undertaken by Kakeru Koumuten. The building had leaks occurring in several places, and we combined clear waterproofing for the tile exterior wall with waterproofing for the rooftop for the renovation.

Exterior Renovation Work on a Mixed-Use Building (Tile Exterior Wall Waterproofing + Rooftop Waterproofing)

Customer Feedback

Flow from On-Site Survey to Completion of Construction

From inquiry to completion of construction and aftercare, one representative will consistently handle your case. In the case of management associations, a resolution at the general meeting is necessary, so starting the process 1 to 1.5 years before the desired start date will allow for a smoother progression.

1. Contact Us (Free) Please reach out via phone, form, or LINE. If you have estimates from other companies, it’s fine to just present those.
2. On-Site Investigation & Building Diagnosis (Free) We will conduct a survey of the exterior walls, check for cracks, sealing, and waterproof layers, and if necessary, investigate the rooftop, high places, and leak areas using drones or thermal imaging. For properties in Kohoku Ward, we will also check for rust on iron parts, the possibility of flooding on the premises, the condition of slopes and retaining walls, as well as the delivery route and parking.
3. Investigation Report & Estimate Submission We will provide a deterioration diagnosis report with photos and an estimate detailing quantities, methods, and materials for each work item. Multiple plans can also be proposed.
4. Plan Decision & Contract Confirm colors through color simulations, sample boards, and trial painting. For management associations, we can assist in preparing materials for general meetings. In areas subject to scenic district regulations, district plans, or building agreements, we will also explain the procedures and color considerations.
5. Notification to Residents & Neighbors We will distribute construction notices, visit neighbors to greet them, and set up a bulletin board at the entrance (with a schedule and laundry information). If temporary relocation of parking is necessary, adjustments will be made at this stage.
6. Temporary Scaffolding Installation & Various Works Our own scaffolding team will set up the scaffolding, followed by high-pressure washing → substrate repair → sealing → exterior wall painting & tile repair → waterproofing → iron and ancillary parts in that order. A supervisor will inspect each process and take construction photos.
7. Completion Inspection, Scaffolding Dismantling & Handover We will confirm the finish in the presence of the customer and provide construction photos, a report on the paints used, and a warranty.
8. Aftercare Maintenance We will send annual DM notifications, and inspections can be conducted every year. Simple repairs such as partial sealing are provided free of charge.

Resident Communication, Additional Work Approval & Inspection Reports

Just as important as the construction itself is “when, what, and with what materials we report”. At Kakeru Koumuten, we will provide materials and reports in the following four situations.

* For management associations, it is smooth to decide in advance who will approve additional work (such as the chairman or repair committee) and the estimated amount that requires approval before the contract.

How Will Life Be During Construction? Impact on Residents

For large-scale repairs, the principle is to proceed while you continue to live in your home. However, there will be some restrictions on daily life while scaffolding is in place. Most troubles can be prevented by providing prior notice, so Kakeru Koumuten Co., Ltd. thoroughly explains and posts information before the work begins.

How to Choose a Large-Scale Repair Contractor and Ordering Method

There are many large-scale repair contractors that cover Kohoku Ward in Yokohama City, and you may be unsure which contractor to choose. When requesting renovations for apartments, condominiums, or buildings, please check the following four points.

Have Extensive Experience in Large-Scale Repairs

Large-scale repair contractors often have websites that showcase their exterior renovation achievements. If they provide detailed explanations of repair contents with photos, it gives you peace of mind as a reference when you actually request work.

Using Google and review sites to evaluate large-scale repair contractors can also be effective when comparing them! Be cautious if there are many negative reviews. If there are few reviews, also check their construction achievements, explanation content, and management system.

Large-scale repair work involves not only the construction itself but also the potential for troubles with residents and nearby neighbors. Therefore, it is necessary to post updates on the progress of the work and information about laundry on bulletin boards to prevent issues before they arise. Kakeru Koumuten Co., Ltd. specializes in exterior work, and we receive many requests for exterior renovations of apartments and condominiums.

Check for Warranty and Aftercare Services

When choosing a large-scale repair company, make sure to confirm the availability of a warranty. If any issues such as leaks occur after the work is completed, having a leak warranty from the contractor ensures that repairs can be made at no cost, providing peace of mind! Companies that offer a warranty demonstrate confidence in their work, which can serve as a criterion for selecting a contractor.

Warranty periods vary by contractor and the nature of the work, but typically range from 1 to 10 years. Emergency repairs or partial fixes often do not come with a leak warranty. Some contractors also offer aftercare services separate from the warranty, so be sure to check for the availability of warranties and aftercare services.

At Kakeru Koumuten Co., Ltd., we send out annual direct mail for aftercare maintenance, allowing for yearly inspections. We also provide free support for simple repairs such as partial sealing.

Obtain Estimates from Multiple Contractors (at least 3 companies)

When requesting large-scale repairs, be sure to obtain estimates from multiple contractors. It is important to get estimates from at least 3 companies and compare their quotes and reports! Even for the same work, costs can vary between contractors, as well as warranties and aftercare services. Additionally, obtaining multiple estimates makes price negotiations easier.

When comparing estimates, consider not only the cost but also the “items in the estimate,” “methods and materials for substrate repairs and exterior wall painting,” and “confirmation of the process”. Avoid making decisions based solely on cost, as lower-quality materials or skipping steps can reduce expenses. Especially since substrate repair work can be difficult to assess visually, ensure that the repair methods are suitable for the condition of the substrate!

Check This on the Estimate (Checklist)

Check if it is managed in-house

Large-scale repair work includes various tasks such as “substrate repair work,” “exterior wall painting,” “waterproofing work,” and “pipe replacement,” and the plan content will change based on the actual deterioration condition and customer preferences.

Contractors that completely outsource to subcontractors may lack knowledge and experience, leading to proposals for repairs in irrelevant areas or meaningless work. If you investigate and then request a subcontractor, it may incur additional time and costs. By having knowledge and experience and managing in-house, responsible construction can be performed at a reduced cost.

Additionally, contractors that outsource may also be slow to respond in case of any troubles during construction. It is safer to avoid having a company that has not actually met with the customer manage the construction. Kakeru Koumuten performs everything from temporary scaffolding setup to exterior wall painting and waterproofing work in-house, managed by knowledgeable and experienced personnel!

There are three ordering methods. The choice affects the approach.

Especially for management associations, it is necessary to decide “how to request” before “which company to hire.” The main ordering methods are the following three.

Collusion and Inappropriate Consulting Issues in Large-Scale Renovations and Self-Defense Measures

Latest 2026 In the large-scale renovation industry, inappropriate orders linked between design consultants and construction companies have long been a problem. The Ministry of Land, Infrastructure, Transport and Tourism issued warnings and notifications to management associations in January 2017 and April 2023, and on September 28, 2026, the Japan Fair Trade Commission announced that it had issued exclusion orders to 38 companies and imposed a total of 1.63788 billion yen in surcharge payment orders to 37 companies regarding large-scale renovation work commissioned by condominium management associations to design consulting firms in the Kanto region (two design consulting firms were also subject to exclusion orders).

※Based on the announcement by the Japan Fair Trade Commission (September 28, 2026).

Three Typical Methods

Source: Yokohama City “What is collusion in large-scale repair work for condominiums?” / Ministry of Land, Infrastructure, Transport and Tourism “On the Proper Ordering of Large-Scale Repair Work for Condominiums” (Notification dated April 3, 2023, PDF)

Self-Defense Measures for Management Associations

• Obtain independent estimates from multiple companies
• Consult with neutral third parties such as condominium management professionals or architects
• Document the vendor selection process in meeting minutes to ensure transparency
• Confirm the reasons for unusually low consulting fees
• Include a penalty clause in the contract for cases of collusion
• Avoid concentrating information with a single consultant and verify specifications independently

New System in Yokohama City Bid Agency Service for Large-Scale Repair Work

In response to this issue, in October 2025, Yokohama City and the Yokohama City Housing Supply Corporation established the “Bid Agency Service for Large-Scale Repair Work.” This system separates the selection of design and construction companies, with the corporation acting as a third party to conduct conditional public competitive bidding. The estimated price will not be disclosed and will be conducted in accordance with public works methods.

Source: Yokohama City Press Release (October 16, 2025) / Yokohama City Housing Supply Corporation

Frequently Asked Questions about Large-Scale Repairs in Kohoku Ward, Yokohama

How much does large-scale repair in Kohoku Ward, Yokohama cost?

For condominiums, according to the Ministry of Land, Infrastructure, Transport and Tourism’s survey for the fiscal year 2021, about 70% of cases fall within the range of 750,000 to 1,500,000 yen (excluding consumption tax and common temporary costs), with the most common range being 1,000,000 to 1,250,000 yen. Yokohama City also indicates “approximately 1,000,000 to 1,300,000 yen per unit.” Based on our construction records, the cost for a two-story wooden apartment is estimated at 2,000,000 to 4,000,000 yen, for a three-story steel or RC apartment at 4,000,000 to 9,000,000 yen, and for small condominiums or mixed-use buildings at 5,000,000 to 15,000,000 yen. The cost varies depending on the condition of the substrate and whether waterproofing and roofing work is required, so we provide free on-site estimates.

How often should large-scale repairs be conducted?

Generally, a cycle of 12 to 15 years is recommended, and the actual cycle is most commonly 13 years according to the Ministry of Land, Infrastructure, Transport and Tourism’s survey, with about 70% falling within 12 to 15 years. However, the decision should be based on the condition of deterioration rather than just the number of years. If deterioration of sealing, tile lifting, or breaks in the waterproof layer are observed, it is better to repair without waiting for the cycle, as this can ultimately reduce costs. For older buildings, the proportion of tile repairs and iron part replacements tends to increase in the second and third rounds of repairs.

How long does the construction period take? Can residents stay during the work?

For apartments, the duration is approximately 3 weeks to 2 months; for small condominiums or buildings, it is about 1.5 to 3 months; and for condominiums with more than 50 units, it typically takes 4 to 6 months. Residents can remain in their homes during the construction. However, while scaffolding is in place, there may be restrictions on drying laundry outside and opening windows, so we take thorough measures to minimize the impact on daily life, including distributing advance notices, providing information on the schedule and laundry on bulletin boards, and strictly adhering to working hours.

How long should I expect from the start of planning to the completion of construction?

For management associations, it typically takes about 1 to 1.5 years for establishing the repair committee, conducting building diagnostics, selecting contractors, and passing resolutions at general meetings, followed by 3 to 6 months for construction. Overall, it is advisable to plan for about 2 years to proceed comfortably. If using subsidies or tax incentives, please also factor in the time to obtain management plan certification (2 to 3 months from application to certification).

Are there any subsidies available for large-scale repairs in Kohoku Ward, Yokohama?

Neither Yokohama City nor Kanagawa Prefecture offers subsidies specifically for large-scale repair work. However, for condominium owners, if certain conditions are met, there are reductions in fixed property tax by half under the “Condominium Longevity Promotion Tax System,” subsidies from Yokohama City for deterioration diagnosis and long-term repair planning (half, up to 200,000 yen), and subsidies for barrier-free modifications in common areas (one-third, up to 300,000 yen). If the work includes windows and insulation, it may qualify for “Advanced Window Renovation 2026” or “Mirai Eco Housing 2026.” The application timing and applicants differ by program, so please check the eligibility conditions and application procedures for each program before contracting or starting construction.

I heard that fixed property tax can be reduced with large-scale repairs; is that true?

Yes, it is true if the conditions are met. Under the Condominium Longevity Promotion Tax System, if a condominium that meets the requirements (20 years or older, with more than 10 units) conducts large-scale repairs that contribute to longevity (including exterior wall painting, floor waterproofing, and roof waterproofing), the fixed property tax for the following year can be reduced by half for up to 100 square meters per unit. This applies to work completed between April 1, 2023, and March 31, 2027, and a declaration must be made to the Kohoku Ward Office within three months of completion. For certified management plan condominiums, there are additional requirements such as raising the repair reserve fund, so it is recommended to start preparations more than a year before construction.

Are there any changes to subsidies starting from the fiscal year 2026?

Yes, there are. The national “Child-Rearing Green Housing Support Project” has been abolished and reorganized into the successor “Mirai Eco Housing 2026 Project.” Management associations and management corporations can also become joint project participants, allowing for insulation renovations in common areas. Additionally, the “Long-Term Excellent Housing Renovation Promotion Project” will end in fiscal year 2025, and it will not be implemented in fiscal year 2026. The “Advanced Window Renovation 2026 Project” has begun accepting bulk applications for apartment buildings starting May 29, 2026 (the application process is handled by registered contractors). Please be careful not to base your financial plans on outdated information.

What should I do if the repair reserve fund is insufficient?

There are mainly four options: ① Postpone low-urgency work based on deterioration diagnosis to the next time, ② Review the scope and specifications of the work, ③ Check support systems such as subsidies, ④ Consider increasing repair reserves or financing from the Japan Housing Finance Agency. The agency’s condominium common area renovation financing does not require collateral, and interest rates can be reduced by up to 0.6% per year by obtaining management plan certification and implementing energy-saving and seismic work. Please note that postponing waterproofing and tile peeling measures often ends up being more expensive, so please consult us for a decision on separation.

Can scaffolding be set up on buildings located on sloped or uneven terrain, such as on top of retaining walls or on sloped land?

Yes, it can. Kohoku Ward is located at the eastern edge of the Tama Hills, consisting of gently rolling hills and flat land. There are buildings on sloped and terraced sites in the hillside complexes and residential areas. Kakeru Koumuten Co., Ltd. owns its own scaffolding materials and has its own scaffolding team, allowing us to plan support for the base plates and layout after confirming the site. This is an area where additional costs can easily arise after seeing the site, so it is important to confirm the delivery route during the estimation stage. We also check the deterioration of retaining walls and slopes and consult on whether they are included in the long-term repair plan.

What will happen to the parking spaces for residents during construction?

Vehicles on the side where scaffolding will be erected will need to be temporarily moved. In buildings with group or on-site parking, it may take time to secure a relocation spot depending on the number and arrangement of vehicles. Kakeru Koumuten Co., Ltd. will coordinate with you, including checking the availability of nearby coin parking and monthly parking lots, starting 2 to 3 months before construction begins.

Can I freely decide the color of the exterior walls?

This depends on the regulations affecting the property. Kohoku Ward has the Yokohama City scenic area “Hiyoshi,” where permission is required for changes to the exterior color. Additionally, there are six district plans within the ward, and multiple building agreements are established in various areas, with different contents for each district (some agreements do not specify colors). You can check what regulations apply to your property at the Yokohama City scenic area office or the building agreement office. Our company will also investigate this during the survey, share a color simulation for the completed image, and assist in forming consensus with the management association and neighbors.

Kohoku Ward is far from the sea, but are there any concerns regarding damage to exterior walls and metal parts?

Kohoku Ward is an inland ward not facing the sea, so salt damage from sea breezes is not a major concern. However, in flat areas along the Tsurumi River and Hayabuchi River, where flooding is anticipated, the waterproofing of the first floor, basement, and mechanical rooms, as well as the condition around external piping and electrical equipment, are important considerations. Flooding expectations vary by site, so you can check the Yokohama City flooding hazard map (Kohoku Ward version). Damage to exterior walls and metal parts can progress due to rainwater, sunlight, and age, so we will check the extent of rust on metal parts, sealing, and the condition of the waterproof layer during the on-site survey and specify the necessary scope in the estimate.

Which should I choose, the responsibility construction method or the design management method?

For buildings with fewer units, the burden of consulting fees tends to be heavier, so we believe that the responsibility construction method is often more suitable for small to medium-sized buildings. The design management method allows for comparison of construction companies under the same conditions since a third party creates the specifications, but it incurs separate consulting fees and requires caution regarding conflicts of interest and collusion risks. Even with the responsibility construction method, it is essential to verify price, specifications, and construction status. Kakeru Koumuten Co., Ltd. provides estimates that specify quantities, methods, and materials for each construction item, allowing you to compare with other companies on the same level.

How can I detect collusion in large-scale repairs?

There are three typical methods: ① Pre-selecting the contractor and having other companies submit only formal high estimates, known as “dummy estimates,” ② A consultant contracts at an extremely low design management fee and receives kickbacks from affiliated contractors, ③ Adding a portion of the contract amount as a back margin to the construction cost. Countermeasures include obtaining independent estimates, consulting with neutral third parties, documenting the selection process in meeting minutes, and including penalty clauses in contracts. In October 2025, Yokohama City and the Yokohama City Housing Supply Corporation will establish a “Large-Scale Repair Work Bidding Agency Service.”

How many companies should I get estimates from?

We recommend at least three companies. Too many can make comparisons difficult, while too few can reduce competition. What’s important is not the number of companies but “comparing after creating the same conditions.” By creating a common specification sheet and quantity table and requesting under the same conditions, and making detailed breakdowns mandatory instead of allowing “one set” notation, the differences in amounts can be clearly identified as differences in scope or unit prices.

What is the difference if you own your own scaffolding?

Approximately 20% of the costs for large-scale repair work consist of temporary construction (according to the Ministry of Land, Infrastructure, Transport and Tourism’s fiscal year 2021 survey). By not outsourcing scaffolding work, we can easily keep costs down in this area, and our in-house scaffolding team can flexibly respond to sudden changes or additional work. Kakeru Koumuten Co., Ltd. owns scaffolding materials for about 100 single-family homes and plans according to the site, even on slopes or uneven terrain.

I’m in the middle of comparing estimates, but can I just have a look at your estimate?

Of course, that’s possible. If you bring in estimates from other companies, we will check for free whether the items, quantities, methods, and materials are appropriate and provide you with an estimate under the same conditions. We welcome comparative estimates.

Can I request just emergency repairs for a leak?

Yes. As a preliminary step before large-scale repairs, we also accept requests for emergency repairs or partial repairs for leaks. We will identify the cause using thermal imaging and drones and propose the minimum necessary repairs.

Can you handle roofing or exterior materials that contain asbestos?

Yes, we can. We have qualified personnel, including asbestos work supervisors and building material inspectors, who can handle everything from the legally required preliminary surveys to the cover method and removal of asbestos-containing roofing materials. If there is sprayed asbestos, you may be eligible for free surveys and subsidies covering two-thirds of the removal costs (up to 3 million yen) through Yokohama City’s countermeasures project, and we will provide guidance on this as well.

What happens if I don’t carry out large-scale repairs?

There are risks such as personal injury from falling exterior tiles, structural deterioration due to corrosion of rebar, leaks, and a decrease in asset value. Furthermore, for buildings subject to regular reporting under Article 12 of the Building Standards Act, investigations through full probing are required under certain conditions, such as when more than 10 years have passed since completion or exterior wall renovations for tile or mortar-finished walls. In Yokohama City, buildings that are only apartments are not designated for regular reporting, but mixed-use buildings that include stores require individual confirmation. Even if not subject to statutory investigations, regular inspections and maintenance are essential, so please consult us if you are unsure.

How much does large-scale repair for an apartment (about 10 units) cost?

For a two-story wooden building with 6 to 10 units, the estimate is between 2 million and 4 million yen, and for a three-story steel or RC building with 10 to 20 units, it is between 4 million and 9 million yen, based on our company’s track record (including scaffolding, substrate repairs, exterior wall painting, sealing, and waterproofing). It is common to carry out repairs for apartments every 10 to 15 years. For owners, there is an increasing trend to change the appearance with color simulations during repairs to improve occupancy rates.

If you are looking for a large-scale repair contractor in Kohoku Ward, Yokohama, contact Kakeru Koumuten Co., Ltd.

We handle many exterior wall renovations and large-scale repairs for condominiums and apartments in Kohoku Ward, Yokohama. We are happy to assist not only with large-scale repair work but also with partial repairs and leak repairs. “I want it to last long with one renovation”, “I want to keep costs down as much as possible”, “I want to improve insulation performance because the indoors are hot”, we will propose the best solutions for your specific requests and future repair plans.

From temporary scaffolding work to roofing and exterior painting, all work is performed by our own team. We are confident that we will not be outdone by others in terms of cost, quality, and planning, so we welcome comparative estimates!

Areas Covered for Large-Scale Repair Work

Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and Tokyo.

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