If you are looking for a waterproofing contractor in
Kakeru Koumuten is the place to go
Kakeru Koumuten specializes in exterior renovations.
We receive many requests for waterproofing work in Aoba-ku, Yokohama, from single-family homes to apartment buildings.
“Reasons why Kakeru Koumuten is chosen in Aoba-ku”
“About the costs of waterproofing work”“
“How to choose a waterproofing contractor”
“About grants and subsidies available for waterproofing work in Aoba-ku”
We will explain the above four points!
This will definitely be useful for customers considering waterproofing work in Aoba-ku, Yokohama, so
please take a look!
Reasons why Kakeru Koumuten is chosen for waterproofing work in Aoba-ku, Yokohama
Regarding why our company is entrusted with waterproofing work by customers in Aoba-ku, Yokohama,
“Our strengths in waterproofing work that cannot be imitated by other companies”
have received high praise from many customers.
We have absolute confidence in “cost,” “quality,” and “plans,” so
we would appreciate it if you could compare our estimates with those of other companies.
Because we are confident, we welcome competitive estimates!
1.Facilities Specialized in Exterior Renovation
Kakeru Koumuten Co., Ltd. has prepared the following warehouses and material storage areas to provide more affordable and faster waterproofing and other exterior renovation services.
We have established five bases centered around Aoba-ku, Yokohama for material storage and showrooms.
In-house Scaffolding Materials


We own the scaffolding materials necessary for temporary scaffolding required for waterproofing work, allowing us to assemble temporary scaffolding in-house.
By conducting scaffolding work with our own scaffolding team instead of outsourcing, we can also reduce the costs associated with scaffolding work.
Since all work is performed in-house, it is possible to significantly reduce costs by shortening the construction period!
We have enough scaffolding materials for approximately 50 detached houses!
Storage of materials in our large in-house warehouse

We store roofing materials and waterproofing components.
By ordering a large quantity of materials at once, we can purchase materials at a lower cost!
Additionally, we always have waterproofing components in stock, allowing us to respond quickly to emergency waterproofing work!
In-house separation of waste materials
In waterproofing work, various waste materials are generated.
Most contractors dispose of them all together, but by sorting and recycling waste materials, significant cost savings on waste disposal can be achieved.
Exterior Renovation Dedicated Showroom


In our showroom, not only can you have meetings, but you can also directly check the actual structures and colors available.
2.Complete In-House Construction
One of Kakeru Koumuten’s great strengths is our complete in-house construction.
From inquiry to project completion, everything is handled by Kakeru Koumuten Co., Ltd., allowing us to keep costs down while providing high-quality waterproofing work.
Additionally, one representative will assist you from the estimate to the completion of the work.
Since the same person will handle sales and construction management, smooth communication is possible.
We are confident in our construction plans and costs, so we welcome competitive estimates!
3. Various Permits and Skilled Workers

We have obtained permits for construction and industrial waste collection and transportation!
We also have qualified professionals on staff, and we are confident in our construction techniques.
We are capable of handling large-scale waterproofing projects, such as those for factories!
4. Warranty and Aftercare
Waterproofing work comes with a guarantee!
Depending on the type of waterproofing work, we provide a 5 to 10-year leak guarantee.
If you have any questions about the guarantee, please click on the image above!
In the unlikely event that leaks are not resolved after the waterproofing work, we will take responsibility and address the issue!
Additionally, aftercare maintenance is available every year, and we will send you a DM notification for aftercare maintenance once a year.
During aftercare maintenance, we will check the entire waterproofing system and assess the condition of any deterioration.
5. Flexible and Prompt Response
Our company is equipped to handle various troubles and situations.
If we cannot access the rooftop for waterproofing checks, we will utilize drones to assess the condition.
During leak investigations, we can also conduct inspections using thermal imaging cameras.
We will respond according to your wishes.
We also accept emergency measures for sudden leaks!
Since our sales and construction management are not separated, one dedicated representative will handle everything from the estimate to the completion of the work!
Changing representatives frequently can lead to miscommunication regarding the details and precautions of the work, which could cause issues, so our company maintains a system where the representative remains the same.
6. Human Resource Development
To enhance our skills, we create various building models and conduct practical training.
We regularly provide technical training to ensure that all staff can handle various types of buildings.
Subsidies and Grants for Waterproofing Work in Shinjuku-ku, Tokyo
Tax Reduction for Promoting Longevity of Condominiums (Fixed Asset Tax Reduction)
Requirements for Tax Reduction for Promoting Longevity of Condominiums
Condominiums over 20 years old
Total number of units: 10 or more
Completion of longevity improvement work at least once in the past + completion of the second or subsequent work between April 1, 2023, and March 31, 2027
Certified management plan condominium or has established and reviewed a long-term repair plan with advice and guidance from the municipality
The residential floor area of the exclusive part occupies more than 50% of the total
Details of Tax Reduction
Eligible: Fixed asset tax on the building portion imposed in the year following the completion of the work.
Maximum Reduction: Up to equivalent to 100㎡ per unit
Reduction Rate: The tax amount within the above range is reduced by 1/2 (50%)
Others
If damage due to natural disasters is recognized, it may be covered by fire insurance.
In terms of waterproofing, examples of damage from natural disasters include “holes in waterproof sheets caused by flying objects or falling debris due to wind disasters.”
If you are unsure whether it is covered by fire insurance, please feel free to contact us!
About the Costs of Waterproofing Work
⇧ For construction menu | Click here for waterproofing work costs
Examples of Waterproofing Work
| Construction Details |
| Urethane Waterproofing Ventilated Cushion Method / High-Strength Urethane Type Existing Waterproofing: PVC Sheet Waterproofing |
| Materials Used |
| Waterproofing: AGC Polymer Building Materials / Saracene A (High-Strength Urethane) Ventilation Sheet: QV Sheet Ventilation Pipe: Stainless Steel Replaced with Renovation Drain |
| Price Range |
| 700,000 to 800,000 yen |
| Construction Period |
| Approximately 2 weeks |
| Completion Month |
| May 2024 |
| Inquiry Details |
| We have received the following inquiries from our customer. ・There are wrinkles and bulges in the waterproof sheet on the roof, so we are worried about leaks. ・We would like an estimate for a complete waterproof renovation, not just partial repairs or a top coat. ・We learned that urethane waterproofing has high waterproofing properties, so we would like an estimate for urethane waterproofing. ・As this is our first waterproofing project, we would like to compare estimates. |
Our Proposal
Since you expressed a desire to renovate using a long-lasting method rather than protective agents like top coats, we proposed a complete “urethane waterproofing project” for the roof.
If urethane waterproofing is applied using the adhesion method, air rising from the building can cause bulges in the waterproof layer, so we proposed the “urethane waterproofing ventilation buffer method.”
The ventilation buffer method involves applying a ventilation buffer sheet over the entire area before installing the urethane waterproofing.
By applying the ventilation buffer sheet first, the air rising from the building is suppressed by the ventilation sheet and discharged through the “ventilation pipe.”
This can prevent the most common issue with waterproofing, which is bulging of the waterproof layer!
After explaining the materials and methods, you entrusted us with the project among four competing estimates!
Timing for Waterproofing Work
Leaks Have Already Occurred
If leaks have already occurred, it is necessary to address the issue promptly before the damage spreads.
If left unattended, it can adversely affect the interior and underlying structures, so it is essential to stop the leaks quickly.
Bulges or Cracks in the Waterproof Layer
If the waterproof section is cracked, it can lead to rainwater intrusion.
If the waterproof layer is bulging, it indicates that moisture is accumulating within the layer.
Bulges can lead to cracks, which can result in leaks, so early detection and action are necessary.
Moss or Mold Growth
Moss or mold can develop due to the accumulation of moisture or rainwater.
This can be caused by poor drainage or sinking of the waterproof layer due to aging.
Exceeding the Durability Period
Generally, the durability period for waterproofing work is 10 to 20 years.
Of course, the durability period can vary depending on the construction method and materials, but for some types of waterproofing, it is recommended to apply only the surface protective agent (top coat) approximately every 8 years (such as urethane waterproofing or FRP waterproofing).
We recommend conducting regular inspections starting from 5 years after construction.
Understanding the types of waterproofing and performing appropriate maintenance is essential.
If you are unsure about the type of waterproofing, please send us a photo via email or LINE, and we will help you determine it!
Types of Waterproofing Work
1. Urethane Waterproofing
Urethane waterproofing is a method that involves applying liquid polyurethane resin to the waterproofing surface.
Since it is liquid before curing, it can be applied to complex shapes, and unlike sheet waterproofing, it can be installed without seams, which is a significant advantage. It can be widely applied to balconies, rooftops, and more.
For more detailed information on the advantages, disadvantages, and maintenance methods of urethane waterproofing, please refer to the article below.
For more on waterproofing work | Urethane waterproofing, click here!
2. Rubber Sheet Waterproofing
Rubber sheet waterproofing involves adhering synthetic rubber sheets to the surface to prevent water intrusion.
This type of waterproofing is often used for large areas, such as rooftops.
Compared to urethane waterproofing, it has the advantage of faster installation since there is no waiting for drying, but it is not suitable for complex surfaces.
For more detailed information on the advantages, disadvantages, and maintenance methods of rubber sheet waterproofing, please refer to the article below.
For more on waterproofing work | Rubber sheet waterproofing, click here!
3. PVC Sheet Waterproofing
PVC sheet waterproofing is a waterproof sheet made of polyvinyl chloride, which, like rubber sheet waterproofing, is applied to the surface to prevent water intrusion.
Similar to rubber sheets, it is not suitable for complex shapes. Although the cost is higher than rubber sheets and urethane waterproofing, its long durability is a significant advantage.
For more details on the advantages and disadvantages of PVC sheet waterproofing and maintenance methods, please refer to the article below.
Waterproofing Work | Learn more about PVC Sheet Waterproofing here!
4. Long Sheet Waterproofing
Long sheet waterproofing, officially known as “slip-resistant vinyl flooring sheet,” is commonly applied in shared areas of apartments and stairways where people walk.
As the name suggests, it is slip-resistant and has high durability and abrasion resistance, making it suitable for walking areas.
Additionally, it comes in various designs, excelling in aesthetic appeal.
However, it tends to be more expensive, and since it does not overlap seams like rubber sheets or PVC sheets, it may give a slightly lower impression of waterproofing capability.
It is rarely used in areas such as rooftops of apartments where people do not frequently enter and exit.
For more details on the advantages and disadvantages of long sheet waterproofing and maintenance methods, please refer to the article below.
Waterproofing Work | Learn more about Long Sheet Waterproofing here!
5. FRP Waterproofing
FRP waterproofing involves creating a waterproof layer by hardening glass mat with epoxy resin to prevent rainwater intrusion.
It is commonly applied on balconies of single-family homes, with an overwhelmingly short construction period, often completed in as little as one day.
Due to its lightweight and low cost, it is estimated that about 80% of balconies in single-family homes use FRP waterproofing.
However, it is not suitable for construction on large areas, making it less appropriate for rooftops.
For more details on the advantages and disadvantages of FRP waterproofing and maintenance methods, please refer to the article below.
Waterproofing Work | Click here for FRP Waterproofing!
6. Asphalt Waterproofing
Asphalt waterproofing is a waterproof sheet that has asphalt permeated into synthetic fiber non-woven fabric.
The waterproofing shown in the photo is a method where asphalt waterproofing is pressed down with cinder concrete.
This waterproofing is used for large buildings such as rooftops of schools and commercial facilities.
There are various methods of asphalt waterproofing, each with its own advantages and disadvantages, but a major benefit is its high durability.
For more details on the advantages, disadvantages, and maintenance methods of asphalt waterproofing, please refer to the article below.
Waterproofing Work | Click here for Asphalt Waterproofing!
How to Choose a Waterproofing Contractor
There are many waterproofing contractors available in Shinjuku-ku, Tokyo.
Among the numerous contractors, I believe there are many who feel, “I don’t know who to ask for help…”
Choosing the right contractor can be challenging at first, so I will explain 5 points to consider when requesting waterproofing work.
● Have extensive experience in waterproofing work
● Confirm the presence of aftercare and warranty
● Obtain estimates from multiple contractors (at least 3 companies)
● Check if they perform waterproofing work in-house
● Carefully review the contents of the waterproofing estimate, processes, and materials used
By confirming the above 5 points, you will be able to choose a reliable contractor.
Check if they have extensive experience in waterproofing work
About 10-20% of waterproofing work troubles are caused by construction defects during the installation.
To prevent troubles, it is important to hire a contractor who is experienced and trustworthy!
You need to refer to the contractor’s website for their construction achievements and reviews to make a judgment.
There are also contractors who showcase their achievements on social media platforms like Instagram, so checking those can be effective!
It is also effective to look at waterproofing companies on review sites for reference!
The review site we particularly recommend is “Google”.
Since contractors cannot arbitrarily delete low ratings, it provides reliable reviews.
If there are many negative reviews or no reviews at all, it may be wise to refrain from making a request.
Check if there is aftercare maintenance and construction warranty
In case of any construction defects or issues after the work is completed, let’s confirm if they provide a “construction warranty“!
Contractors who offer warranties are usually confident in their work, making them more trustworthy companies!
If waterproofing work is done, make sure to take photos of hidden areas during the process for confirmation!
Check for leaks during rainy weather after the waterproofing work, and if anything arises, contact the contractor immediately as it will facilitate smooth communication shortly after the work is completed!
Additionally, to ensure early detection of any issues that may arise, confirm if they conduct thorough aftercare maintenance!
Since non-specialized contractors may not notice signs of issues or troubles, having a specialized contractor perform regular aftercare maintenance can help prevent problems before they occur!
Our company sends out aftercare maintenance DM every year, so if desired, annual aftercare maintenance is possible!
Obtain estimates from multiple contractors (at least three)
When requesting waterproofing work, always obtain estimates from multiple contractors.
We recommend obtaining estimates from at least three companies.
Even for the same waterproofing work, costs may vary between contractors, and warranties and after-services may differ as well.
Additionally, obtaining multiple estimates makes it easier to negotiate prices. To request at the lowest possible cost, it is essential to get estimates from several contractors.
When comparing estimates, be sure to check not only the costs but also the “types of materials used” and “construction methods,” and compare the finer details!
Check if they perform waterproofing work in-house
Let’s confirm whether we handle waterproofing work in-house!
If a sales company investigates and then requests a subcontractor, it can lead to extra time and costs.
Additionally, there may be instances where customer requests are not fully communicated to the subcontractor, leading to potential troubles.
By having one company handle everything from sales to construction, we can provide responsible waterproofing work that is quick and cost-effective. Kakeru Koumuten Co., Ltd. conducts everything from on-site surveys to actual construction in-house!
Moreover, in the unlikely event of a leak or trouble, a company that employs its own craftsmen can respond to and resolve issues quickly!
Carefully check the details of the waterproofing estimate, process, and materials used
Even for the same waterproofing work, there are various types such as “method,” “materials,” and “process,” and it is necessary to use the optimal method and materials based on the construction location and existing substrate.
For example, even with the same urethane waterproofing, there are different types of processes like “adhesion method” and “ventilated buffer method,” and there are various types of urethane waterproofing materials such as “high-strength specification,” “heat-insulating specification,” and “anti-slip specification.” Therefore, it is essential to confirm whether the construction content is appropriate for the location!
It is important not to judge solely based on cost, but to carefully check whether “the method is appropriate for the substrate?” and “are the materials suitable?”
So, if the materials used are only “urethane waterproofing materials,” make sure to check the product name and understand what kind of materials they are!
If you are looking for waterproofing contractors in Shinjuku-ku, Tokyo, please contact Kakeru Koumuten Co., Ltd.
Our company handles many waterproofing projects in Shinjuku-ku, Tokyo.
Our greatest strength is that we can handle everything from proposals to temporary scaffolding installation and waterproofing work in-house!
Kakeru Koumuten Co., Ltd. promises “high-quality waterproofing work at low cost”, and we have received positive feedback from many customers.
We continue to update our annual construction performance, and we will strive to improve quality to satisfy even more customers in the future.
We are happy to handle even small partial projects!
Not only waterproofing work but also roofing work, exterior painting, and exterior cover methods can all be performed in-house.
We are confident that we will not be outdone by other companies in terms of cost, quality, and organization for exterior work!
We welcome competitive estimates with confidence!
Estimates are completely free, and if our company is found to be inferior to others, you are free to decline!
For information on exterior renovations in Shinjuku-ku, Tokyo, click here!
For information on exterior painting in Shinjuku-ku, Tokyo, click here!
For information on roof renovations in Shinjuku-ku, Tokyo, click here!
For information on leak repairs in Shinjuku-ku, Tokyo, click here!
Features of Shinjuku-ku, Tokyo
Shinjuku-ku, Tokyo is located in the central part of the 23 wards of Tokyo, covering an area of approximately 18 km². Shinjuku Station is one of the world’s busiest terminal stations, with about 3.5 million passengers daily, and the surrounding area is home to large commercial facilities, hotels, restaurants, and service industries. The population of Shinjuku-ku is around 330,000, characterized by a high percentage of single-person households and elderly residents. Additionally, the daytime population is about 770,000, indicating a significant influx of commuters and students, resulting in a daytime-to-nighttime population ratio of approximately 250%. Furthermore, there are about 40,000 registered foreign residents, making it a culturally diverse area.
Shinjuku-ku features a variety of areas, including the skyscraper district of Nishi-Shinjuku, the entertainment district known as Kabukicho, the historic and charming Kagurazaka, and the bustling Koreatown of Hyakunincho. It is also home to many new industry businesses, such as IT companies, and has developed into a vibrant city where industry and culture blend.
Thus, Shinjuku-ku is an attractive area where diverse cultures and industries converge, and it is cherished by many as a hub for tourism and business.
Our company offers a wide range of waterproofing services in Shinjuku-ku. We can handle all exterior renovations, including waterproofing, roofing, and exterior painting, with our own skilled team.
If you have any concerns, please feel free to consult with us!
Waterproofing Service Areas
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and all of Tokyo.
List of Areas in Shinjuku-ku, Tokyo
Aizumicho, Shinjuku-ku / Akagishitamachi, Shinjuku-ku / Akagimotomachi, Shinjuku-ku / Agabacho, Shinjuku-ku / Arakicho, Shinjuku-ku / Ichigaya Kagawa-cho, Shinjuku-ku / Ichigaya Kōrō-cho, Shinjuku-ku / Ichigaya Satohara-cho, Shinjuku-ku / Ichigaya Sauen-cho, Shinjuku-ku / Ichigaya Takashō-cho, Shinjuku-ku / Ichigaya Tamachi, Shinjuku-ku / Ichigaya Daichō, Shinjuku-ku / Ichigaya Nagennji-cho, Shinjuku-ku / Ichigaya Nakano-cho, Shinjuku-ku / Ichigaya Hachiman-cho, Shinjuku-ku / Ichigaya Funakawara-cho, Shinjuku-ku / Ichigaya Motomura-cho, Shinjuku-ku / Ichigaya Yakuōji-cho, Shinjuku-ku / Ichigaya Yanagicho, Shinjuku-ku / Ichigaya Yamanobori-cho, Shinjuku-ku / Iwatokacho, Shinjuku-ku / Enokicho, Shinjuku-ku / Okubo, Shinjuku-ku / Kaidate-cho, Shinjuku-ku / Kagurakawagashi, Shinjuku-ku / Kagurazaka, Shinjuku-ku / Kasumigaoka-cho, Shinjuku-ku / Katamachi, Shinjuku-ku / Kabukicho, Shinjuku-ku / Kamiochiai, Shinjuku-ku / Kawadacho, Shinjuku-ku / Kikui-cho, Shinjuku-ku / Kitashinjuku, Shinjuku-ku / Kitamachi, Shinjuku-ku / Kitayamanobori-cho, Shinjuku-ku / Saikucho, Shinjuku-ku / Samon-cho, Shinjuku-ku / Shinano-cho, Shinjuku-ku / Shimoochiai, Shinjuku-ku / Shimomiya-bicho, Shinjuku-ku / Shirogane-cho, Shinjuku-ku / Shinkogawa-cho, Shinjuku-ku / Shinjuku, Shinjuku-ku / Suido-cho, Shinjuku-ku / Sugacho, Shinjuku-ku / Sumiyoshi-cho, Shinjuku-ku / Daikyo-cho, Shinjuku-ku / Takadanobaba, Shinjuku-ku / Tansu-cho, Shinjuku-ku / Tsukijicho, Shinjuku-ku / Tsukudo-cho, Shinjuku-ku / Chikudo Hachiman-cho, Shinjuku-ku / Tenjin-cho, Shinjuku-ku / Tozuka-cho, Shinjuku-ku / Fukukucho, Shinjuku-ku / Hyakunincho, Shinjuku-ku / Fukuro-cho, Shinjuku-ku / Funamachi, Shinjuku-ku / Benten-cho, Shinjuku-ku / Minami Enokicho, Shinjuku-ku / Minamimachi, Shinjuku-ku / Minamimoto-cho, Shinjuku-ku / Minamiyamanobori-cho, Shinjuku-ku / Yamabuki-cho, Shinjuku-ku / Yaraicho, Shinjuku-ku / Yokodera-cho, Shinjuku-ku / Yochō-cho, Shinjuku-ku / Yotsuya, Shinjuku-ku / Yotsuya Sakamachi, Shinjuku-ku / Yotsuya San’ei-cho, Shinjuku-ku / Yotsuya Honshio-cho, Shinjuku-ku / Wakaba, Shinjuku-ku / Wakamatsu-cho, Shinjuku-ku / Wakamiya-cho, Shinjuku-ku / Waseda Tsurumaki-cho, Shinjuku-ku / Waseda Minami-cho, Shinjuku-ku / Waseda-cho
Consultations via LINE are also very welcome◎
AAA is a young company with an average age in the early 20s, but our technology is second to none.
One of our greatest strengths is that we can do all of our own scaffolding, roofing, and painting work. In this industry, where work is generally divided, we are able to provide a complete set of services, which saves time and effort in management and reduces costs. Above all, if there is any trouble, we will come to you right away!
We can confidently declare this. We are the youngest and most friendly renovator in Kanagawa!





