If you are looking for a waterproofing contractor in Aoba-ku, Yokohama
Contact Kakeru Koumuten
Kakeru Koumuten is a company specializing in exterior renovations based in Yokohama.
We receive many requests for waterproofing work in Aoba-ku, Yokohama, ranging 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 subsidies and grants applicable to waterproofing work in Aoba-ku”
We will explain the above four points!
This will definitely be helpful 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 can be entrusted with waterproofing work by customers in Aoba-ku, Yokohama,
One reason is that we have a base in Yokohama City, but
“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 everything is handled by our company, we can significantly reduce costs by shortening the construction period!
We have enough scaffolding materials for approximately 50 single-family homes!
Storage of materials in our large company 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!
Sorting of waste materials in-house
In waterproofing work, various waste materials are generated.
Most contractors dispose of them all together, but by sorting and recycling the 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.
2.Complete In-House Construction
One of Kakeru Koumuten’s major strengths is its 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 construction industry permits and permits for industrial waste collection and transportation!
We also have national qualified personnel 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 respond accordingly!
Additionally, aftercare maintenance is available annually, and we will send you a DM reminder for aftercare maintenance each 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 surveys 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 may cause issues, so we maintain 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 so that each staff member can handle various types of buildings.
Subsidies and Grants for Waterproofing Work in Aoba-ku, Yokohama
If damage due to natural disasters is recognized, it may be covered by fire insurance.
Examples of damage considered under waterproofing due to natural disasters include “holes in waterproof sheets caused by flying objects or falling debris due to wind damage.”
If you are unsure whether your fire insurance applies, please feel free to contact us!
Property Tax Reduction System for Condominiums with Major Repairs (Condominium Longevity Promotion Tax System)
To promote the longevity of condominiums, there is a system that reduces the property tax amount by half for the following fiscal year for condominiums that meet certain requirements and undergo major repairs contributing to longevity between April 1, 2023, and March 31, 2027, provided that the necessary documents are submitted to the Tax Division of the Ward Office within three months of the completion of the work.
Condominium Longevity Promotion Tax System
Yokohama City Official Website
About the Costs of Waterproofing Work
⇧Construction Menu|For information on waterproofing costs, click here
Examples of Waterproofing Work
| Construction Details |
| Urethane waterproofing ventilation buffer 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 Vent 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 rooftop, 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. ・Since 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 rooftop.
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 across the entire area before applying urethane waterproofing.
By applying the ventilation buffer sheet first, air rising from the building is suppressed by the ventilation sheet and expelled 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 the project to us among the four estimates you received!
Timing for Waterproofing Work
Leaks Already Occurring
If leaks have already occurred, it is necessary to address the issue promptly before the damage spreads.
If left unattended, it can negatively affect the interior and underlying structures, so it is essential to stop the leaks quickly.
Bulging or Cracking of 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.
Bulging 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 accumulated 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 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 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 onto the waterproofing surface.
Before curing, it is in liquid form, allowing it to be applied even on 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 details 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 commonly used on 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 details 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.
Like rubber sheets, it is not suitable for complex shapes. Although the cost is higher than rubber sheets and urethane waterproofing, its durability is a significant advantage.
For more detailed information on the advantages and disadvantages of PVC sheet waterproofing, as well as maintenance methods, please refer to the article below.
For waterproofing work | Click here for PVC sheet waterproofing work!
4. Long Sheet Waterproofing
Long sheet waterproofing, officially known as “slip-resistant vinyl floor sheet,” is commonly used in shared areas and staircases of condominiums 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 have a slightly lower impression of waterproofing capability.
It is rarely used in areas like the rooftops of condominiums where people do not frequently enter and exit.
For more detailed information on the advantages and disadvantages of long sheet waterproofing, as well as maintenance methods, please refer to the article below.
For waterproofing work | Click here for long sheet waterproofing work!
5. FRP Waterproofing
FRP waterproofing involves creating a waterproof layer by solidifying glass mat with epoxy resin to prevent rainwater intrusion.
It is commonly used in single-family home balconies, 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 single-family home balconies use FRP waterproofing.
However, it is not suitable for construction on large surface areas, making it less appropriate for rooftops.
For more detailed information on the advantages and disadvantages of FRP waterproofing, as well as 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 type of waterproofing is used in buildings with large areas such as rooftops of schools and commercial facilities.
There are various methods of asphalt waterproofing, each with its own advantages and disadvantages, but a significant advantage 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 Aoba-ku, Yokohama.
Among the numerous contractors, I believe many people feel “I don’t know who to ask…”.
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 existence 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 trustworthy 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 reliable contractor with experience!
You need to refer to the contractor’s website for their construction achievements and reviews to make a judgment.
Some contractors showcase their achievements on social media platforms like Instagram, so checking those can also be effective!
It is also effective to refer to review sites to look for waterproofing companies!
The review site we particularly recommend is “Google”.
Since contractors cannot delete low ratings on their own, it provides trustworthy 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 any construction defects or issues occur after the work, let’s confirm if they provide a “construction warranty”!
Contractors who offer warranties are usually confident in their work, making them more trustworthy!
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 communication will be smoother shortly after the work is completed!
Also, to ensure early detection of any issues that may arise, confirm if they provide thorough aftercare maintenance!
If the contractor is not a specialist, they may not notice signs of problems or troubles, so having a specialized contractor perform regular aftercare maintenance can help prevent issues 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, be sure to 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 price negotiations easier. To secure the best price, it is essential to get estimates from several contractors.
When comparing estimates, check not only the costs but also the details such as “types of materials used” and “construction methods”!
Confirm if they perform waterproofing work in-house
Check if they carry out waterproofing work in-house!
If a sales company investigates and then requests a subcontractor, it will take extra time and cost.
Moreover, there may be cases where customer requests are not fully communicated to the subcontractor, leading to troubles.
By having one company handle everything from sales to construction, responsible waterproofing work can be done quickly and cost-effectively. Kakeru Koumuten conducts everything from on-site surveys to actual construction in-house!
Furthermore, if any leaks or troubles occur, a company that has its own craftsmen can respond to and resolve issues quickly!
Carefully Check the Details of Waterproofing Estimates, Processes, and Materials
Even for the same waterproofing work, there are various types such as “methods,” “materials,” and “processes,” and it is necessary to carry out the work using the most suitable method and materials depending on the construction location and existing substrate.
For example, even with the same urethane waterproofing, there are different types of processes such as “adhesion method” and “ventilated buffer method,” and there are various types of urethane waterproofing materials, including “high-strength specifications,” “heat-insulating specifications,” and “anti-slip specifications.” Therefore, it is essential to confirm whether the construction content is appropriate for the installation location!
It is important to check in detail, not just based on cost, whether “the method is appropriate for the base material?” and “are the materials suitable?”
So, if the materials used are only “urethane waterproofing materials,” let’s check the product name to confirm what kind of materials they are!
If you are looking for a waterproofing contractor in Aoba-ku, Yokohama, please contact Kakeru Koumuten Co., Ltd.
Our company has handled many waterproofing projects in Aoba-ku, Yokohama.
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 high praise from many customers.
We continue to update our number of completed projects each year, and we will strive to improve quality to satisfy even more customers in the future.
We are happy to handle even small partial projects!
In addition to waterproofing work, we can also carry out roofing work, exterior painting, and exterior covering methods, all 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 welcome to decline!
For exterior renovations in Aoba-ku, Yokohama, click here!
For exterior painting in Aoba-ku, Yokohama, click here!
For roof renovations in Aoba-ku, Yokohama, click here!
For exterior covering work in Aoba-ku, Yokohama, click here!
For leak repairs in Aoba-ku, Yokohama, click here!
Characteristics of Aoba-ku, Yokohama
Seya-ku is located on the western side of Yokohama City, an area where nature and a quiet residential environment harmonize, making it an attractive region for those who wish to lead a peaceful life.
The biggest feature of this ward is its rich natural environment, with many green spaces and parks scattered throughout, allowing residents to enjoy seasonal landscapes.
There are plenty of places to refresh in nature, such as walking and jogging paths, making it ideal for those seeking a lifestyle away from the hustle and bustle of the city.
It has developed as a residential area, with many single-family homes and apartments, wide roads, and calm streets providing a comfortable living environment.
Additionally, it is home to many families and seniors, with facilities for child-rearing, schools, and lush parks, making it a suitable area for raising children.
Transportation is convenient, with access to Yokohama city center and Tokyo via railways and major roads, and the environment is also suitable for traveling by car.
Furthermore, the local community is active, with shopping streets and community events deepening connections among residents, allowing newcomers to settle in comfortably. Seya-ku offers a peaceful living environment surrounded by nature and tranquility while enjoying the conveniences of urban life, making it an ideal place for families, seniors, and nature lovers.
If you live in Seya-ku and have any concerns regarding waterproofing work or your home, please feel free to contact us!
Waterproofing Service Areas
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and Tokyo.
List of Areas in Seya-ku, Yokohama
Seya-ku, Yokohama Aizawa / Seya-ku, Yokohama Akigawa Nishi / Seya-ku, Yokohama Akigawa Higashi / Seya-ku, Yokohama Akigawa Minami / Seya-ku, Yokohama Higashino / Seya-ku, Yokohama Higashino Dai / Seya-ku, Yokohama Oroshimachi / Seya-ku, Yokohama Kamiseya / Seya-ku, Yokohama Kitashin / Seya-ku, Yokohama Kitamachi / Seya-ku, Yokohama Gokanmachi / Seya-ku, Yokohama Shimoseya / Seya-ku, Yokohama Seyamachi / Seya-ku, Yokohama Seya / Seya-ku, Yokohama Takemuracho / Seya-ku, Yokohama Chuo / Seya-ku, Yokohama Nakayashiki / Seya-ku, Yokohama Hashido / Seya-ku, Yokohama Futatsubashi / Seya-ku, Yokohama Hongō / Seya-ku, Yokohama Mitsuzaka / Seya-ku, Yokohama Minamiseya / Seya-ku, Yokohama Minamidai / Seya-ku, Yokohama Miyazawa / Seya-ku, Yokohama Megurocho
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!





