If you are looking for a waterproofing contractor in Konan-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 Konan-ku, Yokohama, ranging from single-family homes to apartment buildings.
“Reasons why Kakeru Koumuten is chosen in Konan-ku”
“About the costs of waterproofing work”
“How to choose a waterproofing contractor”
“Subsidies and grants available for waterproofing work in Konan-ku”
We will explain the above four points!
This will definitely be helpful for customers considering waterproofing work in Konan-ku, Yokohama, so
please take a look!
Reasons why Kakeru Koumuten is chosen for waterproofing work in Konan-ku, Yokohama
The reasons why our company is entrusted with waterproofing work by customers in Konan-ku, Yokohama include
the fact that we have a base in Yokohama,
and our unique strengths in waterproofing work that cannot be imitated by other companies, which have received high praise from many customers.
We are absolutely confident in “cost,” “quality,” and “plans,” so we would be grateful 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 organized the following warehouses and material storage areas to provide more affordable and faster waterproofing and other exterior renovations.
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 performing scaffolding work with our own scaffolding team instead of outsourcing, we can also reduce the costs associated with scaffolding work.
Since everything is handled in-house, 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 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 sorting 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 reductions in waste disposal fees can be achieved.
Exterior Renovation Dedicated Showroom


In our showroom, not only can you have meetings, but you can also
directly check the actual structure 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. This allows 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 competitive estimates are very welcome!
3. Various Permits and Skilled Workers

We have obtained permits for construction work and industrial waste collection and transportation!
We also have 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 warranty.
If you have any questions about the warranty, 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 every year, 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 roof for waterproofing checks, we will use drones and other tools 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 problems, so our company maintains a system where the representative remains the same.
6. Human Resource Development
To improve 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 Konan-ku, Yokohama
If damage caused by natural disasters is recognized, it may be covered by fire insurance.
For waterproofing, potential damage from natural disasters may include “holes in waterproof sheets caused by flying objects or falling debris due to wind damage.”
If you are unsure whether it is covered by fire insurance, 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, for those that meet certain requirements, if major repairs contributing to longevity are carried out between April 1, 2023, and March 31, 2027, and necessary documents are submitted to the Tax Division of the Ward Office within three months of the completion of the work, there is a system that reduces the property tax amount for the following fiscal year by half for the relevant condominium.
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
| Work 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 |
| About 2 weeks |
| Completion Month |
| May 2024 |
| Inquiry Details |
| We 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 waterproofing 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 roof.
If urethane waterproofing is applied using a direct 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 expelled through a “ventilation pipe.”
This can prevent the most common problem in 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
Already Experiencing Leaks
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.
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 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 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.
Before curing, it is in liquid form, allowing it to be applied to complex shapes and eliminating seams, which is a significant advantage over sheet waterproofing.
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 method is commonly 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 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, and like rubber sheet waterproofing, it 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, disadvantages, and maintenance methods of PVC sheet waterproofing, 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 “anti-slip vinyl floor sheet,” is commonly used in shared areas and staircases of apartments 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 ability.
It is rarely used in areas like apartment rooftops where people do not frequently enter.
For more details on the advantages, disadvantages, and maintenance methods of long sheet waterproofing, 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 installation on uneven surfaces, making it less appropriate for rooftop applications.
For more details on the advantages, disadvantages, and maintenance methods of FRP waterproofing, 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 detailed information 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 Konan-ku, Yokohama.
Among the numerous contractors, there are likely many who feel “I don’t know who to ask…”.
Choosing the right contractor can be challenging at first, so here are 5 points to keep in mind 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 details of the waterproofing estimate, including 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 construction troubles are caused by poor workmanship during 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 past work 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 look at waterproofing companies using review sites for reference!
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 defects or issues arise after construction, 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 the hidden areas during the process for confirmation!
Check for leaks during rainy weather after the waterproofing work, and if there are any issues, 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 whether they provide thorough aftercare maintenance!
Since non-specialized contractors may not notice signs of problems or troubles, having a specialized contractor conduct 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 for waterproofing work (at least 3 companies)
When requesting waterproofing work, be sure to obtain estimates from multiple contractors.
We recommend obtaining estimates from at least 3 companies.
Even for the same waterproofing work, costs may vary between contractors, as well as warranties and after-service offerings.
Moreover, obtaining multiple estimates makes it easier to negotiate prices. To request at the lowest possible cost, obtaining estimates from multiple contractors is essential.
When comparing estimates, check not only the costs but also the details such as “types of materials used” and “construction methods”!
Check if they perform waterproofing work in-house
Confirm whether they carry out waterproofing work in-house!
If a sales company investigates and then requests a subcontractor, it will incur additional time and costs.
Also, there may be cases where customer requests are not 100% 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 handles everything from on-site surveys to actual construction in-house!
Furthermore, if any leaks or troubles occur, a company that employs 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 site 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 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,” let’s confirm the product name and check 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 carry out 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 construction performance every year, and we will strive to improve quality to satisfy even more customers in the future.
We are happy to handle even small partial works!
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 efficiency in 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!
Click here 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!
Characteristics of Aoba-ku, Yokohama
Konan-ku is located in the southern part of Yokohama City, an area where a lush environment coexists with convenient urban functions.
With well-developed railways and bus routes such as the Yokohama Municipal Subway Blue Line, Keikyu Main Line, and JR Negishi Line, commuting to and from central Yokohama and surrounding areas is convenient, making it suitable for both work and school. Additionally, there are spots within the ward where you can feel the local history and culture, making it not only a livable area but also one where you can enjoy the charm of the region.
Moreover, the area is characterized by a wealth of commercial and entertainment facilities, providing high convenience for shopping and daily needs.
If you live in Konan-ku and have any concerns regarding waterproofing work or anything related to your home, please feel free to contact us!
Waterproofing Work Service Areas
Kakeru Koumuten Co., Ltd. accepts requests throughout Kanagawa Prefecture and Tokyo Metropolis.
List of Areas in Yokohama City, Konan-ku
Okubo, Konan-ku, Yokohama / Kamiooka Nishi, Konan-ku, Yokohama / Kamiooka Higashi, Konan-ku, Yokohama / Kamenagaya-cho, Konan-ku, Yokohama / Kamenagaya, Konan-ku, Yokohama / Konandai, Konan-ku, Yokohama / Konan Chuo-dori, Konan-ku, Yokohama / Konan, Konan-ku, Yokohama / Saito, Konan-ku, Yokohama / Sasashita, Konan-ku, Yokohama / Shimonagaya, Konan-ku, Yokohama / Serigaya, Konan-ku, Yokohama / Noba-cho, Konan-ku, Yokohama / Higashi Serigaya, Konan-ku, Yokohama / Higashi Nagaya, Konan-ku, Yokohama / Higeyama, Konan-ku, Yokohama / Hino Chuo, Konan-ku, Yokohama / Hino Minami, Konan-ku, Yokohama / Hino, Konan-ku, Yokohama / Maruyama-dai, Konan-ku, Yokohama
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!





