What is FRP Waterproofing? Kakeru Koumuten Co., Ltd. Explains the Average Construction Costs, Advantages, and Disadvantages!

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There are various types of waterproofing work.

For those considering waterproofing for balconies and terraces, FRP waterproofing is recommended.

That said,

“What exactly is FRP waterproofing?”

I believe many people have this question.

In this article, we will explain in detail what FRP waterproofing is, the cost of FRP waterproofing, its lifespan, advantages and disadvantages, as well as maintenance methods for FRP waterproofing and checkpoints for FRP waterproofing deterioration, addressing various questions about FRP waterproofing.

What is FRP waterproofing?

FRP stands for “Fiber Reinforced Plastics,” and it has the characteristic of being excellent in waterproofing and strength among plastics.

The method of soaking resin into FRP mats and applying a top coat as a waterproof layer is called FRP waterproofing.

FRP waterproofing is widely used for waterproofing outdoor spaces. It is utilized not only for balconies and terraces but also for rooftops and bathrooms.

What are the advantages of FRP waterproofing?

Next, let’s take a closer look at the advantages of FRP waterproofing.

High waterproofing performance

Since FRP is a reinforced plastic, it has excellent waterproofing properties.

Thanks to this characteristic of FRP, FRP waterproofing work can prevent water leakage from rooftops and balconies, protecting the building.

As some of you may know, FRP is also used in items that require high waterproofing, such as

・bathtubs
・space rockets

and can be considered quite excellent in terms of “waterproofing ability.”

Strong against impact

FRP has the characteristic of being impact resistant.

Due to its strength, FRP is robust against external impacts and pressure, maintaining its effectiveness over a long period.

Therefore, it is suitable for areas where durability is required and where frequent foot traffic or use occurs.

The floor surface treated with FRP waterproofing will have:

・Load-bearing capacity
・Friction resistance

This makes it ideal for those who want to maintain durability.

Reduces the burden on buildings

The FRP waterproof layer is considerably lightweight at 4 kilograms per square meter, which reduces the burden on buildings.

While urethane waterproofing is also known for reducing the burden on buildings, FRP waterproofing excels in terms of lightweight properties, making it suitable for:

・Properties that have aged
・Houses that are sensitive to weight

and other waterproofing projects.

Relatively short construction period

FRP waterproofing work is completed in about 1 to 2 days.

This is because there is no need to wait for the coating to dry.

While the topcoat resin does require drying time, it dries in a few hours, making it a good option for those looking to finish quickly.

Additionally, it cures significantly faster than urethane waterproofing, which is also a type of coating waterproofing.

No seams

FRP waterproofing is also known as membrane waterproofing. The term membrane means “film” and is used in the context of coating waterproofing.

Unlike sheet waterproofing, which can vary based on the skill of the worker and may have seams, FRP waterproofing can form a waterproof layer even in complex shapes without seams.

Suitable for various applications

FRP waterproofing work is applicable not only for rooftops and balconies but also for various uses such as pools, tanks, and ships.

Thus, it can be widely utilized according to the structure and purpose of buildings and facilities.

What are the disadvantages of FRP waterproofing?

Next, let’s take a closer look at the disadvantages of performing FRP waterproofing.

Costly

 

 

 

 

FRP waterproofing work is relatively expensive. The cost of materials and the labor involved can reflect in the expenses, making it more costly compared to other waterproofing methods.

Difficulties in Repair and Maintenance

If cracks or damage occur in the FRP waterproof layer, repairs and maintenance can be challenging. Depending on the materials and construction methods, it may be difficult to repair just a part, necessitating a complete replacement.

Durability Limitations

 

 

 

 

 

While the FRP waterproof layer is highly durable, it is also vulnerable to ultraviolet rays, and over a certain number of years, deterioration and cracking can occur. Therefore, regular maintenance and repairs are necessary.

 

Considering these disadvantages, when contemplating FRP waterproofing work, it is important to compare the advantages and disadvantages and make an appropriate decision.

What is the Cost Range for FRP Waterproofing?

The cost of FRP waterproofing can vary depending on the construction location, but if we assume it is done on a balcony, it often ranges from 120,000 to 180,000 yen.

As for what the costs are attributed to,

Protection Costs	Approximately 10,000 yen
High-Pressure Washing	Approximately 10,000 yen
Base Repair	20,000 yen to 30,000 yen
FRP Waterproofing	50,000 yen to 80,000 yen

This is the format.

Of course, the above is just a guideline, and it may vary depending on the size and the contractor you choose, but for FRP waterproofing, this is generally the range of costs, so keep this in mind.

 

What are the differences between FRP Waterproofing and Urethane Waterproofing?

As explained earlier, FRP Waterproofing is a waterproofing method that forms a waterproof layer by impregnating and curing resin in a fiber-reinforced plastic called FRP.

Urethane Waterproofing is also classified as a coating waterproofing method, where liquid urethane resin is applied to the base, cured, and forms a waterproof layer.

Like FRP waterproofing, it can create a seamless waterproof layer even in narrow or complex shapes, making it suitable for various locations such as balconies, terraces, and rooftops.

Urethane waterproofing accounts for about half of the domestic waterproofing methods in overall waterproofing work, establishing it as a mainstream waterproofing construction.

Differences between FRP Waterproofing and Urethane Waterproofing

	FRP Waterproofing	Urethane Waterproofing
Unit Price (per m²)	4,000–8,000 yen/m²	3,000–7,500 yen/m²
Construction Period	1–2 days	3–10 days
Durability	10–20 years	8–12 years
Suitable Installation Locations	Balconies, areas with concrete substrates, and narrow spaces	Balconies, etc.
Unsuitable Installation Locations	Wood materials, iron substrates	High traffic areas

FRP Waterproofing Construction Process

1) Substrate Preparation

Prepare the substrate of the balcony. Ensure the flatness of the substrate and repair any cracks to create a solid foundation for adhering the FRP waterproofing sheet.

2) Surface Preparation and Cleaning

Surface preparation involves cleaning to remove dirt, old paint, and rust.

3) Application of Primer

The primer is a paint that has adhesive properties and is a necessary step to ensure the waterproof layer adheres firmly. By using a primer, it prevents the waterproof layer from peeling off, playing a crucial role in extending its lifespan.

4) Application of FRP Mat

The fiberglass FRP mat comes in sheet form and is cut for use.

The FRP mat is adhered to the substrate and impregnated with polyester resin.

5) Application of Topcoat

Finally, we apply the topcoat to finish. The topcoat does not have waterproof properties; instead, it serves to protect against ultraviolet rays.

6) Completion of FRP Waterproofing Work & Cleaning

Once the FRP waterproofing work is completed, we carry out cleaning in the surrounding area. We tidy up the construction site and conduct a final confirmation with the customer.

What is the Lifespan of the Topcoat and FRP Waterproof Sheet?

Topcoat Lifespan: 5 Years

The role of the topcoat is to protect the waterproof layer from ultraviolet rays, and the topcoat itself does not have waterproof performance.
The lifespan is approximately 5 years, and regular maintenance and inspections are essential.

As for topcoat paints, there are polyester-based ones that excel in abrasion resistance and urethane-based ones that have high elasticity and are easy to recoat.

FRP Waterproof Sheet Lifespan: 10 to 20 Years

The lifespan of the FRP waterproof sheet is between 10 to 20 years.

Generally, it is 10 years, and 20 years would indicate that the conditions have been exceptionally well-maintained for longevity.

Therefore, depending on the condition and circumstances, the lifespan of FRP waterproof sheets is superior compared to other waterproof sheets.

What are the Maintenance Methods for FRP Waterproofing?

We will explain in detail the maintenance methods for FRP waterproofing.

Reapplication of Topcoat

 

Cracks may indicate that the top coat is likely deteriorating.

If you leave this crack unattended, it can easily lead to water leaks, so maintenance needs to be performed immediately.

If cracks are present, we will repair it by repainting the top coat.

Even if there are no cracks, it is necessary to repaint approximately every 5 to 7 years, so make sure to perform maintenance at the appropriate timing.

Rework

If a water leak occurs, simply repainting the top coat will not solve the problem.

In this case, unfortunately, rework will be necessary.

Rework will incur more costs compared to just repainting the top coat, so if you discover cracks, it is recommended to address them promptly rather than leaving them unattended.

Checkpoints for FRP Waterproofing Deterioration

Next, we will introduce the checkpoints for FRP waterproofing deterioration.

1) Cracks and Lifting

If you see cracks or lifting on the surface of the FRP waterproofing sheet, it is a sign of deterioration. Especially due to temperature changes and building movements, the sheet may crack or lift.

2) Wear

On balconies or verandas with heavy foot traffic, the top coat will wear down over time. Wear refers to the reduction caused by friction. Areas with frequent walking are more prone to wear. While some wear is inevitable over time, it can also indicate a good time to consider repainting the top coat.

3) Peeling Paint

If the top coat applied to the FRP waterproofing sheet is deteriorating, it may lead to a decrease in waterproof performance. If the top coat is peeling or cracking, early maintenance is necessary.

4) Water Accumulation

If the surface of the FRP waterproofing cannot properly drain water, there is a possibility of water accumulation.

The causes of water accumulation can be due to not only the deterioration of the FRP waterproofing but also deficiencies in drainage systems, improper slopes, or clogged drainage outlets.

If water accumulation continues and is left unattended, the waterproof performance will decline, increasing the risk of water leaks and damage to the building. Regular inspections and maintenance are essential to prevent the deterioration of FRP waterproofing work.

5) Discoloration

If you see discoloration on the surface of the FRP waterproofing sheet, it may indicate that deterioration is progressing. Especially due to UV rays and rain, the surface of the sheet may deteriorate.

6) Condition of Surrounding Areas

Check the condition of the surrounding areas of the FRP waterproof sheet and its accessories (e.g., drainage outlets, pipe sleeves). If these parts are deteriorating, they may cause water leaks.

What to Do If There Is a Water Leak from the Balcony?

There is a water leak from the balcony! If such a leak has occurred, it means there is an entry point for rainwater somewhere.

In terms of deterioration, the waterproof layer is deteriorating and rainwater has seeped into the substrate. There is a high possibility that deterioration and corrosion are progressing in the waterproof layer of the balcony.

Especially in areas where the leak is serious, the substrate may be corroded, and stepping on it may feel spongy. In such situations, there is a risk that a hole could form in the balcony, causing the bottom to collapse, so prompt action is necessary.

If the waterproof layer of the balcony has already corroded down to the substrate, the existing substrate cannot be used, so it will be replaced with a new substrate, and waterproof work will be carried out on the balcony. An important point here is to create a moderate slope to promote drainage.

No matter what waterproof method is used, the underlying substrate is an important point, so even if it is not usually visible, be sure to pay attention to the condition of the internal surfaces during maintenance and inspections!

How to Make Balcony Waterproofing Last Longer?

Next, I will introduce methods to make balcony waterproofing last longer, not limited to FRP waterproofing.

Regular Cleaning of Drains and Floors

It is advisable to clean the floor of sand, dust, and fallen leaves with a broom or vacuum cleaner at least once every 3 months.

If you have potted plants or trees on the balcony, it is recommended to clean more frequently due to the higher likelihood of dirt from moss and soil, so a shorter frequency is suggested.

It is also important to regularly clean the drains. If the drains are clogged with soil, leaves, or debris, normal drainage will be hindered, causing sewage to overflow and the waterproof layer to deteriorate.

For stubborn stains on the floor, use a deck brush or scrubbing brush, and dilute commercially available detergents to an appropriate concentration, being careful to avoid leaving any detergent residue.

Additionally, when scrubbing with a brush like a scrubbing brush, it is important to avoid scratching the waterproof layer, so be cautious about over-scrubbing and the tools used.

Repainting the Top Coat

As mentioned, the lifespan of the top coat is about 5 years, but regular repainting of the top coat can minimize the deterioration of the waterproof layer, not just for FRP waterproofing, and help protect it.

Laying a Wooden Deck on the Floor

This protects against UV rays and prevents falling objects from damaging the floor. However, if the wooden deck is not durable, it may hinder the flow of rainwater, potentially accelerating the deterioration of the waterproof layer, so it requires effort to regularly clean under the wooden deck.

Can FRP Waterproofing Be Done as a DIY Project?

To get straight to the point, I cannot recommend doing the topcoat repainting of FRP waterproofing as a DIY project.

While it is possible to prepare materials yourself at home improvement stores to save some money on repairs,

・it can be difficult to assess the state of deterioration, and there is a risk of missing the fact that the waterproof layer has deteriorated.

・There is also a high possibility of failure, and if you make a mistake, you will have to redo the entire project to revert it, which will incur additional costs.

・Using FRP waterproofing paint, which can be hazardous, makes it difficult without proper knowledge.

For these reasons, I cannot recommend conducting FRP waterproofing work as a DIY project.

I believe that obtaining estimates from specialized contractors who can do the work at a reasonable price is a better way to have FRP waterproofing done more affordably.

Customer Testimonials from Those Who Have Had FRP Waterproofing Done

Q&A About FRP Waterproofing Work

Conclusion

That concludes the explanation of various questions regarding FRP waterproofing.

FRP waterproofing is a method of waterproofing construction that excels in waterproofing and durability.

Additionally, FRP waterproofing often takes about one to two days to complete, making it a recommended method for those who want it done quickly.

However, as mentioned earlier, the FRP waterproofing method has some drawbacks, including:

・It can be costly

・Repairs and maintenance can be difficult

There are also disadvantages like this, so we recommend proceeding with an understanding of these disadvantages.

That said, for those without knowledge of waterproofing work,

it may lead to a state of

“not knowing if FRP waterproofing is suitable.”

If you find yourself in such a situation, please feel free to consult with Kakeru Koumuten Co., Ltd.!

Waterproofing work is essential for areas prone to leaks such as roofs, balconies, and verandas.

If you have concerns like “the waterproof layer is deteriorating,” “part of the veranda is torn,” or “it might be leaking,” please don’t hesitate to contact Kakeru Koumuten Co., Ltd.

Helpful information about exterior renovations can be found here!

Leave FRP waterproofing work to Kakeru Koumuten!

Estimates and inspections are, of course, free! If you have any issues with roofs, rain gutters, exterior walls, or exteriors, please consult with Kakeru Koumuten Co., Ltd. in Aoba-ku, Yokohama!

Kakeru Koumuten is a renovation company strong in exterior renovations, and we carry out complete in-house construction from temporary scaffolding to roofing and exterior painting.
We are confident that in terms of “cost, quality, and efficiency”, we do not fall behind compared to other companies!
We are confident in our exterior renovations, so we welcome competitive estimates!
With comprehensive construction guarantees and aftercare maintenance, we have received positive feedback for our proposals that align with cost performance and our customers’ future life plans!

We are committed to taking your requests seriously so that you can think, “I’m glad I asked!”

We also have information on roofing costs and pricing plans for roof overlay methods, so please take a look if you’re interested!

We look forward to your inquiries. Thank you very much.

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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!

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