Points and Precautions to Compare When Getting Multiple Estimates for Roof Renovation in Kawasaki City!

Hello! This is Kakeru Koumuten Co., Ltd.!

We are Kakeru Koumuten, a specialist in exterior renovations! We receive many requests for roof renovations and repairs within Kawasaki City.
On this page, we will explain important points and comparison points when obtaining estimates for roof renovations in Kawasaki City!

To conclude, the most important thing in roof renovation work is
to obtain estimates from at least three companies.

While it is certainly preferable to have lower costs when obtaining estimates, deciding on a contractor based solely on the estimate cost can be risky.

Roof renovation work, excluding partial roof repair work, can be mainly divided into the following three types.

・Roof overlay (cover method) work
・Roof replacement work
・Roof painting work

Since the above works involve a complete roof renovation, they typically range from hundreds of thousands to millions of yen.
When it comes to roof overlay or replacement work, it is crucial to compare and confirm not only the “main roofing material” but also the “sub-materials” and “processes” to avoid mistakes.

It is necessary to carefully consider roof renovation work to avoid regrets years later.
To confidently request a roof renovation, it is important to identify a trustworthy contractor.

To identify a reliable contractor, you must obtain estimates from the contractors you are interested in and consider them based on the estimate documents.

That said, among those who are requesting roof renovation work for the first time,

there are likely many who have such questions.

In this article, we will explain in detail the following:

How to decide on the contents of a roof renovation, and
Key points and important items to compare in actual roof renovation estimates
for each type of roof renovation work!

7 Points You Should Know When Getting a Roof Construction Estimate

 There are six main points to be aware of when getting a roof renovation estimate.

We will explain each point in detail!

1. Always obtain multiple estimates and compare them

As mentioned earlier, the most important thing in roof renovation work is obtaining multiple estimates.

Obtaining multiple estimates means requesting estimates from several contractors and comparing them.

There are many contractors that serve the Kawasaki City area, and even for the same work, the construction methods and materials used can vary by contractor.
Therefore, the costs can differ significantly depending on the contractor you choose.

If you decide based on just one estimate, you may not realize you are being charged more than the market rate, even if the requested work is the same.
By comparing multiple companies, you can understand the appropriate construction content and price range.

If you proceed without obtaining multiple estimates,

“There might have been a cheaper contractor…”
“I experienced leaks before the promised durability period…”
“I contacted them about issues, but couldn’t get in touch…”

As such, the likelihood of failure or regret increases, which is why we at Kakeru Koumuten recommend obtaining multiple estimates to all our customers.

Some contractors may strongly dislike the idea of getting multiple estimates and may pressure you with statements like,
“If you sign now, we can offer a discount.”
“Material prices are going up.”
“If you don’t start the work soon, you’ll need more expensive repairs.”
It’s important not to rush into a contract and to take the time to get multiple estimates!

If you are experiencing leaks, it’s crucial to perform temporary measures and make a calm judgment!
Kakeru Koumuten can also provide emergency measures for leaks!

2. Check if the contents of the estimate differ too much from other companies

When obtaining multiple estimates, it’s also important to check if the contents differ significantly from other companies.

It’s not uncommon for the area of work to be excessively large or the price to be too high.
While it’s not necessarily a problem if there are significant differences in price or work details, make sure to ask the contractor for clear reasons why their estimate differs from others.

Even if the price is low, if the estimate has extremely few items listed, there may be a possibility that necessary materials have been cut to reduce costs, so be cautious!

3. Confirm if there is a breakdown of materials and other details

When you receive an estimate for roof renovation from a contractor, make sure to check if there is a detailed breakdown.

Some contractors may only list “one set,” but this does not clarify how much money is allocated to what.

Moreover, if the contractor can freely adjust the amounts, there is a high possibility that the price could be inflated.

We recommend contractors who provide a detailed breakdown of costs.

Especially for roofing work, be sure to confirm the types of roofing sheets and ridge materials (nail boards)!
Since roofing sheets and ridge materials cannot be checked after installation, ensure that inexpensive materials are not being used to cut costs!
Contractors who clarify their pricing will give you peace of mind when entrusting them with your project.

4. Check if insurance or subsidies in Kawasaki City can be used

To reduce the cost of roofing work, let’s check with the contractor whether fire insurance or subsidies can be utilized.

For example, if the roof is damaged due to a typhoon or strong winds, there is a possibility that part or all of the repair costs can be covered by fire insurance.
Additionally, roof painting using heat-insulating paint or roof replacement work aimed at improving seismic performance may be eligible for subsidies from local governments.

Using fire insurance or subsidies requires separate procedures.
If the contractor has previously utilized fire insurance or subsidies for past roofing work, you can trust them with confidence.

Subsidies and Grants That May Be Applicable for Roof Renovation in Kawasaki City

In Kawasaki City, the following subsidies may be available for leak repairs and roof repairs.
For details, please contact our company or your local government.

Dispatch Project for Wooden House Seismic Diagnosis

This system aims to create a safe city resilient to earthquakes, where Kawasaki City conducts “seismic diagnosis” for wooden individual houses. The city dispatches “certified wooden house seismic diagnosticians” approved by the mayor to conduct investigations for citizens wishing to have a seismic diagnosis, supporting their seismic measures.

Information on the Kawasaki City Wooden House Seismic Diagnosis Dispatch Project

https://www.city.kawasaki.jp/500/page/0000002325.html

Wooden House Seismic Renovation Subsidy System

The Kawasaki City Wooden House Seismic Renovation Promotion Project is a system where the city subsidizes part of the costs for seismic renovation work on wooden individual houses.

About the Earthquake Resistance Renovation Subsidy System for Wooden Houses in Kawasaki City

https://www.city.kawasaki.jp/500/page/0000032250.html

5. Is the roof renovation aligned with your life plan?

When considering construction, it is essential to confirm whether it is a
“roof renovation that aligns with your life plan and needs?”

“I plan to demolish the house or move in 10 years”
“I am considering a roof renovation because the second floor is hot”
“I am considering a roof renovation due to leaks”

You may be considering a roof renovation due to triggers or concerns like the above.

For example, if you have decided to move or demolish in 10 years, using highly durable roofing materials with a lifespan of over 40 years, such as the “roof overlay (cover method)” or “roof replacement work,” would be a waste of money.
You need to consider using roofing materials with a lower lifespan and cost, or roof painting as one of the options.
Similarly, if the goal of the roof renovation is to improve heat resistance and insulation due to heat, performing a roof replacement or overlay with standard roofing paint or low-insulation roofing materials will not achieve the intended purpose and will result in wasted work.

Additionally, for customers considering roof painting, the most important thing to pay attention to is “the type of roofing material currently used on the building”.
When painting the roof, if the existing roofing material is slate (colonial) roofing, there are roofing materials that cannot be painted, so it is necessary to confirm the type of existing roofing material.
If you paint roofing materials such as “Colonial NEO” or “Pamir,” which cannot be painted, it will result in wasted construction costs.

There are many contractors who will casually propose painting on roofing materials that cannot be painted, so caution is necessary.
For roofing materials that cannot be painted, let’s perform appropriate roof renovations such as “roof overlay (cover method)” or “roof replacement”!

For details on roofing materials that cannot be painted, click here!

6. Check the contents of the warranty and after-support

Depending on the construction details, there is a possibility that the work may not turn out as the customer expected. It is recommended to choose a contractor who explains the warranty and after-support in advance, in case any troubles occur.
Regarding the warranty details, it is important to confirm not only the warranty period but also how far the coverage extends, such as “leakage warranty” and “detachment of roofing materials and accessories.”

How long is the warranty period? What kind of after-support is available? Be sure to check these during the estimation process.

When using the roof overlay method or re-roofing, be sure to obtain a “manufacturer’s warranty.”

7. Confirm if the construction plan is suitable for the location and natural environment of Kawasaki City

Kawasaki City has areas with strong winds and locations close to the sea, such as Kawasaki Ward.
If you are near the sea, there is a possibility that the “manufacturer’s warranty” may not apply to certain roofing materials.
In areas with strong winds, it is necessary to ensure that the ridge base and fasteners for the roofing materials are designed to withstand strong winds.
By thoroughly checking not only the costs but also the building’s location and the warranty conditions of the proposed roofing materials, you can reduce the likelihood of troubles after the construction.

Always confirm whether the plan is suitable for the building’s location and conditions!

【Kawasaki City】 Roof Renovation Estimation Procedure

We will explain in detail the steps to request an estimate for roof renovation.

Specifically, the process is as follows:

Generally, most contractors provide services for free, but it’s reassuring to confirm whether there will be any costs involved!
Next, I will explain in detail about the estimates when carrying out roofing work.

1. Research contractors that operate in Kawasaki City

Currently, most contractors have their information listed on the internet or on signboards, so you can look there.
Also, when searching for contractors, it’s advisable to get multiple estimates and look for several contractors.
By keeping in mind the seven points mentioned earlier, the chances of making a mistake will be reduced.

In the case of the internet, there are comparison sites where you can check multiple contractors at the same time, but be careful as a commission fee will be added to the estimate with a 100% probability.

In other cases, advertisements may be placed on public transportation like buses and trains, or flyers may be delivered to your home. If you’re interested, it might be worth contacting them once.

That said, narrowing down from the many contractors can be quite challenging.
Therefore, reading reviews on Google and similar platforms is a reliable method to focus on companies with high ratings and inquire with them.
Google reviews are difficult to remove even if they are negative, making them quite credible!

2. Request an estimate

To narrow down quality contractors from roofing estimates, it’s important to request at least three companies.
With only one or two companies, it becomes difficult to compare the contents, increasing the likelihood of not finding a quality contractor. By obtaining estimates from three or more companies, you can compare prices, service contents, and responsiveness, making it easier to find a suitable quality contractor.

Additionally, when obtaining multiple estimates, ensure that they are created under the same construction conditions.
If the conditions vary, it becomes difficult to compare costs and construction details due to excessive differences.

3. Have a site survey conducted

Once you have requested an estimate, have the contractor conduct a site survey.
Since the contractor will come to your home, be sure to ask any questions you have regarding the construction at that time.

Examples of questions you might want to ask include:

Also, be cautious of companies that provide estimates based only on floor plans or elevation drawings without measuring the actual roof.
Depending on the shape of the roof, it is difficult to accurately determine quantities from floor plans or elevation drawings, and measuring the lengths of ridges and fittings in actual dimensions is indeed more accurate.

Additionally, by checking the existing roofing materials, you can propose more optimal materials and construction details.

4. Compare the estimates

When you receive estimates from multiple contractors, please compare the estimates from each company.
The three key points to pay attention to are as follows:

Let’s explain the specific points to be careful about.

1. Check if the product name and manufacturer name are listed

Make sure that the details such as the paint and materials used for the roofing work, as well as the manufacturer names, are clearly stated.
If there are any unclear parts, be sure to confirm with the contractor.

2. Check if the area and unit price are listed

Always confirm that the construction area is not abbreviated as “one set.”
Contractors that provide detailed area specifications are likely to have conducted a more accurate survey and can be trusted.

If the majority of the area in the estimate is listed as “one set,” please be cautious.

3. Check if the process and specifications are listed

Also, check if detailed processes such as “scaffolding assembly” and “substrate treatment” are included.
If appropriate processes are listed, there should be at least 10 items.

If the processes are grouped together as “painting work as a whole” or “roofing work as a whole,” or if the product names for the battens or roofing sheets in roof cover work or roof replacement work are not listed, it is difficult to understand the details, so caution is necessary.

Comparison Points for Each Type of Roof Renovation Estimate

Finally, we will introduce the essential items to check in the estimates for the three typical types of roof renovation work listed below!
If the items we are about to explain are not included in the estimate, we recommend confirming with the contractor whether they are part of the work!

① Roof Painting
② Roof Cover Work
③ Roof Replacement Work

We will explain the essential items to check in the estimates for the three types of roof renovation work mentioned above!
The installation of temporary scaffolding (including mesh sheets) is a mandatory item for all works, so we will omit it from here on!

1. Comparison Points for Roof Painting Estimate Items

First, I will explain the important items for roof painting work in detail by process!

1. High-Pressure Washing

The entire roof will be washed with high pressure. If the dirt is severe, bio-cleaning is recommended.

2. Protection

We will protect areas that may get dirty during the roof painting, such as near the exterior walls.

3. Surface Preparation

We will repair cracks in the roof and scrape off any old paint or dirt that could not be removed during washing.
We will also scrape off rust from the metal parts.

4. Rust Prevention for Metal Parts

We will apply rust prevention paint to metal parts such as sheet metal and snow stops.
If this item is omitted, it is common not to apply rust prevention, which increases the likelihood of rust developing on metal parts within a few years, so caution is necessary.

5. Primer Application

There are different types of primers, and it is necessary to choose a primer suitable for the existing roofing material and condition.
For example, metal roofs require the use of a primer or undercoat.
If the existing roofing material is slate and water-based paint has been applied, using a solvent-based paint without a dedicated primer can cause the paint film to shrink.
To prevent issues, it is necessary to use a primer that matches the substrate and condition to ensure the longevity of the paint film.

Be sure to understand the condition of the substrate and check if a dedicated primer is being used!

6. Installation of Taspacer (Separation Material)

This is an item necessary only for slate roofs.
Slate roofs are designed to allow rainwater and moisture to escape from the overlaps of the roofing material.
If the overlaps of the roofing material are filled with paint during roof painting, it will reduce ventilation, leading to substrate corrosion and potentially damaging the roofing material.

Therefore, installing taspacers after priming will ensure gaps in the overlaps of the roofing material.

It is generally necessary to install 2 taspacers for each slate, and the installation positions are predetermined.
However, taspacers cannot be installed on roofing materials that are warped more than 4mm.

If the estimate does not include a line item for the spacer, let’s check the reason!
Also, if the number of “spacer installations” is not listed, it is necessary to confirm whether the work will be done according to the standard number of units.

7. Intermediate and Top Coats

Basically, roof painting involves three coats, including the primer, intermediate, and top coats.
This item is often included by most contractors, but if it is not listed, be sure to confirm!
There are differences in durability and heat resistance among the intermediate and top coat paints, so it is recommended to carefully decide which paint best meets your needs rather than just going by price.

Rafter Replacement

This is not related to the roof painting process, but if you are painting a slate roof that is over 10 years old, it is advisable to detach part of the ridge cap to check the condition of the rafters.
If the existing rafters are made of cedar, their durability is around 10 to 15 years, so replacing them together can reduce costs compared to doing a standalone rafter replacement.
Let’s at least get an estimate and consider it!

There are also types of rafters such as “wood” and “resin,” which have different durability, so

“What kind of material will be used for the new rafters?”
“Will the ridge cap fasteners be nails or screws?”

Make sure to check these points as well!

Here is the price list for Kakeru Koumuten’s roof painting work!

2. Comparison Points for Roof Overlay (Cover Method) Estimate Items Comparison Points

The roof overlay method involves installing new roofing materials over the existing slate roof without dismantling it.
We will explain the important processes and items involved in the roof overlay method!

1. Dismantling Existing Ridge and Snow Stops

We will dismantle areas such as the existing ridge cap, rafters, and snow stops that interfere with the cover method.

2. Underlayment Installation (Roofing Sheet)

This item involves applying a waterproof sheet to the existing roof.
This is an item that should be carefully compared!

To conclude, there are two points to check:
“Is the durability of the roof itself balanced with the durability of the roofing sheet?”
“Is the roofing sheet suitable for the existing roof?”
These are the two points!

For example, if the roofing material is Super Galtect (with a durability of about 35 years) and you use regular asphalt roofing (with a durability of about 10 years), there will be a significant difference in durability between the roofing material and the roofing sheet.
Even if you use a highly durable roofing material, there may be leaks before the expected durability period, so caution is necessary.
A suitable roofing sheet for the existing roof means, for example, if the existing roofing material is “Colonial NEO” or “Pamil”, which are fragile slates, you need to use a self-adhesive roofing sheet specifically designed for cover methods, such as Tajima Roofing/Tadis Self Cover.
Therefore, identifying the existing roofing material during the on-site survey is essential!

There are many types of underlayment materials, each with different durability.
Since there are various types, such as heat-insulating roofing sheets, make sure to check if the roofing sheet being used meets your needs!

Additionally, if you are using a self-adhesive roofing sheet and there is a lot of moss on the existing roof, the self-adhesive roofing sheet may not adhere properly.
If the dirt is severe, it is necessary to perform high-pressure washing.

Make sure to check if high-pressure washing is included and the additional costs if high-pressure washing is required!

3. Flashing (valley flashing, decorative flashing, eaves flashing, waste board flashing, etc.)

There are two points to check regarding flashing!
“Is the manufacturer’s genuine flashing being used?”
“Is the decorative flashing of the setback type being used?”

If genuine flashing from the manufacturer is not used, there may be differences in durability, and in case of an emergency, the manufacturer’s warranty may not apply.
Many contractors use aftermarket flashing to reduce costs, so be sure to check!

The roof overlay (cover method) may cause the roof to be higher than the existing state, which can lead to rainwater overflowing the rain gutter.
Therefore, by using setback type ornamental patterns, rainwater can be properly directed into the rain gutter.
If you are not replacing the rain gutter, be sure to check whether a setback type ornamental pattern is being used!

4. Roof Installation

This section involves the installation of the main roofing material!
What you should check in this section is the roofing material’s “fasteners”!
Fasteners can be nails or screws, and they come in different materials, either iron or stainless steel.
While stainless steel screws are more expensive, they offer better wind resistance.

For buildings located near the sea or on elevated ground, we recommend using screws for better wind resistance!

If there is no mention of fasteners, confirm what type will be used,
“Are the fasteners suitable for the needs?”
“What are the additional costs if the fasteners are changed?”
Make sure to check thoroughly!

Aiji Industry is the manufacturer of Super Galtect.
The screws for renovations are made of stainless steel and are specifically designed for the overlay method.
It’s reassuring that they are from the same manufacturer as the roofing material!

5. Snow Guards

Make sure to check whether genuine manufacturer snow guards are being used!
Using aftermarket snow guards could lead to leaks and may void the warranty, so caution is necessary!

6. Ridge Underlayment (Nail Board)

The ridge underlayment serves as the base for the ridge metal! It is often referred to as a nail board.
This is also a critical item to check carefully just like the underlayment!
There are various types of ridge underlayment, including “wood,” “plastic,” and “metal,” each with different durability lifespans.
We generally recommend using a ridge underlayment that matches the durability lifespan of the new roofing material.

The above photos show wooden and resin-based purlins.
The durability of the purlins is as follows.

For example, if you use wooden purlins (durability approximately 10 years) with Super Galtect (durability approximately 35 years) roofing material, you will eventually need to replace only the purlins.
Since the condition of the purlins cannot be checked from the outside, it may lead to unnoticed corrosion and problems such as the purlin flashing blowing away.
The durability of resin-based purlins is also about 20 years, which does not match the durability of Galtect.
Heat deformation and cracking are also disadvantages of resin-based purlins.

In the case of Super Galtect, if the purlins are made of galvalume steel, their durability will be equivalent, and unlike wood or resin, they will not crack, providing high wind resistance and are highly recommended!

Be sure to confirm what material is used for the purlins!

7. Installation of Purlin Flashing and Rain Stop Flashing

What you should check here is the “fasteners” and “flashing (sealer)” for the purlin flashing!

First, for the fasteners of the purlin flashing, there are nails and screws with waterproof washers. If you use nails, they may come loose, and the holding power is low, which can lead to the purlin flashing coming off, so be sure to check that the fasteners used are “screws with waterproof washers”.
Also, since this is an area exposed to the outside, be sure to check whether the material is “stainless steel”!

A face plate is a type of packing used to prevent rainwater from entering at the ridge.
Since it is not visible from the outside, many contractors do not install it.
If the item “face plate” is not listed, let’s confirm whether it will be installed!

8. Sealing Material

Both the roof overlay (cover method) and the re-roofing work require waterproofing with sealing at the rain stop and ridge parts.
The necessary confirmation for this item is the type of sealing material.
Sealing materials have a lifespan, ranging from about 8 years to 30 years.
If this sealing material deteriorates, it often leads to leaks, so it is best to use high-durability materials!
Since the number of sealing locations on the roof is not that many, using high-durability sealing does not result in a significant cost difference, so we recommend using high-durability sealing.

As shown in the table above, the difference in lifespan between general sealing materials and high-durability sealing materials is significant!

Here is the price list for roof overlay (cover method) work!

3. Comparison Points for the Estimate Items of Roof Re-roofing Work Comparison Points

Roof re-roofing work involves dismantling the existing roofing materials and installing a new roof.
The difference from the overlay method is that the existing roof will be dismantled.

1. Roof Dismantling

The existing roofing materials such as tiles and slates will be stripped and dismantled.
The disposal costs of the roofing materials vary depending on the type of existing roofing materials and the presence of asbestos.
Arranging the disposal costs of roofing materials from highest to lowest is as follows:

Low Metal Roof <　Slate Roof (Without Asbestos) <　Tile Roof <　Asbestos-containing Roofing Materials High

2. Substrate Adjustment

The situation of the underlying structure may vary, but in buildings that are relatively new or have tile roofs, there is often a “distortion of the underlying structure” present.
If new roofing materials are installed without addressing the underlying distortion, the distortion will also affect the new roofing materials, making adjustments to the underlying structure necessary.

3. New Underlying Structure Installation (Roof Sheathing)

This involves installing new roof sheathing across the entire roof after dismantling and cleaning the existing roof.
In cases where the existing roofing material is slate or the building is relatively new, this step may not be necessary.
However, if the building is older or has a tile roof, this step is often required.
If it is difficult to determine the condition of the underlying structure during the estimation phase, one option is to check the existing structure after dismantling the roofing materials to make a judgment.

The subsequent processes will be the same as steps 2 to 8 of the roof overlay (cover method).

Check the price list for roof replacement work here!

Summary

There are six key points to pay special attention to when estimating roof renovations.

By referring to the items introduced this time, it will become easier to distinguish between reputable contractors and those that are not, so please give it a try!

Additionally, roof painting, overlay methods, and replacements each have their own advantages, so there may be cases where considering the long-term perspective is more cost-effective. Let’s carefully consider our options.

The important thing is to always obtain multiple estimates and never decide based solely on price!

For roof renovation estimates in Kawasaki City, contact Kakeru Koumuten

Kakeru Koumuten Co., Ltd. offers free estimates and inspections!
We have received many requests for roofing work within Kawasaki City and have a wealth of experience!
We are happy to assist with inquiries for estimates only.
If you have any concerns regarding roofs, rain gutters, exterior walls, or exteriors, please consult Kakeru Koumuten Co., Ltd.!

Kakeru Koumuten Co., Ltd. is a remodeling company strong in exterior renovations, and we carry out everything from temporary scaffolding construction to roof work and exterior painting completely in-house.
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!
We offer comprehensive construction guarantees and aftercare maintenance, and we have received positive feedback for our appropriate proposals that align with cost performance and our customers’ future life plans!

We want you to think, “I’m glad I asked them!” Therefore, we take every request we receive seriously.

We also have information on roofing costs and pricing plans for the roof overlay (cover method), so please take a look if you are interested!

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

Service Areas

Kakeru Koumuten Co., Ltd. can serve not only within Kawasaki City but also almost all areas of Kanagawa Prefecture and Tokyo.

For helpful information about exterior renovations, click here!

LINE consultations are also very welcome◎

For roofing, guttering, and exterior work and repairs in Kanagawa, contact Kakerukoumuten Co., Ltd..

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!