Kakeru Koumuten Co., Ltd. | What is the Cost Range for Roof Renovation? Types of Work, Fire Insurance, How to Choose a Contractor, and More

Hello!
This is Yamanaka from Kakeru Koumuten Co., Ltd., a specialist in exterior renovations located in Aoba-ku, Yokohama, Kanagawa Prefecture!
What is the cost range for roof renovations? We explain the types of work, fire insurance, and how to choose a contractor!
The roof, which protects against rain and ultraviolet rays, is an important part of a home, but it’s often difficult to understand its condition. When roof renovations or repairs become necessary, many people may worry about how much it will cost.

In this article, we will explain the cost range for roof renovations, the appropriate timing for the work, and how to choose a renovation contractor. We also discuss fire insurance and other related topics. If you are considering a roof renovation, please read this article thoroughly before requesting work.

About Roof Renovation Prices and Cost Ranges

The total cost of roof renovations for an average-sized home is as follows:
● Tile roof: Approximately 600,000 to 1,500,000 yen
● Slate roof: Approximately 450,000 to 1,200,000 yen

Let’s take a look at the cost ranges for different types of roof renovation work.

○ Existing roof: Color best, slate, colonial

○ New roofing materials
・Color best (such as Colonial Quad) and shingle materials (Asahi Fiberglass/Ridgeway, etc.)

Ridgeway Color

■Dual Black

■Harvard Slate

■Dual Brown

■Vintage Green

■Earthstone Cedar

●5000〜7000 yen/㎡

・Galvalume steel roofing materials (Inagaki Shouji/Hiranbi, etc.)
●5500〜7500 yen/㎡

・Galvalume steel roofing materials with insulation (Aiji Industry/Super Galtect, Yokodana Roof, etc.)

Super Galtect Colors

■Shade Black

■Shade Brown

■Shade Moss Green

■Shade Blue

■Shade Charcoal

●7000〜9000 yen/㎡

・Zinc-aluminum steel plate (D-Trade/ Eco Grani, etc.)

Eco Grani Color

■TWEED GRAY

■CAFE

■EVER GREEN

■ONYX

●7000〜9000 yen/㎡

【Roof Replacement Work】
＊Work Details
1. Demolition and cleaning of existing roof
2. Installation of new sheathing (substrate)
3. Installation of new waterproofing paper (roofing)
4. Processing and installation of new metal flashings (decorative and eaves)
5. Installation of new roofing materials and snow guards
6. Processing and installation of ridge flashings
7. Processing and installation of wall rain diverter flashings

○Existing Roof: Japanese tiles, Western tiles, color best, corrugated metal

○New Roofing Materials
・Color best (Colonial Quad, etc.) and shingle materials (Asahi Fiberglass/Ridgeway, etc.)
●8000〜14500 yen/㎡
・Galvalume steel roofing materials (Inagaki Shouji/Stanby, Hiranbi, etc.)
●8500〜15000 yen/㎡
・Galvalume steel roofing materials with insulation (Aiji Industry/Super Galtect, Yokodana Roof, etc.)
●9500〜16000 yen/㎡
・Zincalume steel (D Trading/Eco Grani, etc.)
●9500〜16000 yen/㎡

【Upgrading the Roofing for Overlay and Replacement】
The standard is asphalt roofing (durability 10 years).
・Modified asphalt roofing
●300 yen〜600 yen/㎡ (durability 20〜60 years)
・Self-adhesive roofing (durability about 20 years)
●350 yen〜450 yen/㎡

【Tile and Slate Replacement Work】
●5000〜20000 yen
Work to replace broken tiles or slates with new ones

[Roof Ridge Cap Replacement]
*Construction Details
1. Removal of existing ridge cap and purlins
2. Installation of new purlins
3. Processing and installation of new ridge cap
● Galvalume steel sheets and metal sheets: 3,000 yen to 6,000 yen/m
● Purlin replacement only is also possible: 1,500 to 3,000 yen/m

[Repointing Work]
● Approximately 2,500 to 3,500 yen/m for one side

[Caulking Repair Work]
● Starting from about 5,000 yen per location
For chips or peeling of slate roofs, or holes in metal roofs

[Common Construction Costs]
● Scaffolding cost: 600 yen/m² (including protective sheets)
● Roof scaffolding cost: 700 yen/m²
● Asbestos treatment cost (for old slate roofs): 5,000 yen/m²

The actual construction cost for roof replacement and roof overlay (cover method) renovations varies depending on factors such as the type of existing roofing material and new roofing material, the shape of the roof, the number and scope of construction areas, and the contractor’s region. For the final total cost, it is advisable to have a local contractor conduct an on-site inspection and provide a quote.

To avoid future troubles, it is important to ask questions and confirm any unclear points until you fully understand.

Differences Between Roof Replacement and Roof Overlay (Cover Method) Work

Roof replacement work involves dismantling the existing roof and then constructing a new base and roof.
Due to the costs of waste materials and dismantling, this method tends to be expensive.
Roof overlay work involves installing a new roof over the existing roof.
Since there are no costs for waste materials and dismantling, it helps to reduce costs. Additionally, the roof becomes thicker, improving insulation.
However, depending on the existing roofing material, overlaying may not be possible (such as with tiles or battened metal sheets).
At our company, slate, shingle materials, color best, and colonial roofs are mostly done with overlay work.

Useful Tips for Roof Renovation

Why is Galvalume Steel Popular for Roof Renovations?

In recent years, “Galvalume steel,” which is a thin metal sheet coated to resist rust, has gained attention among roofing materials. Despite being a metal sheet, it is lightweight and relatively inexpensive, making it widely adopted as roofing material, including for roof renovations.

Depending on the environment, the lifespan of typical roofing slate is around 10 to 25 years, while Galvalume steel is said to last up to 40 to 50 years, with manufacturer warranties of up to 25 years, which is a significant attraction due to its durability.
However, the steel sheet alone does not have high insulation performance, and rain noise may be a concern inside the house, so it is necessary to install insulation or sound-absorbing materials as a countermeasure. Recently, integrated insulation Galvalume steel sheets (such as those from Aijii Industry/Super Galtect) have also been widely adopted. It is our most popular roofing material.

What is Zincalume Steel?

Zincalume steel is often referred to as roofing material that has natural stone granules sprayed onto a material almost identical to Galvalume steel.
Zincalume and “Galvalume” are actually composed of almost the same materials: aluminum (55%), molten zinc (43.4 to 43.5%), and silicon (1.5 to 1.6%).
There is a tendency to differentiate based on whether it is domestically produced or imported.
Additionally, this stone granule-coated steel sheet (such as those from D-Trading/Eco-Grani) is known for its superior durability compared to standard (non-stone granule) Galvalume steel, with manufacturer warranties of up to 30 years being a significant feature.

When Should You Consider Roof Renovation?

There are suitable timings and recommended periods for roof renovations.
Timing for Roof Renovation
The timing for roof renovation varies depending on the type of roofing material. The general maintenance periods and guidelines for different roofing materials are as follows:
● Slate Roof: 10–25 years (if asbestos-free)
● Japanese Tile: 40–50 years
● Cement Tile: 15–25 years
● Galvalume Steel: 40–50 years
● Tin Roof: 10–20 years

It is advisable to consider renovations or repairs based on the above periods.

Additionally, here are some points to consider when contemplating a roof renovation:
● Water stains or discoloration on the ceiling, moss
● Water stains, lifting, or misalignment on the roof
● Cracks or damage to the roofing material
● Age of the building is over 15 years

Regardless of the type of roofing material, it is generally advisable to consider a renovation about 15 years after installation.

Recommended Timing for Roof Renovation

The ideal times for roof renovation are November to December and March to May, when there is no impact from rain and wind. Since the work involves heavy labor such as transporting roofing materials and climbing scaffolding, efficiency may decrease during the hot summer months.

The duration of roof renovation work varies depending on the area to be repaired, the type of roofing material, and the number of workers, but it typically takes about 4 days to 2 weeks. However, since it is affected by weather conditions, if it coincides with a rainy season, the construction period may be extended, so it is important to discuss the schedule with the contractor.

Can Fire Insurance Be Applied to Roof Renovation?

In some cases, fire insurance can be applied to roof renovation work.

For example, repairs may be necessary in the following areas:
● Damage to tiles or plaster
● Lifting or detachment of ridge cap
● Leaks from the roof
● Damage to rain gutters
● Balconies, etc.

In the case of roofs, if there is lifting of the ridge cap, there may be a possibility of damage due to typhoons or strong winds, which could qualify for fire insurance coverage. Similarly, leaks caused by damage to rain gutters or the roof may also be included.

However, fire insurance does not apply in all cases, and it will be determined by an assessment from a third-party organization. The average insurance payout when fire insurance is applicable is estimated to be between 400,000 to 700,000 yen, but this varies depending on the insurance company and coverage details.

To apply for fire insurance, it is advisable to first consult with a professional to confirm the necessary documents and procedures. Since fire insurance is something you pay for but may not have the opportunity to use often, it is recommended to utilize it effectively.

How to Choose a Contractor for Roof Renovation

Choosing a contractor is also important when requesting a roof renovation. Roofing contractors include large renovation companies as well as local construction firms and painting contractors, resulting in a vast number of options available online.

To find a contractor that suits your home’s specific roofing renovation needs, consider the following points:
● Ability to perform work suitable for the local climate and weather
● Willingness to reflect your requests in the work
● Providing an appropriate price estimate
● Answering questions thoroughly
● Is there a solid warranty?

If you already have a trusted construction company or renovation firm, consulting with them directly can also be effective.

If you are looking for a contractor, obtaining estimates from 2 to 3 companies can be beneficial to ensure you choose the right one. If the costs are extremely low or high, there may be underlying issues, so be cautious and request detailed estimates.

There are also websites where you can input necessary information such as the size of your home, address, and age, and request estimates from relevant companies all at once. However, these sites often charge a fee, which can make the overall cost higher, so they are not highly recommended.

Conclusion

Let’s consult with a contractor that has extensive experience in roof renovation projects.
Roof renovation work varies depending on the type of roofing material and the scope of repairs. The age of your home and the condition of the roof are effective factors in determining whether renovation work is necessary.

However, accurate judgment and actual construction must be entrusted to professional contractors, so it is advisable to choose a contractor based on the average costs and key points of renovation work introduced here. Our company also accepts consultations regarding roof repairs and renovations at any time, so please feel free to reach out to us.
Kakeru Koumuten Co., Ltd. handles roofing, scaffolding, and painting work entirely in-house. We promise appropriate costs, knowledge, and skills. We will not propose unnecessary work.

 

LINE consultations are also very welcome◎

 

神奈川で屋根・雨樋・外装の工事、修理なら
株式会社翔工務店へ

株式会社翔工務店は平均年齢２０代後半の若い会社ですが、技術はどこにも負けていません。

いちばんの強みは、足場工事、屋根工事、塗装工事とすべて自社で行えること。一般には分業されるこの業界にあって、一式で頼めるので管理に手間がかからず、コストも抑えることが出来ます。何より、トラブルがあればすぐにかけつけます！

自信をもって、宣言できます。私たちは、神奈川で一番若くて親切なリフォーム屋です！

 

無料お見積りはこちら