Basic Policy

Sumitomo Forestry believes that popularizing high-quality, durable houses as social assets plays an important role in creating a prosperous society. Based on this belief, and taking the opportunity of the enforcement of the Excellent Long-Term Housing Promotion Act in Japan in June 2009, the Company formulated a basic policy for product safety and quality control in its housing and construction business in fiscal 2009.

Basic Policy for Product Safety and Quality Control in the Housing and Construction Business

  • Make houses more reliable by improving their basic functions
  • Increase future options for layout to accommodate changes in lifestyles
  • Enhance maintenance programs to support long-term upkeep
  • Monitor information on any production faults, and share information on handling faults promptly

Sumitomo Forestry offers homes that integrate seismic resistance, durability, better insulation efficiency, Net Zero Energy Houses (ZEHs), the promotion of universal design, and easy upkeep to improve all aspects of home performance so as to offer customers homes where they can live in peace of mind and comfort for many years to come.

Design Performance Evaluation

The Company is actively promoting the use of the Japanese Housing Performance Indication System*1 for customer peace of mind and safety as well as enhancing the value of property. In fiscal 2019, under the Japanese Housing Performance Indication System, implementation rate*2 of Design Performance Evaluation reached 99.1%, Implementation of Construction Performance Evaluation reached 98.8%, and the acquisition of Excellent Long-Term Housing certification reached 94.4%.

*1 Third-party evaluation system for design performance at the time of design and of construction performance upon completion so that customers can objectively assess the quality and performance of a house.

*2 The ratio of the number of applications against the total number of detached houses constructed, including extensions and/or alterations (applications for design and construction performance evaluation, April 1, 2019 - March 31, 2020) in the Housing and Construction Division.

Japanese Housing Performance Indication System Implementation Rate

FY2015 FY2016 FY2017 FY2018 FY2019
Design Performance Evaluation 98.6% 98.8% 98.9% 99.0% 99.1%
Construction Performance Evaluation 97.3% 97.8% 97.9% 98.4% 98.8%

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Certified Excellent Long-Term Housing

Sumitomo Forestry sets the standard specifications for its Sumitomo Forestry Home houses to exceed the highest level of Excellent Long-Term Housing*1 certification conditions*2 (applying the evaluation under the Japanese Housing Performance Indication System). From product development through to construction and after-service, the Company has established its framework for product safety and quality control in order to deliver high quality homes with superior overall balance.

*1 A life-long housing certification system of Ministry of Land, Infrastructure, Transport and Tourism which aims to popularize housing that will help realize a society that values its housing stock.

*2 Detached housing is evaluated for durability, seismic resistance, ease of maintenance and energy efficiency in accordance with the Japanese Housing Performance Indication System.

Ratio of Houses Certified As Excellent Long-Term Housing for New Custom-Built Housing

FY2015 FY2016 FY2017 FY2018 FY2019
Ratio of houses certified as Excellent Long-term Housing for new custom-built housing 92.7% 93.3% 93.3% 93.8% 94.4%

Excellent Long-Term Housing Standards and Standard Performance of Sumitomo Forestry Home Houses

Certification Type Certification Criterion Standard Performance of Sumitomo Forestry Home Houses
Durability Long lasting Rating measures for deterioration class 3
Measures to allow regular inspection
Equivalent to highest level 3
Seismic Resistance Strong to earthquakes Rating of earthquake resistance 2 or higher Equivalent to highest level 3
Maintenance Requirement Easy maintenance home Rating measures for maintenance level 3 Equivalent to highest level 3
Energy-saving performance Energy-saving house House Rating measures for energy conservation level 4 Equivalent to highest level 4

* The higher the rated level, the better evaluated.

Framework for Product Safety and Quality Control

  • Undertaking development such as new technology, materials, housing products and lifestyle proposals based on consumer needs and owner surveys.
  • The Housing and Construction Division and Tsukuba Research Institute are collaborating in experiments at validation facilities and testing of prototypes, promoting the creation of products that incorporate customer feedback, including even in the details of guarantees.

Product Development

A dedicated designer responsible for the work

A dedicated designer responsible for the work

  • Sumitomo Forestry uses a unique system to check design and structure at the time of contracting and through the final design stage.


  • The Materials Selection Subcommittee, which meets once every month to decide upon all materials, conducts design reviews. All materials are checked to ensure that they meet the acceptance and quality standards set by the Tsukuba Research Institute and the Materials Selection Subcommittee.
  • After approved by the Materials Selection Subcommittee, materials are subjected to a further design review after actual on-site use (approximately two years later) to confirm whether the planned quantity can be shipped and whether or not there are any quality defects.

Materials Procurement

Construction Management

Construction Management

  • Sumitomo Forestry centrally manages and shares up-to-date information on the construction, process management, quality control and safety management of each building through its own site management system.
  • Each on-site operator, contractor manager and construction manager during such stages as foundation, construction and completion, conducts inspections which are managed using a construction management record. Additionally, the Head Office inspection division checks the status of the inspection and management.


Regular inspection

Regular inspection

  • Sumitomo Forestry includes 30 years of free regular inspections with its homes. After the first 30-years, Sumitomo Forestry provides paid maintenance constructions according to maintenance plans and, if customers extend the building warranty every 10 years, these free regular inspections continue for up to 60 years to ensure the long life of these valuable homes.
  • Sumitomo Forestry has developed a 60-year Maintenance Program that offers renovation and maintenance proposals and manages maintenance records in order to support its customers.

After-Sales Support


  • The performance and reliability of Sumitomo Forestry's proprietary materials used in anti-seismic reinforcement and so on are verified at the Tsukuba Research Institute. In addition, we are advocating seismic retrofitting by undergoing a technological evaluation of the Japan Building Disaster Prevention Association.

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Seismic Resistant Housing

The Great Hanshin-Awaji Earthquake and the Great East Japan Earthquake as well as a recent major earthquake in Kumamoto have been among the disasters that have wrought enormous damage in Japan. In addition, major earthquakes are forecast to occur in the Nankai Trough, resulting in year-by-year increase in demand for seismic resistance for wooden houses.

In response to customer need for seismic resistant houses, Sumitomo Forestry Home Tech has developed original construction methods that enable heightened seismic resistance without diminishing high levels of the home's structural strength, workability or insulation efficiency.

Development of K-type Corner Braces and RGS Panels

K-shaped corner brace bearing walls use 24 mm thick structural plywood that is in order to store 75 mm thick glass-wool insulation inside. This method has great workability because the materials are light, and it underwent a technological evaluation by the Japan Building Disaster Prevention Association (6.0KN/m² standard bearing wall).

GS panels for renovation (RGS panels) are used as a seismic resistance method to limit deformation by installing these right and left panels (structural plywood with a 24 mm thickness) made of special metals sandwiching highly rigid and highly damping rubber in vertical members. Even greater workability is provided by dividing these panels into top and bottom pieces as well. The method underwent a technological evaluation by the Japan Building Disaster Prevention Association (6.1KN/m² bearing wall).

Moving forward, we plan to develop new vibration dampers that can reduce earthquake damage to buildings to the greatest possible extent.

RGS Panel

RGS Panel

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BF Method

Sumitomo Forestry started selling the Big-Frame Construction Method (BF Method) as a product for three-story building products in February 2005 and expanded this method to two-story products in October 2009 as well as to products with fire-resistant specifications in four-story buildings in April 2015. Thereafter, as awareness of customers grew about risks such as disasters, the BF Method that had further evolved to provide greater strength in high seismic resistance matched customer needs and is now one of Sumitomo Forestry's main products.

The proprietary BF Method from Sumitomo Forestry is the first in Japan to realize the wooden beam Rahmen structure, which is used in high-rise buildings, in wooden houses.

The Rahmen structure is designed to stand up to horizontal forces such as earthquakes and wind through rigid-joints that unify the columns and beams with the fixings. The BF Method uses big columns with a large cross-section of 560 mm which is equivalent to roughly five standard 105 mm columns and incorporates structural materials in addition to a combination of metal-to-metal joints to achieve a robust Rahmen structure.

The beams and bases of the big columns join strongly thanks to the metal-to-metal joints. This brings about horizontal vibration resistance equal to a 22.4 (times/meter) shear resistance of walls. We ensure seismic resistance while being able to provide both large spaces and wide openings.

In addition, expanding and introducing a variety of original technology can support an even wider range of design requirements. Twin-bolt columns (shear resistance of walls equivalent to 33.6 times/meter) that doubles metal joints as well as double-large columns that layer two large columns (shear resistance of walls equivalent to 44.8 times/meter) provide freedom in floor plans and more spaciousness even on land with many restrictions. The pre-stressed timber beams are large-span beams enable the design for built-in garages ready for parking multiple vehicles, large open living rooms, multi-dwelling homes in addition to a wide range of other purposes.

Sumitomo Forestry conducts vibration tests on verification models of structural framework, using the BF Method as well as full-scale structures to examine seismic resistance in anticipation of a large-scale earthquake.

The full-size verification model for a three-story building constructed with the BF Method cleared testing for vibrations of a maximum acceleration of 2,699 gal, which is equivalent to the Great East Japan Earthquake (3.3 times the Great Hanshin-Awaji Earthquake). Our technology has been proven tough through a total of 22 harsh vibration tests; two of which were conducted at a magnitude of 7 equal to the Great East Japan Earthquake and 20 of which at a magnitude of 7 equal to the Great Hanshin-Awaji Earthquake. We also estimate strong aftershocks after a massive earthquake by implementing a repetition of a total of 246 vibration tests. We have repeatedly conducted testing with strong vibrations from a magnitude of 4 to a magnitude of a weak 6 and beyond to magnitude of 7 to ensure continued seismic resistance of the structural framework.

In this way, the BF method responds to the needs of customers with powerful structures to bring security as well as flexible designs able to provide comfortably spacious spaces.

Strong Big Column with a Width More Than Five Times a Standard Pillar

Strong Big Column with a Width More Than Five Times a Standard Pillar

Realizing a Robust Rahmen Structure via Metal-to-Metal Joints

Realizing a Robust Rahmen Structure via Metal-to-Metal Joints

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Promotion of Universal Design

Sumitomo Forestry is a pioneer in establishing soft closers for all indoor furnishings such as sliding doors and hinged doors as an initiative to increase the safety of residents. In addition, an all flat design that does not create any level differences in flooring is now a standard specification while convex corners for inner walls and wall-mounted convex sections have an R-shape specification around living spaces and halls. We have set the standard specifications for the width of hallways to 780 mm to allow the use of assistive wheelchairs with the assumption that wheelchairs and care will be necessary in the future. We also flexibly respond to customer requirements through a freedom in design that includes slopes to entrances and the installation of home elevators.

Furthermore, Sumitomo Forestry is placing its strength in the design of living spaces to satisfy the needs of customers such as development of stairs with enhanced visibility, heat shocks, and the Air-Dream Hybrid total air conditioning system that reduces house dust and realizes a comfortable space without any temperature fluctuations. Sumitomo Forestry also provides comfortable bedroom environments with original wooden interiors that have indirect lighting to offer better sleep quality and reduce fatigue in indoor environments perfect for sleeping.

Stairs provide enhanced step visibility.Received KIDS DESIGN AWARD in FY2010

Stairs provide enhanced step visibility.
Received KIDS DESIGN AWARD in FY2010

These stairs provide safety-type resin-joint steps with greater visibility than standard stairs.Received KIDS DESIGN AWARD in FY2012

These stairs provide safety-type resin-joint steps with greater visibility than standard stairs.
Received KIDS DESIGN AWARD in FY2012

Indirect lighting of wood offers better sleep quality and reduces fatigue.
Received KIDS DESIGN AWARD in FY2016 (Survey and Research Category)

Indirect lighting of wood offers better sleep quality and reduces fatigue.
Received KIDS DESIGN AWARD in FY2016 (Survey and Research Category)

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Sustainability Report