Safety and Quality of Products and Services
Product Safety and Quality Management in the Housing and Construction Business
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 Act on the Promotion of Long-life Quality Housing 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.
Product Safety and Quality Management in the Housing and Construction Business
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 2021, under the Japanese Housing Performance Indication System, implementation rate*2 of Design Performance Evaluation reached 99.5%, Implementation of Construction Performance Evaluation reached 99.3%, and the acquisition of Long-life Quality Housing Certification reached 94.9%.
*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, January 01, 2021 - December 31, 2021) in the Housing and Construction Division
Japanese Housing Performance Indication System Implementation Rate*
|Design Performance Evaluation||99.0%||99.1%||99.4%||99.5%|
|Construction Performance Evaluation||98.4%||98.8%||99.3%||99.3%|
* The aggregation period for fiscal 2020 onwards is January to December of each year, and the aggregation period before fiscal 2019 is April of each year to March of the following year.
Long-life Quality Housing Certification
Sumitomo Forestry sets the standard specifications for its Sumitomo Forestry Homes to exceed the highest level of Long-life Quality 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 Long-life Quality Housing for New Custom-Built Housing*
|Ratio of Houses Certified As Long-life Quality Housing for New Custom-Built Housing||93.8%||94.4%||94.7%||94.9%|
* The aggregation period for fiscal 2020 is April to December of each year, and the aggregation period before fiscal 2019 is April of each year to March of the following year.
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 class3||Equivalent to highest level 3|
|Measures to allow regular inspection|
|Seismic Resistance||Strong to earthquake||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 conservation performance||The house must be thermally insulated||Rating measures for energy-saving performance 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 guarantee
- 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.
- 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.
- 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.
- 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.
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, such as installation into existing floors and ceilings without any removal and disposal.
Development of K-shaped Corner Braces and Hyper 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).
Hyper Panels reduce removal work by only having to remove the gypsum board between existing flooring and ceilings. Hyper Hard T (Yoshino Gypsum Co., Ltd.) improves workability by dividing a high-strength board into three pieces for installation so that each board can be put in place as is. Three pieces of the board for installation enhances the bending strength without the board breaking. The method also got a technological evaluation by the Japan Building Disaster Prevention Association (6.9 KN/m2 bearing wall for the standard type).
Moving forward, we plan to develop new vibration dampers that can reduce earthquake damage to buildings to the greatest possible extent.
Construction Method (BF Construction Method)
Sumitomo Forestry started selling the Big-Frame Construction Method (BF Construction 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 construction 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 construction 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 construction 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 construction 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 construction 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 construction method responds to the needs of customers with powerful structures to bring security as well as ﬂexible designs able to provide comfortably spacious spaces.
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.
In addition, anti-virus requirements are utilized for the handrails at the entrance, stairs, and toilets, which are frequently handled on a regular basis, and antibacterial specifications are used for coping in front of the kitchen near cooking area.
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.