What is the Provision of Quality Housing Stock Association?

The Provision of Quality Housing Stock Association was established in July 2008 by nine housing manufacturers, aiming at revitalizing the circulation of Quality Housing Stock and forming a well organized housing resale market. The Association created a definition of "Quality Housing Stock" that is accepted by all participating members, and has coined a term to describe such Quality Housing Stock that satisfies all the established requirements, namely, "SumStock."
In addition, the Association has established a "SumStock assessment method" that is adopted by all participating members. Assessors who have been trained and certified by the Association, that is, SumStock-certified house sales professionals, started to use the "SumStock assessment method" to assess used residential houses.
Since the creation of the Association we have trained SumStock-certified house sales professionals, assessed
SumStock houses, promoted the circulation of the houses, and conducted PR activities to market those houses, with the goal of offering as many such houses as possible.
Another housing manufacturer joined the Association in February 2010. The Association is currently operated and managed by ten member companies.

A SumStock house is

A Quality Housing Stock that is certified by the Provision of Quality Housing Stock Association
A detached house that will offer long-term durability if properly maintained
Three requirements for SumStock certification
・The housing history data is available.
・A 50-year or more maintenance program is in place, and the house has been maintained according to that program.
・It has an earthquake resistance as specified under the new seismic code (enforced in 1981).

Background to SumStock Creation = Provision of Quality Housing Stock Association

◆Value of detached houses in Japan

Japanese houses have been constructed based on a concept of scrap and build. A housing shortage after the Second World War emphasized quantity over quality. For this reason, the concept of durable houses was not adopted in Japan at that time. As a result, the mean age of Japanese houses when demolished is much lower than in the USA or UK. (See Graph ①)
In Japan, it had been thought that the value of a house should be depreciated over about 20 years. (See Graph ②) Accordingly, in the circulation of used houses in Japan , it had always been assumed that the value of the land should was the primary consideration and the building was only an afterthought. Real estate was traded as a set of the land value and building value. Even though the construction of longer-life houses has been promoted from a standpoint of global environment conservation, society has failed to recognize the value of a good used house. Under a SumStock assessment, the value of the building and the land are indicated separately. The structural members required to give the house its strength (skeleton), and the interior finishings and facilities (infill) are assessed separately to correctly evaluate the value of the extended-life skeleton.

SumStock brand mark

A property, which is certified as a "Quality Housing Stock" by the Provision of Quality Housing Stock Association, is uniformly termed "SumStock." Affiliated real estate companies who are members of the Association promote the proliferation of SumStock houses in their distribution businesses.

優良ストック住宅推進協議会 [Brand name: SumStock]
SUM (Latin): to be, exist, continue, present, and live
SUMMA (Latin): Integrated whole (total), main point, and top status
SUMMUS (Latin): Best and top
STOCK (English/German/French): "COMMON STOCK"= Common asset of society
"Sumu" in Japanese means "live" in English
◎The name, logo and symbol mark of "SumStock" are registered trademarks. The Provision of Quality Housing Stock Association prohibits the unauthorized use of these trademarks.
Registered trademark "Registration No. 5215453"
Contact the secretariat of the Provision of Quality Housing Stock Association for permission to use the trademark, logo, symbol mark, catch phrase, slogan, copyrighted designs, and other characteristic brands.

Method of SumStock assessment

  1. For the purposes of assessment, a house is regarded as consisting of those parts required for structural resistance (hereinafter called the "skeleton") and the interior finishings and facilities (hereinafter called "infill").
  2. The house is assessed assuming that the skeleton of structural frame accounts for 60% of the entire structure and is amortized over 50 years.
  3. The house is assessed, assuming that the infill of interior finishings and facilities accounts for 40% of the entire structure and is amortized over 15 years.

The value, which is calculated based on the above three appraisals, is adjusted to the housing history data in the system of inspection and repair. A person who has completed the Association’s training curriculum, or a person that has the same knowledge regarding assessment and the same experience in assessment as a person who has taken the relevant courses, shall assess the value of the building.

Formula for SumStock assessment

Assessed value={A1×B1+(A2×B2×F+G)} ×C×D×E×H1×H2×I−J

A=Re-procurement cost
(A1 and A2)
Cost of rebuilding the house being assessed (Acquisition cost × multiple factor). A1=Skeleton (structural frame) accounts for 60% of the acquisition cost, and A2=Infill accounts for 40%.
B=Present value factor
(B1 and B2)
Present value based on circulation life years*. B1: 50 years for skeleton. B2: 15 years for infill.
* "Circulation life years" refers to the years of the house’s value in the circulation market.
C=Function adjustment factor Correction factor including assessments of "① Storage," "② Ventilation," "③ Daylighting," and "Functionality"
D=Variable correction factor Correction factor including assessment of room layout variability
E=Exterior correction factor Assessment of not only building but also external space including exterior
F=Observation correction factor Assessment of maintenance and management of interior finishings and facilities from the standpoint of purchaser
G=Remodelling addition Addition of amount based on method specified for a property whose infill was remodeled within the last 15 years
* The amount is added to the value after observational correction of the infill part.
H1=Building marketability ratio ① Assessment in consideration of social and regional needs at time of selling
H2=Building marketability ratio ② Correction factor for assessment of presence or absence of housing history document
I=Building age adjustment factor Special correction factor based on general trade situations for house for sale within 5 years after construction
J=Maintenance adjustment Adjustment for deducting an amortized amount in consideration of durable number of years of exterior-wall painting, roof and veranda waterproofing, and termite prevention
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