Gassho-Zukuri Styled Minka Village, Gifu, Japan - Exploring Sustainable Vernacular A4 Report

Gassho-Zukuri Styled Minka Village Gifu, Japan

DARCH/FT/3A-B/ 0102 Group 05 Coyee | Ellyxia | Genevieve | Haleemah | James | Kai Zheng

SECTION 1 / 3 01 - 04

I.

Introduction

05 - 06

II.

Site context | Location plan

07 - 12

III. Weather Data

SECTION 2 / 3 15 - 20

I.

Building history

21 - 22

II.

Site plan

23 - 24

III. Macro analysis

25 - 36

IV. Micro analysis | FLoor plans | Sections

SECTION 3 / 3 39 - 40

I.

Construction and detailing

41- 42

II.

Roof plan | Construction technique

43- 44

III. Structure | Material used

45- 46

IV. Construction sequence

47- 48 49- 50

V. Detailing and joints VI Passive strategy - thatched roof

SECTION 1 / 3 I.

Introduction

II.

Site context | Location plan

III. Weather Data

Introduction

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Introduction The subject of our studies will be based on the Gasshō-style Traditional Japanese Farmhouse. Throughout this report, we will be looking closely at the history of this region and its towns, as well as the Gassho Zukuri Styled homes and their construction.

Most prevalent in two villages in central japan — Shirakawa-go in Gifu Prefecture and Gokayama in Toyama Prefecture — The Gasshō-style farmhouse is a rare variant of japanese Minka and as such, the two villages have been preserved and designated as a World Heritage Site by UNESCO. The term minka literally means “houses of the people”, It covers houses that mainly belonged to the non-samurai castes such as farmers, fishermen, merchants etc. As such there are four different types of Minka. The Gassho Zukuri style home belongs to the Sanka group of Minkas which pertains to mountain houses.

01 | 02

Figure. Oil painting of Shirakawa-go by Kitagawa Teruo

Introduction

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

“Gassho-Zukuri” means "constructed like hands in prayer", as the farmhouses' steep thatched roofs resemble the hands of Buddhist monks pressed together in prayer. Its architectural style has been developed over many generations and was designed to withstand heavy amounts of snowfall during Japan’s cold winters, some of the dwellings have even managed to survive for more than 250 years. This is an even more impressive fact considering that these homes were built without using nails.

Figure. Buddhist monk praying

The Gasshō-style was developed to accommodate large families of multiple generations, while retaining enough space for industrial practice. As space was limited within the regions Gasshō-style homes were built, multiple floors of up to 5 or more would be constructed. The main industry of the two villages mainly involved silk-rearing and as such, the attic spaces were used to raise silkworms.

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3

Location Plan | Site Context

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Shirakawa Village , Gifu Prefecture, Japan Shirakawa is a village located in Ōno District, Gifu Prefecture, Japan. It is best known for being the site of Shirakawa-gō, a small, traditional village showcasing a building style known as gasshō-zukuri.

Shirakawa is a mountain village located in far northern Gifu Prefecture, bordering Ishikawa Prefecture and Toyama Prefecture on the Ryōhaku Mountains. Mount Hakusan is the highest elevation at 2,172 metres (7,126 ft).

The village’s area is 95.7% mountainous forests, and its steep places are characteristic. In between the mountains flows the Shō River, which continues to the north into Nanto, Toyama. Most of the population is in its river valley. Since the opening of Hida Tunnel, Shirakawa can be reached within 50 minutes from Takayama, Gifu compared to the earlier three hour drive, and only an hour to Nanto in Toyama.

Neighbouring municipalities Gifu Prefecture ● ● ● ● ● ●

Takayama Hida Toyama Prefecture Nanto Ishikawa Prefecture Hakusan

Figure. Map of Shirakawa-go

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Humidity

Dry bulb Temperature

Weather Data

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Humidity Humidity levels increase with the temperature, causing humidity levels to be the highest from June to August during summer and lower from December to February during winter.

However, an interesting thing to note is that the humidity levels are higher than that of larger cities such as Osaka and Tokyo.

This is possibly due to the fact that Gifu is located in a valley and since often streams converge and flow through the valley region. This can increase the type, variety and density of plants in the valley region.

Dry bulb Temperature Gifu prefecture, or Japan in general experiences the 4 seasons; with high temperatures from June to August during Summer and low temperatures from December to February during winter.

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Rainfall

Wind Rose

Weather Data

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Rainfall Japan experiences a varied rate of precipitation due to having 4 seasons as well as being in a temperate climate. Higher rainfall is experienced from May to July, which is during Summer and when temperatures are generally higher.

Wind Rose Japan’s wind speed is influenced mainly by the surrounding geographical topography, such as hills or typhoons. This is especially so for Gifu as the prefecture is located in a valley.

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Sunpath

Psychrometric chart

Weather Data

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Sunpath The Equinox passes further South, resulting in less light in the North faces.

Psychrometric chart The design strategies recommended by the psychrometric chart are varied, as Japan has a temperate climate and experiences the 4 seasons of weather; and different variation of weather for each season. Despite that, the design strategies cater for mostly cool weather, as at least half of the seasons have a cool temperature (Autumn, Winter).

As it is weather/climate on its own without the involvement of design strategies we get 7.9% of comfort.

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SECTION 2 / 3 I.

Building history

II.

Site plan

III. Macro analysis IV. Micro Analysis | Floor plans | Sections

Tataena-Shiki

Warehouse

Gassho Zukuri (Sanka)

Farm House (noka)

Merchant House (Machiya)

Building History

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Brief history on “Minka” Homes The Gassho Zukuri Styled home is considered a part of the Minka dwellings which means “House of the people”. Japanese Minka are typically dwellings belonging to the non-samurai castes of society and are characterised by their structure, roof shape, and type of material used in construction. Most Minka were built during the edo period, when japan was under the rule of the Tokugawa Shogunate, and the lands were at peace. During this period, it was important to own a house that is able to withstand the elements of nature, in Japan’s case, it involved typhoons, heavy snowfall, rainfall, earthquakes, etc.

Thus, in the face of all these difficulties, it was better to design homes that could be easily rebuilt, rather than withstand the elements.

Minka were designed based on very standardized measurements, practices and materials. In-fact, the design was often regulated by the authorities governing minka villages. it was important that a status quo was maintained within these villages to ensure that everyone was reminded of their correct station in life (their status within the social structure). For example, designing a home with straight beams was considered too flamboyant, as compared to curved beams.

Japanese Minka can be categorized into four groups: ● ● ● ●

Farmhouses (noka) Fishermen’s houses (gyoka) Mountain houses (sanka) Urban houses (machiya)

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Figure. Farmhouse (noka)

Figure. Fisherman house (gyoka)

Figure. Mountain house (sanka)

Figure. Urban house (machiya)

Building History

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Variations of “Minka” Homes All of the above often had regional variations depending on the local climate, and availability of materials, but some common features can still be identified among them. For instance, Urban houses make up the smallest of the four categories because of the lack of space available within cities but this problem was solved by building vertically, thus many machiya contained two floors.

Interior design also involved a mostly standardized process where-which rooms were commonly measured using tatami mats or a uniform column layout. This made it easy to measure and install screen doors, though it was much better to use tatami mats to match the size of the doors. Rooms are often given a specific purpose, some of them even sharing multiple uses based on a combination and layout of paper screens and screen doors, this was also meant to easily change the scale of the room based on the user’s configuration of the room. One example of a room which has survived until modern days is the Genkan, the japanese traditional entryway, typically made with a hardened earth floor. Visitors and tenants are required to remove their shoes before stepping into the house proper, thus the genkan was designed to keep dirt from tracking into the house.

Gassho Zukuri style homes, belong to the sanka group and are prevalent in the northern part of Gifu Prefecture in central Honshu, they are easily recognizable by their roof form. The name “Gassho Zukuri” meaning “the style of a steep-rafter-roof mimicking the joining-of-hand-in-prayer” refers to the vast steep roofs constructed with thatch often resembling a Buddhist monk’s hands pressed together when in prayer.

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Figure. Illustration of a typical minka house

Building History

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

House construction The GasshĹ?-style house ("prayer-hands construction" style) is characterized by a steeply slanting thatched roof, resembling two hands joined in prayer.

The design is exceptionally strong and, in combination with the unique properties of the thatching, allows the houses to withstand and shed the weight of the region's heavy snowfalls in winter.

The houses are large, with three to four storeys encompassed between the low eaves, and historically intended to house large extended families and a highly efficient space for a variety of industries. The densely forested mountains of the region still occupy 96% of all land in the area, and prior to the introduction of heavy earth-moving machinery, the narrow bands of flat lands running the length of the river valley limited the area available for agriculture and homestead development. The upper storeys of the gasshĹ? houses were usually set aside for sericulture, while the areas below the first (ground) floor were often used for the production of nitre, one of the raw materials needed for the production of gunpowder.

The Gassho-style house is architecturally one of the most important and rare types of farmhouse in Japan. The clustering of so many surviving examples has given the World Heritage Site its justification for inscription (i.e. formal recognition). This confident style of house construction is unique within Japan, and nowhere else within the country is roof space typically utilised, except for passive storage, and not in a two, three or four storey manner, as is seen here.

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Site Plan

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Site History The cultural property consists of three historic mountain villages over an area of 68 hectares (170 acres) in the remote Shogawa river valley, stretching across the border of Gifu and Toyama Prefectures in central Japan. Shirakawa-gō (白 川郷, "White River Old-District") is located in the village of Shirakawa in Gifu Prefecture. The Gokayama (五箇山, "Five Mountains") area is divided between the former villages of Kamitaira and Taira in Nanto, Toyama Prefecture.

The valley is in a mountain region with considerable snowfall, and these villages are well known for their clusters of farmhouses, constructed in the architectural style known as gasshō-zukuri (合掌造り), which are designed to easily shed snow from their roofs.

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Figure. Site plan indicating wind path, sun path and landscape of Gassho-Zukuri Styled Minka Village

Macro Analysis

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Natural Environment Shirakawa Village is a typical mountain village, surrounded by mountains. 96% of the village area is forested, while agricultural land only accounts for 0.4%.This village was designed in a complex topography terrain located between mountains and filled with large cedars and oaks.

The program, of approximately 200 sq.m in the interior —much reduced compared to the 2,660 sq. m of the land— leads to propose a project that benefits from the topography taking full advantage of the views and respecting almost all the existing trees.The design of the wood houses aims to harmonize with the landscape and the rustic atmosphere. The village also contains places such as Hakusan National Park and Amo Prefectural Nature Park, where nature has remained undisturbed for many years. Within the Hida region, villages are found in particularly rugged areas of mountain folds.

Between the steep slopes flows the Shogawa River, with settlements developing in its basin.

Wind Path In between the mountains flows the Shō River, which continues to the north into Nanto, Toyama. Although the windrose chart indicate that the prevailing wind of Gifu, Japan are from the north-east and south-west, local site studies within the Minka village indicates that the wind blows along Sho-river and goes right through the houses. This is also why all the houses are position parallel to the direction of flow of the river. Besides,. it also protects the houses from being knocked down by the strong wind.

Sun The roofs face west and east to get sunlight as much as possible. This style helps melting snow and dry the roofs quickly in a winter to make them last longer

Snowfall One of Shirakawa-go’s key climate features is that its snowfall is some of Japan’s heaviest. Snow falls from December to March, depositing around 2 to 3 m over the area (record snowfall of 4.5 m). Shirakawa-go has been geographically described as an “isolated island”, and also referred to as an “unexplored region”, not just because of the surrounding mountainous terrain, but also due to the fact that links with the surrounding areas could become blocked by snowfall.

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Figure. Various layouts of tatami mats according to the house size

Section 1 | 2 | 3

Floor Layouts | Micro Analysis Gassho-Zukuri Styled Minka Village

Design of the floor plan There were two main methods for setting out the floor plan of the minka.

The kyoma (京間) method uses a standard size of tatami (畳) mat, whereas the inakama (田舎 間) method is based upon column spacing.

The kyoma method works well for minka without central columns as the mats and the sliding partitions (fusuma (襖) and shōji (障子)) can be based on a standard size. It was mainly used in minka in eastern Japan.

The method has its disadvantages if used with posts because variations in post width can make the prefabrication of the sliding partitions difficult.

The inakama method is based upon the distance between centre of one post and centre of the post adjacent to it and it was mainly used on the eastern side of Japan.

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Section 1 | 2 | 3

1st Storey Plan | Micro Analysis Gassho-Zukuri Styled Minka Village

Floor Layout and Description The interior of a minka was generally divided into two sections: a floor of compacted earth, called a doma (ĺœ&#x;é–“) and a raised floor, called a hiroma.

Figure. Drawing of a typical guest room in a gassho-zukuri lodging

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HIROMA

DOMA

Figure. Division of spaces

Section 1 | 2 | 3

1st Storey Plan | Micro Analysis Gassho-Zukuri Styled Minka Village

Doma The Doma is an area within the minka typically built on the ground floor with packed earth for its flooring. This is where you would find the rooms closest to the entrance, as the Genkan (entranceway) is located on the same level.

The entranceway is located at the lower-end of the first floor plan, this is where guests, and tenants alike would remove their shoes before entering the house proper.

The Umaya (Stable) is located next to the entranceway, a convenient placement as they are both used as a means of entry into the house, it can even be considered as a sort of “garage”.

The Usunawa (Workshop) is where basic craft, and handiwork is carried out and the Minjya is where food is stored and the pots and cups are washed after cooking.

Hiroma The rest of the rooms (in order) located within the hiroma are the Living room (ooe), kitchen (Daidokoro), the Sericulture room (Suenodei), bedrooms (Cyouda), Spare room (Hikai no Dei) and the altar room (Dei).

The Hiroma is the area within the Minka where the living spaces are located, these rooms are typically raised from the ground floor (generally around 20 inches (50cm) above the level of the Doma) so as to prevent dirt from tracking in from the outside.

The sericulture room (Sue no Dei) is used for silk cultivation. Typically, the silkworms are raised on the upper floors using silkworm trays, the Suenodei is where the cocoons are brought for heating and unravelling.

The bedrooms are typically laid with tatami mats, for comfort, this where the residents would rest. Typically located near a hearth, so as to provide warmth for sleeping during winters. The spare room is reserved for for travelling guests, hence its name being translated as “Withdrawing room”(Hikai no Dei).

The last room, known as the Dei is reserved for art appreciation and religion. The room features a Tokonoma, an alcove used to contain important and favoured items such as bonsai or calligraphic scrolls. Next to the Tokonoma is a raised piece of floor used to display a buddhist shrine.

Typically, the Dei is used as a formal sitting room/ antechamber, honoured guests would sit with their backs to the tokonoma.

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Section 1 | 2 | 3

2nd Storey Attic Plan | Micro Analysis Gassho-Zukuri Styled Minka Village

Attic Space Traditionally, attic spaces or lofts were used for raising Silkworms or for storage and were accessed via a Japanese staircase chest (Kaidan dansu) fitted with removable drawers and a closet. In this case, the attic is accessible via a conventional staircase, and was used for silkworm raising.

Silkworm raising is done using silkworm trays (As seen in figure 2).

Figure. 1 wide shot of the silkworm cultivation process

Figure. 2 Close-up view of a silkworm tray

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17

Section A-A

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Thatched Roof Thatch is a natural product of reed, grass or heathers, when properly cut, dried, and thatched forms a waterproof roof. It is a naturally weather-resistant material and when properly maintained does not absorb a lot of water.

Thatch is also a natural insulator, and the air pockets within a straw thatch roof insulate the building in both warm and cold weather. A thatched roof will ensure that a building will be cool in summer and warm in winter.

Figure. Image of a minka thatched roof

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Section B-B

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Farmhouses have their origins in the tateana (pit houses) or heichi jĹŤkyo (flatland dwell ings) of ancient times. The floor area of the oldest type of farmhouse known today was equally divided between a dirt floor and an open raised area constructed of wood. Gradually, the percentage of the living area devoted to the raised portion was increased to provide more space for individual rooms. Until recently, however, most of the time indoors was spent on the dirt floor.

The central area of a farmhouse is known as the kamiya , which corresponds to the moya of a Buddhist temple. In old farmhouses, numerous posts were used to support the roof. The number of posts was gradually decreased by resting large weight-bearing beams upon widely spaced posts to create a basic structure, on top of which was constructed a complicated network of interlocking vertical and horizontal members, known as the koya-gumi , to support the roof. In brief, the living area beneath the main beams was simplified but the roof structure above the main beams was made more complicated. When left open, the koyagumi added to the grandeur and aesthetic appeal of the interior of a traditional farmhouse.

The largest area on the raised floor portion is the living room ( O-ie ), which is frequently bordered by peripheral rooms, also on the raised floor. From the raised floor, one steps down to the dirt floor where the kitchen and other work areas are located. Together, the combination of raised floor and earthen area developed into a simple, functional, and aesthetically pleasing style that provided a marked contrast to urban mansions with their elegant Shoin style rooms.

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SECTION 2 3/ 3 I.

Building history Construction and detailing

II.

Site Roofplan | Construction technique

III. Macro analysis Structure | Material used IV. Micro Analysissequence | Floor plans | Sections Construction V. Detailing and joints VI Passive strategy - thatched roof

SANGAI AMA

SORA AMA

AMA

Figure. Illustration showing attic and structural elements within the house

Figure. Illustration showing structural elements of the house

Construction and Detailing

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

A tip is shaved thinly, and a piece of lumber called the Gassho-Zai is inserted in a pair of holes at both ends of the triangular base, this makes up the basic shape of the roof. It is called a “pin-structure�, it transmits the roof and the weight of thee snow to the first floor efficiently, and stabilizes the house.

To increase the strength of the house against earthquakes and strong winds, lumber is placed between the crossbeams. This lumber is called Sukijai. The wooden pillars that support the roof are called Hanegai or Kohagai.

The Gassho-style houses are flexible to cope against extreme weather conditions. The roofs of the Gassho-style houses may not be level. This is because the roof can be diverted on purpose to withstand the weight of the snow.

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Section 1 | 2 | 3

Roof Plan | Construction technique Gassho-Zukuri Styled Minka Village

Re-thatching of the Gassho-Style Roof The most distinctive part of the Gassho-style house is the thatched roof.

Construction of the thatched roof requires many personnel, this was typically done with the help of Yui; volunteer neighbours.

Straw is acquired from crops that has been harvested during the autumn, it is then dried and used as a snow fence around the house, Re-thatching was typically done either during spring or autumn.

Before the roof is ready to be re-thatched, a scaffolding is constructed to help remove the old roof, and the old straw is separated into piles of good and bad straw. Good straw is reused, it is mixed with the new straw and placed at the ridge of the roof.

Figure. Image showing a roof being rethatched. About 100 people are on the roof of the house, with 300-400 more working inside or on the ground.

Each side of the roof is divided into three, as re-thatching is done in three stages, and constructed from bottom to top. Bundles of straw are joined at the end beside the roof, this process is called Hafu-Jiri, and the angle of thatching is linked to the eaves by Hafu-Jiri. Only skilled craftsmen can make Hafu-Jiri, If the borderline between the old and new straw isn’t covered the Hafu-Jiri could leak if it rained or snowed.

The eaves of the roof made along the Hafu-Jiri is called the Ojiri, the roof’s thickness is indicated by the Ojiri and standardised according to it, it is then covered by a layer of Thatching. Finally short thatching is used to cover the ridge and long thatching is bent over the ridge.

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Figure. Typical materials used to construct thatched roof

Figure. Typical structural layout of a pitched roof

Structure - Materials used

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Construction of the Minka House A unique construction feature of the Gassho-Zukuri style houses was the disregard for usage in nails or metal materials to create the house and instead, heavy focus on naturally-sourced straw and wood materials from the surrounding forests. During winter season, the thatch roof provides excellent insulation from the thick and dense straw exterior.

Thick snow that piles onto the house easily sheds off as both sides of the roof are steeply-sloped, mimicking the shape when a person's hands are put together with the palms facing inward.

The structure of the roof was designed to support the remaining piled snow and prevent the house from being crushed. This created a spacious upper area which was often utilized for raising silkworms and making washi paper.

Figure. Miscanthus grass, a type of pampas, is stored under the eaves of a shed to keep it dry in readiness for thatching. The roof thatch can be up to 1 meter (3 feet) thick.

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Figure. Structure of a Gassho-style house

Construction sequence

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Typical Sequence of Construction of Roof 1.

Large rafters are attached to the ridgepole.

2.

Horizontal beams are placed across the rafters at right angles.

3.

Small rafters are used to create a grid between the large rafters.

4.

The exterior surface is covered with reed mats.

5.

Thatch bundles are placed over the reed mats and tied to the roof frame with vines inserted through the mats.

6.

Large beams, to which the floor is attached, are tied to the large rafters at each floor level.

7.

Diagonal poles are attached to the large rafters on the inside of each roof slope.

8.

Large cross beams, parallel to the floor, connect the two roof slopes on

Figure. Materials and structural elements in a minka house

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Weathering straw coat Ridge securing spars Wooden poles bound together by straw ropes Dense straw foundation

Figure. Section of thatched roof

Figure. Exploded View of Thatched Roof

Reed mat Vertical batten

Blocking pinned to rafter feet Oak facing fillet

Existing wall

Figure. Thatched roof detail

Detailing and joints

Section 1 | 2 | 3

Gassho-Zukuri Styled Minka Village

Wooden poles follow a grid layout with occasional diagonal supports. They are bound together with thick straw ropes.

An improved version of the Traditional Square Lash technique which provides a quicker and more efficient process while retaining the strength of the lash.

The Mortised rabbeted oblique scarf splice is often used for joining groundsills, girders or beams. Its shape allows for easy assembly which makes it a popular option for primary beams.

This simple splice, Stepped dovetail splice, is commonly used to join the grounsills.. The snug fit prevents axial shifting making it useful as a foundation for the house.

This decorative splice, Halved rabbeted oblique scarf splice, is often used for finishing, particularly on exposed ceiling members. The length of the inclined plane is made equal to the size of the cross section when needed for stronger structural use.

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3 (hot season) 1

3 (cold season)

2

Figure. Section showing different passive strategies

Section 1 | 2 | 3

Passive Strategies - Thatched Roof Gassho-Zukuri Styled Minka Village

The Kiritsuma Style Thatched Roof 1. PROTECTION AGAINST STRONG WIND AND SNOW Shaped like a triangle, they are stable and far more effective when dealing with excessive weather, especially during a snowstorm. As it snows heavily in winter in this region, this steeply-sloped roof helps the snow to slip off and prevents the house from being crushed.

2. THERMAL EFFICIENCY The natural ventilation underneath the top roof layer significantly improves the thermal efficiency of a building.

This ensures optimal indoor comfort both in winter and summer.

3. MAXIMUM SUN LIGHTING AND INSULATION Compare to a flat roof, the pitched roof has higher total surface area to receive sunlight. This feature allows better thermal comfort during the winter season as it reduce the use of mechanical heating and also keeps the heat seal in.

During summer times, the thatched roof act as an insulator against the heat.

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