Niche Markets for Economic Revitalisation of Satoyama Forest ...

1.2 Commercialisation of Wood Block
Construction in Satoyama
1.2.1 Use of Forest Thinnings for Wood Block Production
Commercial forest products from forest thinnings include
conventional pulp raw material, construction materials
for public works and building construction, and in recent
years, applications in laminated timber and plywood. As an
example, road guardrails, built with forest thinnings have
been developed in Miyazaki Prefecture and subsequently
used in nearly 900 locations throughout the country
(Forestry Agency edition, 2006a).
Another promising application of forest thinnings is the
production of wood blocks for the housing construction
industry. 21 This method produces wood blocks mainly from
naturally–dried cedar forest thinnings. A wall is formed by
sheathing the wood blocks between two pillars and fixing
them in place. According to test data from the Forest
Experiment Station of Ishikawa Prefectural Government
and the Wood Research Laboratory of Kanazawa Institute of
Technology, this construction method is considered to have
higher earthquake resistance than standard construction
wall methods. 22
Figure 4: Wood Block Method
Source: Deguchi Construction
Wood block construction of this sort is similar to construction
of log houses. Like wood block construction, log houses offer
superior earthquake resistance—utilising the four walls to
support the roof—as well as the aesthetic appeal of natural
wood interior walls. However, unlike log house construction,
wood block construction is not limited in terms of layout, size
and placement of windows, or restrictions on second story
construction.
and will not lead to sick building syndrome and the warm
look and feel and fragrant smell of the wood surface offers
aesthetic and healing properties. As a result, the wood block
construction method combines the strengths of providing a
comfortable dwelling space through the use of natural wood,
together with the freedom of layout offered by conventional
construction methods.
From the perspective of satoyama conservation, the
greatest advantage in using wood block construction is that
construction can be performed using forest thinnings. This
method uses a large quantity of tree thinnings to create
one piece of material at a standard size of 180 centimeters
in length, 10 centimeters in height, and 9 centimeters in
thickness. Also, use of such blocks would help incorporate
local materials into wood building. Notably, the long and
large diameter log materials conventionally used in log house
construction are generally imported from abroad. According
to the Japan Log House Association the proportion of log
house materials sourced domestically is a mere 14 per cent. 23
This situation makes a case for the local development of
wood blocks, which are innovative product alternatives with
a strong commercial viability potential and a sustainable,
low–cost raw material supply base.
An Example of Wood Block Constructed Home
The home in the pictures has a floor space of
approximately 120 square meters excluding the
basement garage. Except for a portion of the
construction materials and the ceiling, it is made
entirely from forest thinnings. Furthermore, except for
the floor material (Japanese cypress), Japanese cedar
from the Hakusan area has been used, amounting to
approximately 42 cubic meters. This figure, converted
into numbers of 20–30 year old trees, is equivalent
to approximately 1,800 trees. The amount of tree
thinning materials supplied to Ishikawa Prefecture
in 2005 was 22,360 cubic meters, of which, 214 cubic
meters was used for public construction projects
(Forestry Management Division, Department of
Agriculture, Forestry and Fisheries Department,
Ishikawa Prefectural Government, 2006b). Therefore,
20 per cent of the forest thinnings were used in the
building of one standard floor area home.
Also, as the wood material includes an inner air layer, it
possesses lower thermal conductivity than concrete or ceramic
tile and high insulating capacity. The wood block construction
helps regulate humidity, enhancing the possibility of creating
a comfortable dwelling even if materials such as insulation
or cloth are not used. Furthermore, wood material is natural
Figure 5: Dwelling Interior
(walls are wood block construction)
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