Bamboo Construction
Bamboo is one of the oldest materials people have used to
increase their comfort
and well-being. In today's world of plastics and steel,
besides continuing to make
its traditional contributions, bamboo is growing in
importance. Outstanding
varieties of bamboo from throughout
the world are being tested to
find out how they can contribute
to local economies.
As the best species are identified
and disseminated, their use will
help to improve the lives of many.
With a few plants of superior
bamboos in the backyard, a family
will have at hand the wherewithal
to fence the garden, build a pigpen
or chicken coop, or add a room to
the house. The family will also be
able to increase its daily income by
making baskets or other specialties
for sale or exchange.
Bamboos are prominent elements in
the natural vegetation of many
parts of the tropical, subtropical
and mild temperate regions of the
world, from sea level to altitudes
or more than 13,000 feet (4000m).
People have widened the distribution
of many species of bamboo,
but some of the more valuable
species have not been distributed
as much as they could be.
Bamboo can be prepared for use in construction with simple
tools. Once prepared,
bamboo can be used extensively in the construction of
houses: <see figure 1> in making foundations,
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frames, floors, walls, partitions, ceilings, doors, windows,
roofs, pipes, and
troughs. For further detail, see Bamboo as a Building
Material, by F. A. McClure.
The entries that follow explain:
o
Splitting and preserving bamboo
o
Bamboo joints
o
Making bamboo board
o
Bamboo walls, partitions, and ceilings
PREPARING BAMBOO
Splitting Bamboo
To prepare bamboo for use in construction, the culms (stems)
must be carefully
split.
Tools and Materials
Iron or hardwood bars, 2.5cm (1") thick
Ax
Steel wedges
Wooden posts
Splitting knives (Figure 4)
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Several devices can be used for splitting culms. When bamboo
is split the edges of
the bamboo strips can be razor-sharp; they should be handled
carefully.
Splitting Small Culms
Small culms can be split to make withes (strips) for weaving
and lashing:
o Use a splitting
knife with a short handle and broad blade to make four cuts,
at equal
distances from each other, in the upper end of the culm (Figure 2).
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o Split the culm
the rest of the way by driving a hardwood cross along the
cuts (Figure 3).
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o Using a
long-handled knife (see Figure 4), cut each strip in half (see Figure 5).
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A strip of
bamboo can be held on the blade to make it thicker and speed
up the work.
o Use the same
knife to split the soft, pithy inner strip from the hard outer
strip (see
Figure 6). The inner strip is usually discarded.
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Splitting Heavy Culms
o Build a cross of
iron or
hardwood bars
about 2.5cm
(1") thick,
and place it on
firmly set posts
about 10cm
(4") thick
and 90cm (3") high
(see Figure 7).
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o At the top end
of the culm,
use an ax to
make two pairs
of breaches at
right angles to
each other (see
Figure 7).
o Hold the
breaches open with
steel wedges
placed a short
distance from
the end of the
culm, until the
culm is on the
cross as shown
in Figure 7.
o Push and pull
the culm until
the cross splits
the whole
culm.
o To split the
culms again after they are split into four strips, use a simple
steel wedge
mounted on a post or block of wood (see Figure 8).
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o Paired wedges
solidly mounted on a block or heavy bench can be used to
split strips
into three narrower strips (see Figure 9).
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Bamboo Preservation
Most bamboos are subject to attack by rot fungi and
wood-eating insects.
Bamboos with higher moisture and starch content seem to be
more prone to
attack, and insect pests may be more of a problem in some
seasons than others.
So bamboo should be cut if possible in the bugs'
"off-season." There are many
methods for making bamboo more resistant to attack. A simple
method that
combines proper curing and the use of a pesticide
(insecticide and/or fungicide) is
described here.
If bamboo is to be used to hold food or water, the only
treatment recommended
is immersion of green bamboo in a borax-boric acid solution
(see Bamboo Piping).
Tools and Materials
Machete and hacksaw for felling and trimming bamboo culms
Pesticide-choice depends on the insect or fungus pests that
are prevalent in your
area. Consult your local extension agent or farmers in the
neighborhood about the
type and its use. Follow directions carefully.
Talc-to mix with dry pesticide according to package
instructions. If talc is not
available, other dry dusty materials such as finely powdered
dried clay is used.
Dusting bag (made from cloth with an open weave)
Bamboo should not be cut before it is mature. This is
usually the end of the third
season. Freshly-cut bamboo culms should be dried for 4 to 8
weeks before being
used in building.
A clump-curing process tested by the U.S. Department of
Agriculture Federal
Experiment Station in Puerto Rico helps to reduce attack by
insects and rot
fungi. The steps are:
o Cut the bamboo
off at the base, but keep it upright in the clump.
o Dust the
fresh-cut lower end of the culm at once by patting it with a
dusting bag
filled with the pesticide-talc mixture. An alternative method of
dusting is to
dip the ends of the culms into a tray containing the mixture.
o To keep the
bamboo from being stained or rotted by fungi, raise each culm
off the ground
by putting a block of stone, brick, or wood under it.
o Leave the culms
in this position for 4 to 8 weeks, depending on whether the
weather is dry
or damp.
The culms should be as dry as possible before being placed
near buildings, where
wood eating insects usually are.
o When the culms
have dried as much as conditions will permit, take them
down and trim
them. Dust all cut surfaces immediately with the pesticide-talc
mixture.
o Finish the
seasoning in a well-aired shelter where the culms are not exposed
to rain and dew.
Rain will stain the culms when they become dry.
This method will
prevent damage by wood-eating insects while the culms are
drying.
If the bamboo is to be stored for a long time, stacks and
storage shelves should
be sprayed every six months with the appropriate pesticide
mixed in water or
light oil. Local conditions may shorten or lengthen the time
between sprayings.
In both storage and use, bamboo culms are best preserved
when they are protected
against rain in a well-ventilated place where they do not
touch the ground.
BAMBOO JOINTS
A number of methods of joining bamboo for making implements
or for construction
are shown in Figures 10 and 11.
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Tools and Materials
Bamboo
Lashing material: cord or wire
Machete, hacksaw, knife, drill, and other bamboo working
tools
Bamboo is useful for heavy construction because it is strong
for its weight. This
is because it is hollow with the strongest fibers on the
outside where they give
the greatest strength and produce a hard attractive surface.
Bamboo has solid
diaphragms across each joint or node, which prevent buckling
and allow the
bamboo to bend considerably before breaking.
Any cut in the bamboo, such as a notch or mortise, weakens
it; therefore, mortise
and tenon joints should not be used with bamboo. However,
notches or saddle-like
cuts can be made at the upper ends of posts which hold cross
pieces (see Figure 10, C an D).
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Bamboo parts are usually lashed together because nails will
split most culms. The
withes (strips) for lashing are often split from bamboo and
sometimes from rattan.
When all local bamboo yields brittle withes, lashing must be
done with bark, vines
or galvanized iron wire.
In bending bamboo--for example, for the "Double Butt
Bent Joint" in Figure 11-you
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can help to keep the bamboo from splitting by boiling or
steaming it and bending
it while it is hot.
Local artisans often know the best species of bamboo and
they have frequently
worked out practical methods for making joints.
BAMBOO BOARDS
Bamboo culms can be split and flattened to form boards for
use in sheathing,
walls, or floors.
Tools and Materials
Machete
Ax--lightweight, with a wedge-shaped head
Spud--a long-handled shovel-like implement with a broad
blade set at an angle to
work parallel to the surface of the board.
Large bamboo culms
Not all of the tools listed above are necessary, but they speed
up the work when
a large quantity is being produced.
o Remove the
thick-walled lower part of the culm.
o Use an ax with a
well-greased blade to split each node of the culm in
several places
(see Figure 12). This should be done carefully to avoid
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injuring one's
feet.
o Spread the culm
wide open with one long split.
o Remove the pith
at the joints with a machete, adz, or spud (see Figure 13).
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o Store the boards
as shown in Figure 14.
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BAMBOO WALLS, PARTITIONS, AND CEILINGS
Bamboo buildings can be built to meet a variety of
requirements for strength,
light, ventilation, and protection against wind and rain. A
few of the methods of
building with bamboo are described here.
The parts of a building that are not usually made from
bamboo are the foundation
and the frame.
Both split and unsplit bamboo culms are used in building.
They can be used either
horizontally or vertically. Culms exposed to the weather,
however, will last longer
if they are vertical because they will dry better after
rain.
Tools and Materials
Local bamboos
Bamboo-working tools, such as machete, hacksaw, chisel,
drill
Lashing material: wire or cord
Nails
Barbed wire
Plaster or stucco
Walls
A method commonly used in Ecuador for making walls is to
lash wide bamboo
strips or thin bamboo culms, horizontally and at close
intervals, to both sides of
hardwood or bamboo uprights. The spaces between the strips
or culms are filled
with mud alone or with mud and stones.
In Peru, flexible bamboo strips are woven together and then
plastered on one or
both sides with mud.
An attractive but weaker wall can be built by using bamboo
boards, stretched
laterally as they are attached, as a base for plaster or
stucco. Barbed wire can be
nailed to the surface to provide a better bond for the
stucco. The exterior can be
made very attractive by whitening it with lime or cement.
<see figure 15>
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Partitions
Partitions are usually much lighter and weaker than walls.
Often they are no more
than a matting woven from thin bamboo strips and held in
place by a light
framework of bamboo poles. Bamboo matting is often used to
finish ceilings and
both interior and exterior walls; bamboos with thin-walled,
tough culms are
usually used for this.
Ceilings
Ceilings can be built with small, unsplit culms placed close
together or with a
lattice of lath-like strips split from larger culms. There
should be some space to
let smoke from kitchen fires escape.
Source:
McClure, F.A. Bamboo as a Building Material. Washington,
D.C.: Foreign
Agricultural Service, U. S. Department of Agriculture, 1953;
reprinted 1963 by
Office of International Housing, Department of Housing and
Urban Development.
Sources of information of bamboo are:
Forestry Division
Joint Commission on Rural Reconstruction
37 Nan Hai Road
Taipei, Taiwan
Forest Research Institute
P.O. New Forest
Dehru Dun, India
Tropical Development & Research Institute
56-62 Grays Inn Road
London, WC 1
England
Federal Experiment Station in Puerto Rico
U.S. Department of Agriculture
Mayaguez, Puerto Rico
