LOW-COST HOUSES FROM
'SMALL-DIAMETER TREES,
PLANTATION THINNINGS, AND
TREE TOPS AND BRANCHES
Published by tIN
FOIEST PRODUCTS IESEAl.CH AND DEVELOPMENT INS1'ITU1E
DEPARTMENT OF SCIENCE AND TECHNOLOGY
~ft
nmaNAn01lAL TltOPlCAL TIMIU OItGAIIIZA-':::
LOW-COST HOUSES FROM
SMALL-DIAMETER TREES,
PLANTATION THINNINGS, AND
TREE TOPS AND BRANCHES
l'uhUshed hy the
FOREST PRODUCTS RESEARCH AND DEVELOPMENT INSTITUTE
DEPARTMENT OF SCIENCE AND TECHN OLOGY
College, Laglma 4031
Philippines
alld the
INTERNATIONAL TROPICAL TIMBER ORGANIZATION
International Organizations Center
5th Floor Pacifico-Yokohama, I-I,
Minato-Mirai, Nishi-Ku
Yokohama 220, Japan
THE FOREST PRODUCTS RESEARCH
AND DEVELOPMENT INSTITUTE
The Forest Products Research and Development
Institute (FPRDI) is the research and development arm
on forest products utilization of the Department of
Science and Technologv (DOST), the body that
coordinates and manages the Philippines' national
science and technologv system.
Its functions include: 1. the conduct of basic and
applied research and development on forest products
based on the needs of the wood-using arid related
industries and the general public; 2. the transfer of
completed Rand D results to end-users via linkages,
and 3. the provision of technical services and trainings
to various clientele.
THE INTERNATIONAL TROPICAL
TIMBER ORGANIZATION
The International Tropical Timber Organization (ITTO) is
a consortium of timber-producing and timber-using
countries worldwide. It encourages and supports the
efficient and improved management of tropical forests
and wood utilization including the utilization of lesserknown and plantation-grown timber species; sustainable
utilization and conservation of tropical forests and their
genetic resources, and maintenance of an ecological
balance in the areas concerned.
CONTENTS
Introduction
1
Technology Generation
3
I. Lumber Processing Technologies
5
• Sawmilling Systems for SDLs
(Saw-Dry-Rip Process)
• Lumber Dryer Heated by NonConventional Sources
• Treatability of Lumber from SDLs
• Stress-Grading Machine for Structural Lumber
• Housing Components from SDLs, Plantation
Thinnings and Tree Tops and Branches
5
S
10
12
14
11. Veneer and Plywood from SDLs, Thinnings
and Tree Tops and Branches
17
Ill. Woodwool Cement Boards from SDLs,
Thinnings and Tree Tops and Branches
19
IV. Design and Construction of Low-cost Houses
from SDLs, Thinnings and Tree Tops and Branches
21
INTRODUCTION
Providing adequate shelter to are rapidly vanishing. Most of
which ·, once
the millions of underprivileged these forests
and homeless continues to be a catered to foreign needs are
major goal of the Philippine now exploited for domestic
national
government today. consumption.
The
country's
burgeoning
population estimated to reach Cognizant of this scenario's
70 million by the year 2000 repercussion on the wood and
industries
puts pressure on this task. "' wood-based
Add
to
that the natural especially the housing and
industry,
the
calamities that cause untold construction
damage to lives and property, . Forest Products Research and
Institute
and the escalating prices of Development
non-wood
construction Department of Science and
materials like cement, hollow Technology (FPRDI-DOST) in
blocks,
steel
and
related College, Laguna, Philippines
products. Over the next five and the International Tropical
Organization
(lTTO)
years, at least 1.2 million Timber
housing
units
are
being based in Yokohama, Japan
targetted to be built as partial collaborated in the search for
alternative yet cheaper woodanswer to this need.
based · sources of building
Because of its properties, materials.
wood remains the most popular
material in the construction The
FPRDI
proposed
business.
It is suitable for project on "Low-cost Houses
structures like walls, external from Small Diameter Trees,
claddings, floors, joinery and Plantation Thinnings, Tree Tops
interior furnishings. Wood also and Branches", which
lends itself to modular and subsequently
approved
for
prefabrication systems, thus implementation
with
funds
hastening construction time. from the ITTO.
Traditional sources of wood for
construction are the premium Among
the
non-traditional
wood species or those with wood-based materials identified
diameters of
above 60 cm. as substitutes for conventional
But the country's forests, once wood
and
wood-based
a treasure trove of resources,
construction
materials
logging wastes, milling wastes
and plantation thinnings.
All
these
materials
can
be
converted
into
building
components
provided
appropriate technologies are
developed to process these
resources into cheap but of
acceptable quality products.
Despite the impending log ban
in the country, some forms of
logging still continue.
The
operations generate wastes and
residues in the form of tops and
branches,
culled
and
abandoned ~ogs, stumps and
damaged res.iduals. The FPRDI
found that for every ' cubic
meter of log extracted from the
forest, about 0.8 cubic meter
of logging
wastes is left
behind.
other
hand;
the
the
processing efficiency of local
sawmill
and
veneer
and
plywood plants is estimated to
be 50%. This means that for
every cubic meter of log
into
lumber
or
processed
veneer and plywood, one half
becomes mill waste in the form
of slabs, sawdust, trimmings,
edgings, rounding-up waste and
As of 1992, the country's
residual or sec'ondary forests
stand at about 3.13 million
hectares. An ongoing program
on Timber Stand Improvement
(TSI) by the Department of
Environment and
Natural
Resources
(DENR)
involves
thinning of second growth
forests to remove defective
trees, reduce the number of
secondary species and free the
primary
species
from
competition to ensure better
growth
conditions
for
the
selected trees that will form
the final crop. This operation
can yield at least 300,000 to
400,000 m 3 of raw materials
per year with diameters ranging
from 10 to 40 cm.
The DENR is actively pursuing
the development of plantations
both thru the private sector in
terms
of
industrial
tree
plantation (ITP) scheme and its
own reforestation program. As
of 1992, the Philippines has
about 0.48 million hectares of
ITPs.
A number of these
plantations are more than 30
years old and promising as
potential
sources
of
raw
materials
for
the
housing .
industry.
Plantations are subjected to
thinning operations similar to
the thinning of residual stands.
Thinning is a periodic activity
during the rotation of the
plantation.
The
materials
removed during the thinning
oper"ation yield raw materials.
Plantation-grown timbers and
thinnings
share
the same
characteristics of being small in
diameter, of lower specific
gravity, younger and therefore
a higher proportion of juvenile
wood.
TECHNOLOGIES GENERATED
The 12 studies comprising the
FPRDI-ITTO project on cheap
housing from non-traditional
wood materials were grouped
into four categories: 1. raw
material
preparation;
2.
of
housing
development
components, house designs
and construction; 3. socioeconomics of producing raw
materials from non-traditional
sources including construction,
and
4.
promotion
and
dissemination of the developed
technologies.
The project
generated
a
package
of
environment
friendly
technologies to extract the
potential of the small-diameter
logs, plantation thinnings and
tree tops and branches (see
schematic diagram).
Logs from small-diameter trees
and thinnings are processed
into lumber which are dried and
treated with preservatives to
prolong service life.
Lumber
intended as structural members
for trusses, columns and beams
are subjected to stress grading.
Low-stress grade non-structural
members
include
panelling
materials, doors, jalousies, door
and
window
jambs
and
battens.
Veneer and
plywood
wood wool cement boards can
also be harnessed from SOLs,
thinnings
and
tops
and
branches.
These
panel
products are ideal as partition;
ceiling and kitchen cabinet
materials.
The collaboration between the
FPRDI and the ITTO resulted in
the design and development of
a low-cost house which even
an ordinary wage earner can
afford.
It is hoped that the
majority of the Filipinos will
benefit from this undertaking.
~
SCHEMATIC DIAGRAM OF THE PROJECT
'LOV-COST HOUSES FROM SMALL DIAMETER TREE~ PLANTATION
THINNING~ TREE TOPS & BRANCHES'
I
VD£ER PRDllUCTlIl'l
--_._,
I
GUJING &.
CtlNSTRUCTIDN Of"
RA.. MAT£RIA!..CSIV
LD'w'-COST HIlDEL
HOLIS£S
1. ITPS
2. PlNITATlIIN
TH!h!rum
3. l1JPS AND
BRANCI£S
CHIP PRODUCTlIIN
BOI\RD PRIlDUCTIDN
- ~ StftJlllING
-MIXINti.IIAT F1lRKING.
CILlJ PRESSING
AND F1.AIC!NG
- SrwaHG. DRYING
RA 'vi
MATERIAL
AND CUWING
-ct.R!Ni AND CONDITIONING
- TJUIIoIINGS
PROCESSES
NOTE, ECIlNCKlC CDHPIlNENTS CUTS ACROSS THE. VHCL£ PROJECT.
- EXTERIllR \{AU.
PART~
I
I
PRODUCTS
LO'vl-COST HOUSES
5
I. Lumber Processing Technologies
Sawmilling Systems for SOLs (Saw-Ory-Rip Process)
Technology Description
The technology provides an economical and efficient method in
converting small-diameter logs into lumber.
This involves
appropriate machinery and log breakdown pattern to optimize
lumber recovery and at the same time minimize or prevent a major
problem associated with the conversion of small hardwood logs
into lumber - the tendency to warp excessively during the drying
process.
Technical and Economic Advantages
. Lumber yield. The average lumber recovery in big band mills is
about 60% for large-diameter logs. Lumber recovery for the small
band mills used in the st.udy for milling logs as small as 1 2 cm in
diameter averaged 57%, 60%, 64% and 56% for the table-type
bandmill, wood mizer (horizontal mobile bandmill), ARAKAWA and
PTPI band mill, respectively.
Efficiency. The adaptability of small band mills for milling small
logs leads to a more efficient and economical processing operation
compared with bandmills designed for large-diameter logs. This
may '· be attributed to less problems in handling the logs, lesser
power requirements and smaller saw k~re (blade is thinner, i.e.,
gauge 19 or 20). Depending on the species and size.s of logs,
small band mills can process up to 3 m 3 of logs per hour. ·
Labor and Materials.
Small bandmills require less steps in
operations than big band mills. Small band mills particularly the
wood mizer (mobile horizontal band mill) can be operated by at
least three persons.
6
Logs smaller than 30 cm in diameter are difficult to handle in big
band mills. In small bandmills, specifically the wood mizer, logs at
least 1 m long and 20 cm in diameter can be efficiently processed
into lumber.
Lumber Quality. With the application of the SDR process, warp
The
development in lumber may be minimized or prevented.
traditional practice of sawing the lumber to required dimensions
prior to the drying operation results in excessive warping
particularly in speci~s with high growth stresses (e.g., fastgrowing trees).
Based on the study on bagras (Eucalyptus
deglupta) , warped lumber was reduced to nil in the SDR versus
28% in the traditional sawing system.
Sawmilling System. -Any of the four types of mills studied offers
an efficient and profitable method of processing small logs into
lumber in the countryside. Depending on the log supply, these are
suitable for small to medium-scale saw milling operations.
However, in terms of processing cost per board foot, the wood
mizer (mobile horizontal band mill) is the most economical system.
It is also adaptable to a wide range of conditions. Sawmilling is
possible in any accessible site near or within the forest.
Processing cost per board foot may be as low as P 0.42
depending on the lumber production per hour.
Financial Feasibilities
[For mobile horizontal sawmill operation (wood-mizer)]
Initial Investment Cost
I.
Fixed Investment
• Land
• Buildings
• Auxilliary and service
facilities
• Plant machinery and
equipment
Total Fixed Investment
Amount (P)
180,000
750,000
1,035,000
2,200,000
P 4.165.000
7
11.
Pre-operating Capital
Ill.
Working Capital Requirement
44,000
TOTAL INITIAL INVESTMENT
1,281,185
P 5.490,185
Financial Indicators
Net Present Value
Internal Rate of Return
Return on Investment
Payback Period
=
=
=
=
P 889,184
22.84%
25.96%
4 years
8
.Lumber Dryer Heated by Non-conventional Sources
Technology Description
This is a 2.35-m 3 (1,000 bd ft)-capacity solar lumber dryer with a
back-up heater. It can accomm,odate a load m~asuring 10 x 4 x 5
ft on 3/4~inch stickers. The roof, two sides and the rear end are
covered with plastic sheets (double-wall mylar) for trapping the
UV rays of the sun. Two propeller-type fans (61 cm diameter),
run by 1 hp electric motor, provide air circulation. The back-up
heater, made of empty drums welded "end to end and attached to
a wood waste-fired furnace, provides energy at nighttime. To
increase humidification, a spray line is installed above the empty
drums to produce mist. A butterfly damper attached to the base
of the chimney controls the combustion rate. The dry bulb and
the wet bulb thermometers control the drying conditions based on
a predetermined drying schedule. The kiln operator controls the
feed rate of fuel and the drying condition based on the set point of
the drying condition.
The south side is made of marine plywood (double-walled) where
the main door and the four vents are installed. The vents likewise
control the drying condition inside the kiln.
Technical and Economic Advantages
Heat source. Source of heat during daytime is the sun. This
saves at least 30 to 35 % of the cost for generating heat energy.
In kiln drying, 60% of the total production cost goes to energy
generation.
Additional heat source.
A back-up heater can be used at
nighttime. The back-up heater is a furnace fueled by biomass or
agricultural wastes. The design is simplified and the materials
used for construction are locally available.
The quantity of
materials that can be dried in the solar dryer is comparable with
that in the conventional type lumber dryer although drying time
takes 2 to 3 days longer.
9
Availa bility of Materi als. The kiln design is suited to rural
areas,
and the kiln compo nents are locally available excep t
for the
glazing mater ials which are of plastic film.
Drying condit ions. The required workin g tempe rature of 150°F
is
attaina ble in the system . Based on the workin g tempe rature
, an 8
to 1.0% MC is attaina ble in a period of 10 - 14 days for
25-mm thick lumbe r mater ials which are accep table in the expor t marke
t.
Note: Althou gh the results of initial .tests are promis
ing, the
lumbe r dryer needs furthe r testing for verific ation purposes.
10
Treatability of Lumber from SDLs
Technology Description
By following established preservative treatment schedules, wood
considered to be inferior, perishable or of low durability can be
protected against attacks of wood-destroying organisms. Building
components like trusses, outer walls, framings and other portions
of the house must be properly treated to prolong their service life.
Preservative treatment of wood is done by applying either
pressure or non-pressure methods.
Pressure-treated wood,
however, is not easily available. Moreover, pressure treatment is
not always economical, desirable or feasible.
Thus, non-pressure treatment becomes an alternative. Two of the
commonly used non-pressure treatments are soaking for air-dried
In
and kiln-dried lumber and dip-diffusion for green wood.
soaking, wood is submerged in a tank of water-borne or oil-borne
preservative and allowed to soak for several days or even weeks.
Dip-diffusion, on the other hand, is done by momentarily dipping
the green wood in highly concentrated solution, and allowing the
preservatives to diffuse for several days or weeks in tightly sealed
polyethylene bags.
Technical and Economic Advantages
Soaking Method. The optimum treatment schedule established for
small-diameter logs is 5-day soaking in 6% or 8% concentration of
borax-boric acid or chromated-copper-arsenate (CCA).
This
schedule yields retention and penetration values required in wood
for indoor use and for exposure to weather.
Preservative absorption is most rapid in the first 2 or 3 days but
continues indefinitely at a decreasing rate.
This method does not require preDip-diffusion Method.
conditioning of sawn timber. It can be applied to every timber
11
considered difficult to treat can be penetrated by preservative.
The best treatment combination for this method is 30%
concentration of borax-boric acid and 1 5-day diffusion period.
Other Advantages. Non-pressure preservative treatment, either
the soaking or dip-diffusion method, can be done even outside
the wood treatment plant. It is also more practical in rural areas
and in housing construction where it is applied on some housing
components and mill work, in the control of sapstain in freshly cut
lumber and remedial treatment of partially decayed utility poles.
Although the degree of protection using non-pressure method is
less compqred with pressure treatment, it can be improved by
observing proper treating schedules .
..
12
Stress-grading Machine for Structural Lumber
Technology Description
Stress-grading of lumber is the sorting of sawn lumber into
specified stress grades to ensure quality control and confident use
of graded timber for structural purposes.
The FPRDI-developed stress grading machine employs a timber
frame to which are attached a cable, pulleys and a lever for easy
loading and unloading of a specified weight for flexing the timber
to be graded. A dial gauge with a sensitivity of 1/10 mm (1/1000
inch). placed underneath the center span of the timber measures
deflection upon loading.
The stress grading machine is so simple that it can be fabricated
locally. It can predict the basic stresses of wood with acceptable
precision by using the deflection criteria established for each
grade (Tables 1 and 2).
Technical and Economic Advantages
Accuracy. It can stress-grade lumber with reasonable degree of
accuracy regardless of specific gravity, moisture content and
presence of defects which can affect strength.
Lumber Quality. The lumber quality is assured because the design
stresses can be predicted through stress grading ~
Marketing. Newly discovered lumber is easier to sell since stress
grading is done in terms of strength instead of specifying the
species, thus simplifying the design and specification procedures.
Cost of Stress Grading Machine
P 10,000
Table 1. Maximu m deflecti on limits (mm) for gra~ing timber
.at EMC or 16.±. 2% MC
SECTION
TxW
(mm)
45
45
45
45
45
x 45
X. 70
x 95
x 120
x 145
SPAN
m
APPLIED
WEIGHT
(kg)
1-F36
2-F29
3-F23
4-F18
5-F15
6-F12
F9
F7
1.354
1.569
1.737
1.878
2
96.3
96.3
96.3
96.3
96.3
7.4
7.4
7.4
7.4
7.4
8.9
8.9
B.9
8.9
8.9
10.7
10.7
10.7
10.7
10.7
13
13
13
13
13
15.6
15.6
15.6
15.6
15.6
18.9
18.9
18.9
18.9
18.9
22.8
22.8
22.8
22.8
22.8
27 .4
27.4
27.4
27.4
27.4
STRENGTH GROUP OR STRESS GRADE DESIGNATION
Table 2. Basic stress for the differen t properties at EMC or 1 6 .±. 2
% MC
STRENGTH GROUP OR STRESS GRADE DESIGNATION
PROPERTY
1-F36
2-F29
3-F23
4-F18
5-F15
6-F12
MOR (MPa) ·
36.50
14.40
26.00
10.50
4.'00
695
0.484
· 29 .40
. 12.10
20.40
7.25
3.15 .
525
0.355
23.40
10.20
15.50
5.04
2.55
395
0 .269
18.80
8.50
12.40
3.50
2 .05
300
0.188
15.00
7.20
9.60
2.42
1.65
. 225
o 155
12.00
6. 10
7.50
1.'56
1.30
170
0.096
MO~(GPa)
MCS (MPa)
GP (MPa)
SH (MPa)
JS (NI
S slip ,(mm)
F9
9.60
5.10
5.80
1.17
1.05
170
0.096
F7
7.70
4.30
5.80
1..17
1.05
170
0.096
14
Housing Components from SDLs, Thinnings,
and Tree Tops and Branches
Technology Description
This technology involves the utilization of small-diameter trees,
plantation thinnings and tree tops and branches to augment the
supply of commercial timber for housing components such as
trusses, columns, beams, doors, windows, door and window
jambs. A set of working stresses for each strength group was
established and related to this, a systematic way of sorting the
timber was developed through the use of a simple stress grading
machine.
The use of stress-graded timber is very effective when designing
structural members like trussed rafters, columns and beams. The
FPRDI-developed truss system, for instance, shows a balanced
design of the structural members aimed at efficient timber
utilization. The trusses are engineered to use minimum section of
timber, just sufficient to withstand imposed dead load, live load
and wind forces prevailing in the three typhoon zones of the
Philippines.
Technical and Economic Advantages
Strength Grouping. Classifying a timber species to a particular
strength group based on its specific gravity is convenient for
design information purposes.
This facilitates marketing of
especially the non-commercial 1umber products since grouping is
done in terms of strength rather than specifying the species. Each
member species within a group can substitute for another so that
newly discovered timber, when grouped with the more common
species, can easily enter the market.
Grading System. This employs a simple stress grading machine
that is easily constructed yet can predict with acceptable
15
precIsion . the wood's basic design stresses using the deflection
criteria derived for each grade.
Investment. Minimal investment is needed since the processing of
raw materials into housing components requires no sophisticated
processes, rollers and other expensive equipment for assembly.
An ordinary hammer, hand or table saw and flat surface or
flatform jig will suffice. Greater return of investment can be
expected with the use of alternative materials from SDLs,
plantation thinnings, tops and branches.
Fabrication. The components can be fabricated either in the
construction site or in the factory for mass production. It is
economical when undertaking construction in remote areas or
where factory-made commponents using imported technoJogy are
either not available or the transport cost is prohibitive.
Installation. Since the components are prefabricated, construction
time is faster.
Financial Feasibility
(Based on 14 trusses, 1 set door/jamb, 2 sets window/jamb,15
beams and 1 5 columns fabricated)
Initial Investment Cost
I.
Fixed Investment
o Land
o Buildings
o Auxilliary and service
facilities
o Plant machinery and
equipment
Total Fixed Investment
11.
Pre-operating Capital
Ill.
Working Capital Requirement
TOTAL INITIAL INVESTMENT
Amount (Pl
240,000
750,000
1,020,000
1,492,550
P 3.502.550
29,851
1,652,253
-P 5,184,654
16
Financial Indicators
Net Present Value
Internal .Rate of Return
Return on Investment
Payback Period
=
=
=
=
P 1,261,134
25.51 %
18.41 %
3 years and
6 months
Finger-jointed and Nail Laminated
Columns and Beams from Plantation
Thinnings, Tree Tops and Branches
Technology Description
Wooden structures like columns and beams from small-diameter
trees, plantation thinnings and branches do. not meet the length
and cross-section r-equirements, hence they are finger-jointed and
glue-nail laminated 'respectively. The low-grade spedes is used in
portions not subjected to high stress, while the high strength
species is put in portions of greater stress.
In beams, for
instance, the low-grade species is placed at the center,
sandwiched by the higher-grade species. This eliminates strengthreducing defects such as knots, checks/splits and wane, thereby
upgrading otherwise poor quality materials.
.
Finger-jointed and glue-nail laminated structural members and solid
wood possess comparable strength.
17
11. VENEER AND PLYWOOD FROM
SDLs, THINNINGS AND TREE
TOPS AND BRANCHES
Technology Description
The technology is a very low-investment business addressed to
community forest-based enterprise. It involves the I use of nonconventional 60 cm rotary veneer lathe, a furnace-type veneer
dryer and a cold press system in the production of small-size
plywood from small-diameter logs. It further applies glue/glue mix
suitable for veneers with 1 8 % moisture content.
Economic and Technical Advantages
Veneer Yield. Green veneer recovery is found to be high (48% to
73%) compared with that of the traditional system of cutting
veneer (55 %). A 60-cm rotary veneer lathe is used to process the
SDLs into veneers.
Drvino. Energy consumption is reduced since the furnace-type
veneer dryer uses very low temperatures of 60 - 70°C versus the
more than 100°C temperature required in conventional dryer.
Moreover, the dryer is fueled by woodwastes. The system of
gluing accepts veneers with 1 8 % moisture content in contrast to
the 8 - 12% MC in conventional gluing, thus making for savings in
drying of veneers.
Of the various glue mixes
Gluing and Pressing System.
formulated for veneers, the one with 100 pbw urea-formaldehyde
powder, 75 pbw water, 20 pbw filler and 3.25 pbw catalyst is the
best for indoor plywood. It is applied using the cold press system
which, unlike the hot press system, does not need a boiler for
steam generation. Only 4 hours is needed for the glue mix to set
compared with the 8 hours for commercial glue.
The bond
18
strength passed the requirement in accordance with the PNS
standard.
Plywood Size. Smaller-sized plywood (2 ft x 2 ft, 2 ft x 4 ft) can
be produced which are deemed more versatile than commercial
plywood (4 ft x 8 ft) as partition, ceiling and kitchen cabinet
materials.
Financial Feasibilities
(Based on 396 and 198 pieces of 2 ft x 2 ft and 2 ft x 4 ft
plywood, respectively, per 8-hour operation)
Initial Investment Cost
I.
Amount (P)
Fixed Investment
o Land
o Buildings
o Auxilliary and service
facilities
o Plant machinery and
equipment
240,000
750,000
1,035,000
1,317,019
Total Fixed Investment
P 3,342,019
11.
Pre-operating Capital
Ill.
Working Capital Requirement
26,340
TOTAL INITIAL INVESTMENT
524,590
-P 3,892,949
Financial Indicators
Net Present Value
Internal Rate of Return
Return on Investment
Payback Period
=
=
=
=
P 955,582
24.77%
16.17%
3 years and 1 0 months
19
Ill. WOO DWO OL CEMENT BOARDS
FROM SDLs, THIN NING S AND
TREE TOPS AND BRANCHES
Technology Description
Wood wool cemen t board (WWCB) is a panel produ ct
made of
shredd ed wood, bonded with ordina ry portlan d cemen t, with
some
additiv es and cold-p ressed under low pressu re and
ambie nt
tempe rature . It is an energy -savin g materi al that is suitab
le for
the Philipp ines' climat e and socio- econo mic condit ions.
Like
plywo od, it finds applic ation as wall panels, kitche n cabine
ts and
ceiling s.
Model house s to demon strate the WWC B's versat ility and
variou s
applic ations were constr ucted at the Nation al Housing Autho
rity
Comp ound, the Forest Produ cts Research and Devel
opmen t
Institu te (FPRDI), the Depar tment of Scienc e and Techn
ology
(DOST) in Bicuta n, Taguig , Metro Manila and in Florida
blanca ,
Pampa nga Reset tlemen t Site for the Mt. Pinatubo
victim s.
Severa l housin g contra ctors are explor ing the possib ility of
puttin g
up big comm ercial plants to produc e this type of building
materi al.
Technical and Economic Advantages
Waste Utiliza tion. WWC B manuf acture is an enviro nment
-friend ly
proces s since agrofo rest waste s are the main ingred ients
of the
boards .
Manuf acturi ng is enhan ced by the availa bility of
indige nous raw materi als.
Worka bility. Light in weigh t by nature , WWC B is easy
to glue,
nail, paint and plaste r. Only simple equipm ent, the minim
um of
energy , and not too highly skilled manpo wer are neede
d in its
manuf acture .
20
Size. The board's dimension (2 ft x a ft x 3 /B -inch) makes it easy
to handle and transport, thus facilitating its use in modular or
prefabricated structures to hasten construction time.
Other Characteristics. WWCB can withstand the adverse effects
of earthquakes, typhoons and high humidity. It is water-, fire-,
termite-, vermin-, fungus- and rot-resistant. It also possesses
excellent insulation and acoustical properties.
Financial Feasibilities
(Based on 200 boards per a-hour operation)
Initial Investment Cost
I.
Amount (P)
Fixed Investment
o Land
o Buildings
o Auxilliary and service
facilities
o Plant machinery and
equipment
240,000
1,420,000
535,000
1,096,000
Total Fixed Investment
P 3.291.000
11.
Pre-operating Capital
Ill.
Working Capital Requirement
21,920
TOTAL INITIAL INVESTMENT
666,401
-P 3.979.321
Financial Indicators
Net Present Value
Internal Rate of Return
Return on Investment
Payback Period
=
=
=
=
P 2,842,861
34.55%
30.0%
4 years and
4 months
21
IV. DESIGN AND CON STR UCT ION OF LOW COS T HOUSES FROM SDLs, THIN NING S
AND TREE TOPS AND BRANCHES
Technology Description
The FPRDI-DOST-ITTO house is designed for and built from
nonconve ntiona l wood-based source s of building materials, i.e.,
smalldiame ter logs, planta tion thinnin gs and tree tops and branch
es.
These previo usly untapp ed materi als are processed into
sawn
timber , housing compo nents, and panel produ cts like plywo
od and
wood wool cemen t boards.
Design. It can be a one- or a two-be droom unit (see Figure
s 1 and
2). It is designed for simpli city, utility and durab ility to satisfy
the
basic requir ement s of a family of five. The open "all-in
-one"
space can be flexibl y used as a living room, dining room,
kitche n
and even as an extra bedroom. This space can also be conve
rted
into the family 's social functio n room which is not possib
le in
partiti oned quarte rs.
Install ation. Faster erectio n of the unit to save on labor
cost is
possible since some of the housing compo nents such as
doors,
windo ws, their jambs , exterio r and interio r wall framin gs
and the
truss system s are prefab ricated .
Truss Syste m. The FPRDI developed a truss system using
graded
timbe r mater ials to attain a balanced design of the struct
ure as
well as efficie nt utiliza tion of timber . The trusse s are engine
erea
to use minim um sectio n of timber just enough to withst
and the
impos ed dead load, live load and win forces prevailing
in the
install ation site. The conne ctors used for the truss joints
are
splice plates made of 13-mm thick, 5-ply pieces of plywo
od
fasten ed by flat-he ad 32 mm long nails with 3.5 mm
shank
diame ter.
/
22
A one-bedroom model house with a floor area of 26.5 m 2 was
erected within the DOST Bicutan Compound in Taguig, Metro
Manil a. The two-bedroom unit with a floor area of 32 m 2 can be
found at the Floridablanca Resettlement Site in Floridablanca,
Pampanga. A replica of the Floridablanca model house can be
seen at the University of the Philippines-College of Forestry (UPLBCF) Compound in · College, Laguna. These houses are equipped
with plumbing and electrical fixtures and a septic vault.
Construction Cost
{For a 2-bedroom house as of Sept. r993f
•
•
•
•
•
•
Concreting work
Masonry
Carpentry
Tinsmithry
Plumbing
Electrical
TOTAL DIRECT COST
(excluding labor)
P 4,080
5,708
49,723
7,700
2,345
2,149
P71,705
23
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24
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Fig. 2.
ALE =
I : 50 M
Two-bedroom house
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I