Timber civil engineering material - asst. proff. pramesh hada

Timber - Civil Engineering Material - for Civil Engineering Students

1. CIVILENGINEERING MATERIAL C
HAPTER
7.0 T
IMBER
(IMP FOR7 –15 MARKS)
Prepared By:
Er. Pramesh Hada
MSC in Urban Planning
B.E In Civil (Asst. Professor), 
Civil Engineering Dept.
Nepal Engineering College

2. T
IMBER
T
Timber : Sources, Types, Classification,
Characteristics,Advantages&Uses.
T
Growth&StructureofExogenousPlants
T
DefectsinTimber(pu)
T
CharacteristicsofCommonTimbertrees
T
Seasoning of Timber :Air, Water, Kiln, Chemical, Electrical
&
Boiling
(
pu
)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Electrical
&
Boiling
(
pu
)
T
PreservationofTimber
T
PropertiesandUsesofBamboo
T
Wood Based Products – Veneer, Plywood, Boards,
LaminatedBoardsetc.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

3. TIMBER
•Isoneofthe
importantconstructionmaterials
.
•Used as
structural elements in buildings, widely for
doors,windows andpartitions
and findlarge usethrough
secondary
wood products like plywood, particle boards
andlaminatedboards,etc.
•Wood Which is useful for
engineering or Other
structuralPurposeiscalled“Timber”
•
Mostly
uses
timber
–
plywood,Posts
et
.
in
Formwork
in
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
•
Mostly
uses
timber
–
plywood,Posts
et
.
in
Formwork
in
RCC,RBCetc. •Bothhardaswellassoftwoodsareinuse.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

4. •
When tree has been cut down and its stem and branches are
roughly converted
into pieces of suitable length
, then it is
known as
Rough Timber
.
•
When roughly converted timber is
further sawn and
converted into commercialized the planks,battens, posts
etc is
calledconverted Timber.
(Planks – board,plyboard,woodboards),
(battens-Partition, Roofing, something to hold)
Mostly
Timber
used
in
load
bearing
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
TIMBER
T
Mostly
Timber
used
in
load
bearing
structure iscalledstructural timber
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

5. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

6. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

7. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

8. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

9. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

10. PROPERTIES OFTIMBER/WOOD
Physical Properties : 1. 
Density
-light — very light: 
density less than 550 kg/m3
, eg. 
bamboo -moderately heavy: 
density 550 kg/m3 —750 kg/m3, eg. 
deodar 
-heavy-very heavy: 
density greater than 750 kg/m3, eg. Sal
2. 
Bulk Density 
-Defined as the mass of many particles of the material 
divided by the total
volume
they occupy.
-
Depends on air voids present in wood.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
divided by the total
volume
they occupy.
-
Depends on air voids present in wood.
3
. Moisture Movement
- Wood 
is liable to shrink or swell 
with the movement of 
moisture. (increase or decrease)
4. 
Shrinkage :
- Is a Reduction in linear and volumetric dimension due to 
drying of moisture.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

11. 5. 
Swelling (Increase in size)
-It is increase in 
linear and volumetric dimension on 
absorbing moisture
.
6. 
Sound conductivity 
-Has 
high Sound Conductivity
-Sound velocity in wood is greater than others. PROPERTIES OFTIMBER/WOOD
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
7. 
Thermal Conductivity
-Has very 
low thermal conductivity.
-so uses for maintain heat temperature in rooms.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

12. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

13. MECHANICAL AND THERMAL PROPERTIES OF TIMBER/WOOD:
T
As wood is
natural material
there is different
mechanicalpropertiesfordifferentwood
T
Mechanical properties are governed
by soil type,
climateandotherfactors.
T
Properties affected by
specific gravity, moisture
content,knotsandotherdefects.
Wood
can’t
resist
fire
and
burnt
easily
.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Wood
can’t
resist
fire
and
burnt
easily
.
T
It will be better to take
precautions to save timber
structurefromthermalaction
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

14. CHARACTERISTICS OF GOOD TIMBER(PU2010)
T
Uniform 
color, strong, durable 
and workable
T
Straight and compacted fibers
T
Fresh cut 
surface : sweet smelling
T
Struck: 
clear ringing sound
T
Relatively heavier
T
Free from all types of 
defects and disease of timber like 
knots.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
knots.
T
Planning surface: 
bright appearance with silky
.
T
Sawing: Cut with a saw -
not clogging (clogging -Become 
or cause to become obstructed) 
T
Firm adhesion of fibers and compacted  medullaryrays
T
Well seasoned
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

15. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Fibers in timber
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Defects of Timber
Sawing

16. ADVANTAGES OF TIMBER: (PU2011) T
availability: 
source and transportation
T
strength: 
light weight and higher strength
T
easy to 
handle and planed easily
T
joining: simple
T
Repair and Modification: Easy
T
superior, thermal insulation, sound and electrical  resistive
T
uses: 
furniture and decorative purpose
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
uses: 
furniture and decorative purpose
T
strong and flexible
T
corrosion resistance: excellent
T
higher shock and impact strength .
T
Quick and easy to build.
T
Cheaper than other types of building materials.
T
Easy to heat and cool depending on the weather.
T
More eco-friendly than other materials
T
Can last many years if proper maintenance is carried out.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

17. USES OF TIMBER 
It is mainly used for following categories of works 
(i) It is used for construction purposes including 
building 
construction, houseposts, beams, rafters, bridges, piles, 
poles  etc. 
(ii) It is used 
for furniture and cabinet making. 
(iii) Used for 
door and window frames
.
iv)  Uses for 
Formwork, scaffolding etc,
iv)  It is also used for heavy packing 
cases such as 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
iv)  It is also used for heavy packing 
cases such as 
machinery and similar stores. 
(v) It is used for manufacturing 
agricultural implements 
and tool handles. 
(vii) It is used for manufacturing 
veneers, plywoods, 
boards etc.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

18. HOUSEPOSTS
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
SCAFFOLDING

19. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

20. DISADVANTAGES OF TIMBER: (PU2011)
T
Defects in 
timber can reduce the life of wood
.  
T
Affected by 
relative humidity, fungi, insects.
T
Modification of general 
arrangement drawings if based 
on masonry construction 
T
Transportation and carriage access 
T
Exposure to weather before enclosed 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Exposure to weather before enclosed 
T
vulnerability to 
decay of timber when exposed to 
excessive moisture
.
T
If 
left untreated, timber become water logged and 
crack or chip.
T
Timber is more susceptible to fire than other building 
materials unless treated and maintained.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

21. T
Wood is a product obtained from the tree.
T
In simple classification of tree, it can be classified as:
1.
Standing timber 
- if a tree is 
livin
g then the timber is 
termed as Standing Timber.
2.
Rough timber 
- if a tree 
is fallen then the timber 
is 
termed as Rough timber.
3.
Converted timber 
-
If a tree is modified into 
desired 
T
YPES OF
T
IMBER
/W
OOD
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
3.
Converted timber 
-
If a tree is modified into 
desired 
size and shape then the timber 
is termed as Converted 
timber.
on the basis of mode of growth , the types of trees are : 
1. Endogenous Tree 
2. Exogenous Tree 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

22. 1. ENDOGENOUSTREE T
Trees grow in 
inward direction with the addition of fibrous (like  
of jute) layer at tip portion,
i.e the growth is longitudinal.
T
Trees are 
hollow at the core and have flexib
le stem.
e.g- Bambo, coconut, Sugarcane etc.
T
For 
construction purpose 
only bamboo can be used.
T
Are very flexible due to which they are not general ly used for 
construction material. 2. EXOGENOUSTREE T
Trees increase in bulk 
by growing outwards and distinct 
consecutive rings are formed 
in the horizontal section of such 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
consecutive rings are formed 
in the horizontal section of such 
trees.
T
These rings are called 
annual rings, 
because one such ring added 
every year, such trees grow bigger in diameter as well.
T
Life of trees can be find by counting the annual ri ngs.
e.g – Sisham, Sal, Pine etc. T
Timber  from these suitable 
for construction purpose 
These are further classified as
1. Deciduous tree    2. Coniferous tree
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

23. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

24. EXOGENOUSTREE
Deciduous tree  T
Are characterized by 
flat and broad 
lea
ves which fall in 
autumn season and 
new one appear in spring s
eason 
T
Hard wood is obtained by 
such tree 
which can be used for superior structural 
and engineering wo
rk.
e.g–Sal, Sisham, Teak etc.
Coniferous tree
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Coniferous tree T
Trees are characterized by 
needle 
shaped thin leaves which are evergreen
T
Trees bear 
conical shaped fruits and 
yield resins ( 
viscous substance )
T
Soft variety 
of woods are obtained 
T
Used is general 
constructional
purpose 
-e. g Pine, deodar  etc.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

25. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

26. DIFFERENCE BETWEEN HARD WOOD AND SOFT
WOOD(CHARACTERISTICS)
Aspects hard wood soft wood
Annual rings Indistinct Clearly distinct
Medullary rays Distinct indistinct
Color Dark Light
Strength Strong: tens, comp, shear Strong: direct pull
Weak: shear
Structure
Non
resinous
Resinous and split easily
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Structure
Non
resinous
Resinous and split easily
Weight Heavy Light
Uses Structural purpose Aesthetic and light structural
purpose
Sources Deciduous Conifers/evergreen trees
Branches Less branches More branches
Example Sal, teak, deodar, shisam Pine, chir, kail etc
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

27. SISHAM TREES
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

28. SAL TREE
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

29. TEAK WOOD
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

30. PINE TREES
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

31. DEODAR TREES
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

32. GROWTH OF A TREE 
T
Roots of the tree
suck a solution of salts from the soil
in
spring season.
T
Salts are
food for the tree and roots transmit
the same
through the trunk of tree to itsbranches and leaves.
T
Solution of
salts looses some of the moisture
because of
evaporation and absorbs carbon dioxide from the air. This
action in the
presence of sun makes the solution
a bit
viscous
.
This
transformed
viscous
solution
is
known
as
sap
.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
viscous
.
This
transformed
viscous
solution
is
known
as
sap
.
T
Viscous sap descends
below the bark and leaves a thick layer
in autumn
.
Layer of sap
left below the bark gets transformed
to wood and is known
as cambium layer
. A fresh layer is
thus added on the outside of the tree every year forming a
new annual ring
. The new ring represents a year’s growth of
tree.
T
Medullary rays carry the sap fro
m below the bark to the
interiorthereby nourishing the tree.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

33. STRUCTUREOF A EXOGENEOUS TREE(PU2009,2010)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
•Pith/Medulla/Core
•Heart wood
•Sap wood
•Cambium Layer
•Inner Bark
•Outer Bark
•Medullary rays
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

34. Pith/ medulla/core: T
It is first formed portion of trees.
T
It consist entirely cellular tissues and nourishes  the plant in young 
age. T
It is found as dead part of the trees incase of mat ured trees and 
decayed.
Annual rings:
T
Grows extra layer around the circumference of the trees per year
T
Circular concentric rings
STRUCTUREOF A EXOGENEOUS TREE
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Circular concentric rings
T
Each rings indicates the age of tree in year
Heart wood:
T
Annual rings around the pith at the innermost central portion of the 
tree section  T
Strong, durable and compact part of trees
T
Darker in color
T
Best part of trees in engineering views
T
Imparts rigidity to the trees
T
Doesn’t take active part in growth of trees 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

35. Sap wood: T
Outer annual rings between heart wood and the cambium layer 
T
Light in color and weight as well
T
Indicates recent growth and contains sap 
(Sap = A watery solution of sugars, salts, and minerals that circulates through the vascular 
system of a plant )
T
Annual rings of sap wood are less sharply defined in comparison to heart wood
T
Takes active part in growth of trees
Cambium layer: T
Thin layer of sap between sap wood and inner bark
T
It indicates sap which has yet not been converted i nto sap wood
STRUCTUREOF A EXOGENEOUS TREE
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
It indicates sap which has yet not been converted i nto sap wood
T
If barks are removed and get exposed, the cell cease and death
Inner bark: T
Inner layer covering the cambium layer
T
Protect cambium layer from any injury
Outer bark: T
A protective layer, outer skin covering the trees
T
Contains cracks and fissures sometimes
T
Consists of cells of wood fibers and is known as  cortex
Medullary rays: (Pit rays ) T
Radial fibers extending from pith to cambium layer 
T
Hold the annual rings of heart wood and sap wood together
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

36. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

37. MICROSTRUCTURE OF WOOD
T
Structure of wood apparent only at great magnifications is called 
microstructure. T
If study through microscope, it becomes evident that wood consists 
of living and dead cell of various shape and sizes T
Living cell consists
i
Membrane (consists cellular tissue and cellulose)
i
Protoplasm (granular and transparent, viscous vegetables, 
protein composed of carbon, hydrogen, oxygen, nitrogen and 
sulphur
)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
sulphur
)
i
Sap (differ from protoplasm by presence of phosphorous and 
shape is oval)
T
Types of cell on the basis of their function: i
conductive cells
i
mechanical cells
i
storage cells
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

38. T
Conductive cells
: serves to transmit nutrients from 
roots to the branches and leaves
T
Mechanical Cells: 
these cells are elongated, thick 
walled and having tightly interconnected narrow interior 
cavities
-imparts strength to the wood
Storage Cell: 
serves to store and transmit nutrients to 
MICROSTRUCTURE OF WOOD
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Storage Cell: 
serves to store and transmit nutrients to 
the living cells in horizontal direction and they are 
usually located in the medullaryrays
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

39. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Resinous wood
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

40. DEFECTS IN TIMBER (PU08,09,10,12,13)
T
Defects are either due 
to growing phases of tree 
or defect 
occurring after cutting trees 
T
Defects reduce the 
usefulness of wood as aesthetic 
appearance as well as strength 
1. Heart Shake 
-This defect usually occurs in 
over matured tree
s due to 
shrinkage of heart wood  -These cracks are mostly confined to 
heart wood portion 
and diminishing towards outward. 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
and diminishing towards outward. 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

41. 2. Star Shake 
-It is confined in the 
outward portion 
and diminishing towards center
. 
-It occurs due to 
frost action and strong 
heat of sun. 
-It is the most serious defect because it 
tends to separate single log into small 
pieces. 
DEFECTS IN TIMBER
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
3. Radial Shake 
-These are radial cracks 
extending from 
centre towards bark .
-These are similar to 
star shake but are 
irregular and numerous. 
-It occurs due to drying of sap or 
moisture .
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

42. 4. Cup or Ring Shake 
-Is the 
separation of tissue 
along annual 
rings 
-If the shake is 
whole round the annual 
ring 
then it is called ring shake and if it is 
half way round the ring then it is called cup 
shake. 
-It is due to 
unequal seasoning and change 
in humidity.
DEFECTS IN TIMBER
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
5.  Rind Gall 
-Is the 
curved irregular swelling 
on surface.
- Due to development of 
new sap layer on 
wound left 
after branches have been 
irregularly cut. 
-New layer fails to 
unite with old one and 
decay starts 
from that point 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

43. 6. Knots 
-This defect occurs due to 
formation of annual rings at right 
angles to
surface and also due to twisting of fibers.
-The roots of the 
branches yet embedded(Enclosed firmly) by the 
tissue and knots 
are formed 
- Knots reduce the 
aesthetic value and effects tensile strength 
-Knots may be round or oval shaped  DEFECTS IN TIMBER
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

44. 7. Twisted fibers 
-This defect occurs 
due to wind velocity constantly turning trees 
in 
one direction only.
DEFECTS IN TIMBER
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
8. End Splits
-Occurs 
only at the ends of log due to exposed conditions 
during 
seasoning. 
-May be prevented by 
painting the ends of log or covering with 
metallic cap. 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

45. 9. Druxinessand Foxiness 
(Druxinessis a term that is defined as a disease that is 
found in timber or wood. It is caused or brought about by 
a 
wound located in the layer known as the cambium 
which is attacked by fungus.)
(Foxiness is caused 
due to poor ventilation during storage 
or due to over maturity 
of the tree).
DEFECTS IN TIMBER
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
-These are stains or patches on the surface of timber 
which destroy the appearance and may cause decay of 
timber 
-Stain may be in form of white patches or mottled 
reddish colour.
(stains -A soiled or discolored appearance
)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

46. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

47. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

48. SEASONING OF TIMBER
: (PU09,10,11)
T
Wood is
hygroscopic material, dry wood absorbs moisture
from
surroundings
T
Freshly cut wood may contains more than
50% water
in the
form of sap and moisture
T
After
removal of such water
from wood then it can be used in
diff.engineering works
T
Thus
drying processof timber
is known as seasoning of timber
T
Moisture must be
extracted during seasoning under controlled
conditions
as
nearly
as
possible
at
a
uniform
rate
from
all
parts
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
conditions
as
nearly
as
possible
at
a
uniform
rate
from
all
parts
ofthe timber
T
If the
drying is irregular, the shrinkage of timber
will also be
irregular and it willsetup internal stressesbetween the fibers
T
Moisturecontent in wood may be:
T
Free moisture: present in cell cavities (major part)
T
Bound moisture: present in cell wall ( associated with the body of
timber)
o
Free moisture/ water evaporated first and the point at whichcell
cavitiesno longer contain free water is known as fiber satur ation point
.Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

49. FOLLOWING ARE THE DIFFERENT OBJECTIVES OF
SEASONING:
T
Timber 
to burn readily, if used as fuel
T
Decreased the weight 
of timber: easy handling and 
low cost
T
Impart 
hardness, stiffness, strength, better electrical 
resistance. 
(stiffness - hard to bend)
T
To increase 
resisting power of timber 
against the 
cause of defects
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
cause of defects
T
To 
maintain the shape and size 
of the component of 
the timber 
T
To make it 
fit for painting and other treatment
T
For 
effectively gluing and joining
T
To reduce the 
shrinkage, warping, twisting
(shrinkage - becoming less or smaller)
(Warping  - Bend out of shape, as under pressure or from heat)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

50. METHODS OF SEASONING OF TIMBER: Naturalseasoning i
Airseasoning/drying
i
Waterseasoning
Artificialseasoning Airseasoning: Method used
with the timber stacked in the open ai
r. It
requiresthefollowing:
Stacked
stable
and
safely
with
horizontal
spacing
of
at
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Stacked
stable
and
safely
with
horizontal
spacing
of
at
least25mm.
T
Ends of boards sealed by using a suitable sealer
or
cover
topreventtoorapiddryingoutviatheendgrain.
T
The
stack raised well clear of the ground, vegetation, etc
toprovidegoodaircirculationandfreefromrisingdamp,
frost,etc.
T
Over head cover from effects of direct
sunlight and
drivingweather.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

51. AIR SEASONING: T
Thismethod
iseconomical
one
T
Takes
2to4years
T
Coversmorespace
T
Noneedof
skilledlabor
T
Suitable for
cut of sawn planks pieces of wood
not for log
ofwood
Timber
can
stack
either
horizontally
or
vertically
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Timber
can
stack
either
horizontally
or
vertically
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

52. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
AIR SEASONING:
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

53. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
AIR SEASONING:
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

54. WATER SEASONING
T
Log of wood is kept completely immerged in stream of
water
T
Sap, sugar etc are leached out of wood and replaced by
water
T
Then log is
kept out of water after 2 to 4 weeks
and
placedinair
T
Quick
process
and
also
remove
organic
matters
/
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Quick
process
and
also
remove
organic
matters
/
materials
T
Elasticitymayreducedandmaketimberbri
ttle
T
Boiling of timber in water is another rather
quick
process
T
Takeslongtime
tobedriedbutlessthanairseasoning
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

55. ARTIFICIAL SEASONING: T
This is 
quick process of seasoning and moisture content 
can be controlled. 
o
Popular method of artificial seasoning is 
KILN 
SEASONING.
Reason for carrying artificial seasoning are : T
Shrinkage, cracking and warping 
are minimized
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Drying is controlled and no chances for the attack of 
fungi and insects
T
Drying surface is 
even and uniform
T
Reduced duration of seasoning
T
Desired moisture content 
can be attainable
(shrinkage – becoming less or smaller)
(warping - Bend out of shape, as under pressure or from heat)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

56. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

57. KILN SEASONING:
T
This process consists basically of 
introducing heat
. 
T
May be 
directly
, using 
natural gas and/or electricity 
or 
indirectly
, through 
steam-heated heat exchangers, 
although solar energy
is also possible.
T
In the process, deliberate 
control of temperature
, 
relative 
humidity and air circulation 
is provided to give 
conditions at 
various stages (moisture contents or 
times) 
of drying the timber to achieve effective drying. 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
times) 
of drying the timber to achieve effective drying. 
T
Timber is 
stacked in chambers
, called wood drying 
kilns, which are fitted with equipment for 
manipulation 
and control of the temperature 
and the 
relative 
humidity of the drying air and its circulation rate 
through the timber stack.
T
Provides a means of overcoming the limitations imposed 
by 
erratic(inconsistent) weather conditions
. 
T
Almost all commercial timbers of the world are dried in 
industrial kilns.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

58. T
Advantages of conventional kiln drying include higher
throughput and
bettercontrol of the final moisture
content.
T
Conventional kiln and solar drying
both enable wood to be
dried to any moisture content regardless of weather
conditions.
T
For most
large-scale drying operations solar and
conventional kiln drying
are more efficient than airdrying.
T
Compartment-type kilns are most commonly used in timber  companies. 
K
ILN SEASONING
:
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
companies. 
T
A compartment kiln is filled with a static batch of timber
through which air is circulated. In these types of kiln, the
timber remains stationary. Drying conditions are
successively varied from time to time in such a way that the
kilns provide control over the entire charge of timber being
dried.
T
Method is well suited to the needs of timber companies, 
which have to dry timbers of varied species and thickness.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

59. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Kilns are used because the process speeds up seasoning and it
can be used to accurately control the moisture content of the
wood.
T
Woodiscarefully stacked insidethe brick kiln.
T
Water is heated and the resulting steam allowed to enter the
kiln, circulating inside and around the wood boards. Over
time, the amount of steam (humidity) is reduced until the
woodhas the desiredmoisturecontent.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

60. Compartmental kiln T
A compartment kiln is a
single enclosed container or
building,etc.
T
Timber is stacked as described above and the whole
stack is
seasoned using a program of settings until the
whole stack is reduced to the moisture content
required.
Progressive
:
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Progressive
:
T
A progressive kiln has the
stack on trolleys that
‘progressively’ travel through chambers
that change
the conditions as
it travels through the varying
atmospheres.(trolleys -
An wheeled vehicle that runs on rails and is
propelled by electricity)
T
The advantage of this system, although much larger,
has a
continuous flow of seasoned timber coming off
line.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

61. Solar kiln T
A solar kiln is a cross between kiln drying and air drying.
These kilns are generally a
greenhouse with a high-
temperature fan and either vents or a condensing system
.
Solar kilns are slower and variable due to the weather, but
are low cost.
Other seasoningof Timberare
Boiling or Steam seasoning
T
Submersion in boiling water or the application of steam
speed the drying of wood. This method is said to cause less
shrinkage
"
...
but
it
is
expensive
to
use,
and
reduces
the
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
shrinkage
"
...
but
it
is
expensive
to
use,
and
reduces
the
strength and elasticityof the timber."
Chemical or salt seasoning
T
Salt seasoning is the submersion of wood in a solution of
urea, sodium nitrate or sodium chloride
, all of which act as
dehydrating agents. Then the wood is airdried.
Electrical seasoning
T
Electrical seasoning involves running an
electrical current
through the timber causing heat to build up drying the wood
.
Thismethod isexpensive but is fast and uniform quality.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

62. PRESERVATION OF TIMBER:
To prevent the probable defects of timber due to fungi, insects,
alternate heating and cooling timber must be preserved in order to
increase the life span of timber, make durable.
Followingare the various methods of preservation:
Charring: 
T
Very old method, no preservatives are used 
T
Surface to be charred is kept wet for about half an  hour and 
burnt up to 15mm depth over a wood fire
The charred portion is then cooled by water
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
The charred portion is then cooled by water
T
This burnt layer doesn’t affected by moisture, fung i etc
T
Adopted for lower ends of posts for fencing, teleph one etc
(Charring:  Burn to charcoal )
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

63. Tarring : (coating) •Timber surface is coated with hot coal tar with bru shes
•Coal tar has unpleasant smell and appearance 
•Coal tar makes timber unsuitable for painting
•Adopted for frames of doors and windows, rough timber work 
etc
•Coal tar is fire-resistant.
( Tar - It can be produced from
coal
,
wood
,
petroleum
.It is black, 
and a mixture of
hydrocarbons
and free
carbon
. )
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

64. Painting: T
Paints are good preservatives
T
Form thin layer in the surface of timber
T
Thin surface acts as barrier for defective environmental factors
Creosoting:
T
Timber surface coated
with creosote oil
T
Creosote oil is obtained by distillation of tar(distillation - process of
purifying a liquid by boiling it and condensing its vapors)
Steps are:
T
Timber
are
thoroughly
seasoned
and
dried
PRESERVATION OF TIMBER:
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Timber
are
thoroughly
seasoned
and
dried
T
Placed well seasoned wood in air tight chamber
T
Air is pumped out from chamber
T
Creosote oil is then
pumped under high pressure of 0.7-1.0N/mm
2
and
temperature of about 50
0
C
T
After 1 to 2 hrs, when timber has sufficiently
absorbed creosote oil, it
is taken out of chamber
T
Creosote oil is antiseptic or it is poisonous to the wood-attacking fungi
T
Creosote oil: black or brown liquid and weakly affected by water
T
Unpleasant odour and having low wood-penetrating ability to the
extent of 1mm to 2mm only
T
It produces undesirable color in timber
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

65. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

66. Abel’sprocess: T
Timber surface is cleaned and
coated with a dilute
solutionofsodiumsilicate
T
Paste of slaked lime is then applied and finally, a
concentrated solution of
silica soda
is applied on the
timbersurface
T
This
process
is
quite
satisfactory
in
making
the
PRESERVATION OF TIMBER:
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
This
process
is
quite
satisfactory
in
making
the
timberfire-resistant
Fireproofingoftimber:
T
Timber can’t be made fire proof but some
chemical
treatment may reduce the fire attack towards
the
timber
T
Soaking of timber in
ammonium sulphate,
ammonium chloride, zinc chloride
etc improves the
fireresistingcapacityoftimber.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

67. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

68. BAMBOO–(PROPERTIES AND USES) T
Bamboo,
like true wood, is a natural composite material
with
ahigh strength-to-weight ratio useful for structures.
T
In
China and India, bamboo was used to hold up
simple
suspension bridges, either by making cables of split bambooor
twistingof sufficiently pliable(workable)bamboo together.
T
Bamboo has also long been used as scaffolding
; the practice
has been banned in China for buildings over six storeys, but i s
still
in
continuous
use
for
skyscrapers
in
Hong
Kong
.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
still
in
continuous
use
for
skyscrapers
in
Hong
Kong
.
T
In
Japanese architecture, bamboo is used primarily as a
supplemental and/or decorative elemen
t in buildings such as
fencing, fountains, grates and gutters, largely due to the
ready abundance of quality timber.
Notes (Grates - A barrier that has parallel or cross ed bars 
blocking a passage but admitting air.)
(Gutters - A channel along the eaves or on the roof;  collects 
and carries away rainwater )
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

69. T
Can be cut and laminated into sheets and planks(like
board,plyboard).
T
Bamboo intended for use in construction should be
treated to resist insects and rot. The most common
solution for this purpose is a mixture of
borax
and
boric
acid
.
T
Bamboo
has
been
used
as
reinforcement
for
concrete
in
BAMBOO–(PROPERTIES AND USES)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Bamboo
has
been
used
as
reinforcement
for
concrete
in
those areas where it is plentiful, though dispute exists
over its effectiveness in the various studies done on the
subject.
T
Bamboo does have the necessary strength to fulfil this
function, but untreated bamboo will swell with water
absorbed from the concrete, causing it to crack. Several
procedures must be followed to overcome this
shortcoming.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

70. T
Bamboo was treated with borax and boric acid as a fire retardant 
and insecticide and bent in the required shape.  T
The bamboo sections were joined with reinforcement bars and 
concrete mortar to achieve the necessary lengths BAMBOO–(PROPERTIES AND USES)
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

71. WOOD BASED PRODUCTS
1.
Veneers
T
Veneering is the primary process of manufacturing 
woods.
T
Prepared by slicing and sawing of wood in thin sheets of 
0.4mm to 6mm.
T
Are of superior Quality.
T
Used in manufacturing ply woods, battens, 
lamin
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Used in manufacturing ply woods, battens, 
lamin
boards.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

72. 2. Plywood T
Is a manufactured wood panel from the family of
manufactured boards (such as
medium-density
fibreboard
(MDF),
particle board
(chipboard), etc.) made
fromthinsheetsof
woodveneer
.
T
Prepared by gluing together odd number of veneers with
grain direction of core block at right angle to adjacent
veneer
or
ply
.
WOOD BASED PRODUCTS
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
veneer
or
ply
.
T
Are used in making partition, furniture, ceiling, doors,
panelingwall,Formworksforconcrete.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

73. PLYWOOD
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

74. 3. BATTEN BOARD
T
Is a solid block with core of sawn thin wood 
T
The Thickness of core is about 20mm to 25mm
T
Total thickness of board is about 50mm
T
Is Light and strong
T
Do not crack or split easily
T
Uses: partition wall, furniture, shutters, packing case
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
T
Uses: partition wall, furniture, shutters, packing case
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

75. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

76. 4. LAMINBOARD
T
Consist of core of strips each not exceeding 7 mm in 
thickness.
T
These strips are joined together with two face veneers.
T
Laminboard are used for furniture, partition, doors, 
windows, ceilings,etc.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

77. IMPREGTIMBER/IMPREGNATED TIMBER T
Timber which has been made flame-resistant, fungi-
resistant, or insect-proof by forcing into it under 
vacuum or pressure a flame retardant or a fungal or 
insect poison.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

78. COMPREGTIMBER
T
Processed wood whose cellsare impregnated with a resin and 
compressed, to reduce shrinking and swelling and to 
increasedensity and strength.
T
Compreg is a very special wood composite material with 
exquisite mechanical properties.  T
Compreg indicates that it is both impregnated and 
compressed.  T
Used in applications where long durability, hardness, and  dimensional stability is required e.g. gears, rolls  and wear 
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
dimensional stability is required e.g. gears, rolls  and wear  strips of industrial conveyors, woodworking machine tables.
T
Regardless of its hardness, it is comparatively eas y to 
machine, which makes it an excellent choice for 
manufacturers of exclusive woodworking products.
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec

79. Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec
Er. Pramesh Hada, Asst. Professor, civil 
Engineering Department,nec