Timber is a form of wood categorized into endogenous and exogenous trees, with exogenous trees being more commonly used in construction. They are divided into softwood from conifers and hardwood from deciduous trees, each with distinct characteristics. Seasoning timber is essential to remove moisture and prevent decay, and it is utilized in various applications including construction, furniture, and agricultural tools.

1. TIMBER

2. Timber is a form of wood .it is used for building or engineering
purposes.All trees are divided in to 2 groups based on their mode of
growth.
1) Endogenous : These trees grow by the formation of layers
of new wood crossing & penetrating the fibres of the
wood previousy formed,eg.Bamboo,coconut,etc..
2) Exogenous :It grow outwards by the addition of rings of
young wood.,eg.Teak,sal,etc..

3. • The c/s of exogenous trees shows distinct concentric rings called
annual rings.the timber is an exogenous trees are mainly used in
engineering works.these are sub divided in to
i. Conifers or evergreen trees which yield soft wood,.
eg:pine,deodar,etc..
ii. Deciduous Broad leaf trees which yield hard wood,.
eg:Teak,sal ,etc..

4. characteristics of hard timber
 heavy in weight.
 Dark in colour
 Durable
 It doesn’t show clear annual rings
 It is strong
 It is non resinous

5. characteristics of soft timber
 light in weight
 It is light in color
 It is resinous
 It has straight fibres
 It has distinct annual rings
 It is comparatively weak
 It can be split easily.

6. structure of an exogenous tree

7. 1. Pith: It is the inner most part of the tree.it consist of cellular tissues.
It varies in shape and size
2. Heart Wood: is the inner annual rings surrounding pith. It is strong
and dark in color. This portion is useful for several engineering
purpose.
3. Sap Wood: This portion containing the outer annual rings b/n the
cambium layer & the heart wood.light in color .it cannot be used for
any engineering work, because it contains large amount of moisture
and is liable to decay quickly

8. 4. Cambium Layer: It is the soft ring surrounding the outermost ring of
sapwood
5. Inner Bark: It is a inner skin of tree . It provides protection to
cambium layer.
6. Outer Bark: It is the outer skin of the tree and contain of wood fibres.
Sometimes it contains cracks and fissures.
7. Medullary Rays: These are thin radial fibers extending from pith to
cambium layer

9. SEASONING OF TIMBER
A newly cut trees contains water about 50% of its
own dry weight in the form of moisture &
sap.The moisture content is lead to decay of
timber. There for the water is removed soon
before applied for its purpose. This process of
removal of moisture is known as seasoning of
timber

10. METHODS OF SEASONING
 Natural seasoning
 Artificial seasoning

11. NATURAL SEASONING OR AIR SEASONING
It is a natural method by placing the timber under a
shelter.They are allowed to get free circulation of air for a
period of 2 to 4 years
ARTIFICIAL SEASONING
1.Boiling
2.Chemical seasoning
3.Electrical seasoning
4.Kiln seasoning
5.Water seasoning

12. DEFECTS IN TIMBER
KNOT is a type of weakness.it is present on the
surface of wood in the form of hard dark pieces.it
doesn’t carry compression.they are called nail
knots
• The diameter is less than 6mm diameter,small knots.
• The diameter is b/n 6 to 20mm diameter, medium
knots.
• The diameter is b/n 20 to 40mm diameter,large
knots.
• The diameter is more than 40mm diameter,that is
tight knots & loose knots.

14. SHAKE
SHAKE is a complete or incomplete separation b/n adjoining layers of
tissues.They can be cup shakes,heart shakes,radial shakes,ring shakes..
Cup shake –curved split, it separates the annual ring from the next.

15. HEART SHAKE: the split is radiate From
the center.

18. PROPERTIES OF WOOD
• Colour and odur
• Specific gravity
• Moisture content
• Shrinkage and swelling
• Strength

19. USES OF TIMBER
• It is used for door and window frames,shutters of doors and windows ,
roofing materials ,etc
• It is used for formwork of cement concrete, centering of an arch,etc..
• It is used for making railway coach wagons,sleepers
• It is used for temporary bridges & boat construction
• Making furniture,agricultural instruments,musical instruments

20. THANK YOU