TIMBER AND TIMBER PRODUCTS

Specific Objectives

Objectives

By the end of the sub-module unit, the trainee should be able to: explain the mode of growth and cellular structure of a tree explain the various methods of conversion and seasoning of timber identify and classify commercial timbers explain timber defects and their effects on strength of timber describe the methods of stress grading explain the preservation of timber describe the manufacture of timber products compare timber with other materials as construction materials describe various tests carried on timber

Content

Key points

Tree - growth - endogens - exogens - cross section of exogenous tree - cellular structure of soft and hard wood Conversion - methods - purposes Seasoning - methods - purposes Classification of timber Defects and their effects on strength of timber - growth defects - conversion defects - seasoning defects - effects on strength Stress grading methods - purpose - method Preservation of timber - reasons - methods Products (manufactured boards - plywood - block boards - chipboard Comparison of timber with other materials Tests carried out on timber Tensile Compression - cleavage - density - moisture content

Specific Objectives

Objectives

By the end of the sub-module unit, the trainee should be able to: select timber for a given task carry out tests on timber

Content

Key points

Selection of timber - hardwood /softwood - cross section Tests on timber - tensile - compression - cleavage - density - moisture content

Competences

Competencies

Ability to: Identify the various sizes of timber Identify defects on timber

Suggested Teaching/Learning Resources

Reading

Textbooks Samples of timber Field visit

Suggested Learning Activities

Activity

Discussion Lectures

Suggested Assessment Methods

Assessment

Oral Written tests Observation

UNIT LESSON

1. Tree
2. Conversion
3. Seasoning
4. Classification of timber
5. Defects and their effects on strength of timber
6. Stress grading methods
7. Preservation of timber
8. Products (manufactured boards
9. Comparison of timber with other materials
10. Tests carried out on timber
11. Tensile
12. Compression