Why Building Design needs creative thinking

DEFECTS IN TIMBER

 You have understood the tree, its classification and structure. Now let us study the Defects in timber. As hum body has many defects, timber also have defects. These are grouped into the following five divisions:

1) Defects due to conversion

2) Defects due to fungi

3) Defects due to insects.

 4) Defects due tonatural forces

5) Defects due to seasoning Now,

 let us know various types of defects under each category:

Defects due to Conversion, During the process of converting timber to Commercial form, the following defects may occur:

i) Chip mark

ii) Diagonal grain iii) Tom grain

iV) Wane:

This defect is indicated by the marks or signs placed by chips on the finished surface bf timber. They may also be formed by the parts of a running machine. Diagonal Grain: This defect is formed due to improper sawing of timber. It is indicated by diagonal mark on straight grained surface of timber. Tom Glain: This defect is caused when a small depression is formed on the finished surface of timber by falling of a tool or so. Wane: This defect is denoted by the presence of original rounded surface on the manufactured piece of timber.

Defects due to Fungi Fungi ate minute microscopic plant organisms. They attack timber only when the following two conditions are satisfied simultaneously.

i) The moisture content of timber

ii) There is presence of air and warmth for the growth of fungi. If any of the above condition is assert, decay of wood due to fungi would not occur. Hence, &y wood having moisture content less than 12-1496 will remain sound for centuries. Similarly, wood submerged in water win not be attacked by fungi because of absence of air. Following defects are caused in timber by fungi i)i Blue stain ii) Brown rot

 iii) Dry rot

iv) Heart rot

v) Sapstain

vi) Wet rot has twisted out of shape; it is said to have warped.

This will be upadated soon as possible