Average seasoned timber

Common seasoned timber

Well seasoned timber

Moderate seasoned timber

Quality of the cells

Thickness of the cells

Structure of the cells

Direction of the cells

Types of cells

Cells structure

Cells thickness

Cells size and quality

For strength

For finishing

For prevent rail twisting

Supporting joint

Covering with copper sheets

Covering with steel sheets

Covering with mild steel sheets

Covering with carbon steel sheets