‘Plywood is stronger than timber’

Justify the term ‘Plywood is stronger than timber’.

Ans-: 

 1. Timber has good bending strength across the length of the member where as it has poor bending strength across the width of member. Plywood has good bending strength across the width & length. In other words, plywood is stronger than the solid wood as it has equal strengths in both directions.

2. Timber has poor screw holding strength along the length of member. i.e. if the screw is fitted parallel to the fibers, it virtually does not hold. Across the plane of the plywood, the screw holding strength is very good and, it is fairly good along the plane of the plywood.

3. Effect of moisture is severe in case of unseasoned timber and results in bending, warping, twisting and splitting etc. In seasoned timber this effect is less, but is not totally controlled. Virtually there is no moisture effect on plywood unless the plywood has direct contact with water. The transfer of moisture between the plywood and atmosphere is almost negligible. In other words it is more stable to atmospheric changes as compared to timber.

4. The plywood is available in larger widths. Hence there are lesser joints in plywood structures. But, similar structure in timber would warrant more joints.

            These are the reasons why plywood is stronger than timber.