Slide 50 of 67
- Now letís talk about plywood
- As we discussed earlier in this course, plywood sheathing was shown in the Northridge earthquake to hold up the best.
- What is plywood?
- Plywood is a panel of laminated veneers (plies) constructed in an odd number of layers.
- Layers may consist of one or more plies laminated with parallel grain direction.
- Each layer is positioned perpendicular to the adjacent layer to equalize strain, reduce splitting, and minimize warping.
- Outer layers generally have the outer layers oriented parallel to the long dimension of the panel.
- Plywood must have a minimum number of plies and layers for each thickness range.
For example, 15/32 inch Structural 1 plywood must have at least 4 plies and 3 layers. Non-Structural 1 plywood of the same thickness can have 3 plies
- Construction of plywood
- Top is least effective, bottom is most effective
- Important to have more plys to cover the seams
- 4 or 5 ply work the best