How to choose the right thickness for a chair backrest panel
A thicker panel is not automatically a stronger one. Ply count, form depth and fixing points have to be considered together.
Thickness on a chair backrest panel is usually chosen on the assumption that thicker means better. In reality thickness alone does not determine strength — ply count, ply orientation and the depth of the form matter just as much.
Where 8 mm is enough for a shallow backrest, dropping below 12 mm becomes risky on a deep form designed to support leaning back. On a seat panel, where the load comes straight down, increasing the ply count is more effective than increasing thickness.
Fixing points deserve their own attention: the area around a screw seat is the weakest part of the panel. Keeping the ply count intact there is far safer than thinning it along the edge.