What taper is recommended for a plywood scarf patch?

The recommended taper for a plywood scarf patch is 12:1. This taper ratio means that for every 12 units of horizontal distance, the patch will taper down 1 unit in vertical thickness. This gradual transition helps to distribute stress more evenly over the joint, minimizing the risk of failure at the repair site. A 12:1 taper provides sufficient surface area for glue bonding, which is critical in maintaining the structural integrity of the repair.

Using a taper that is too steep (like 8:1 or 10:1) could lead to a concentrated stress point, while a taper that is too shallow (like 15:1) may not adequately support the load and could result in a weak bond. Therefore, the 12:1 taper strikes an optimal balance, ensuring strength and durability in the repair.