Can I notch the pile like a wood pile to attach a beam?
The notching of the pile to a 3 or 4 inch depth will not affect the durability or reduce the load bearing capacity, but I would be concerned about the wood deteriorating where the load is applied. If this is for a residential dock and light duty, that load will not be of a concern to me, but for a design load of 40 psf, the wood might deteriorate over time (a few years). The best bet when notching the pile is to place a ΒΌ” stainless plate under the wood to distribute the load on the wood.
