Galvanized Flat Washer

A galvanized flat washer sits under the nut or eye of cabling and bracing hardware to spread the load over the wood. The galvanized finish holds up outdoors, which matters for hardware that stays in a tree for years.

What washers do in cabling

Through hardware needs something between the nut or eye and the tree. A washer spreads the clamping load so the nut does not crush into the bark and wood. On rounded stems, many installers use a beveled or curved washer where it seats better, and a flat washer where the surface allows.

Match the washer's hole to the hardware diameter. A washer with an oversized hole lets the nut pull into it and defeats the point.

Buy washers in quantity, since every through-bolt anchor needs at least one and they are easy to drop. Keeping a jar of matched washers and nuts for each hardware size in the cabling kit saves a lot of searching and makes sure the right parts go in the tree.

Install and inspect

Seat the washer against the bark without cutting away more than needed, and snug the nut firmly. Mixed metals can corrode, so keep to galvanized hardware throughout the system. Check washers and nuts at each inspection for rust, loosening and wood growth over the hardware. Cabling and bracing is structural work on a living tree. It should be specified and installed by a trained arborist following ANSI A300 Part 3, ANSI Z133 and the hardware maker's instructions, and inspected on a regular schedule after install. See more in our cabling hardware section.