Decks, Patios, Porches and Docks - Ledger board waterproofing

I am connecting a deck to a concrete patio. I poured a 10” x 10’ x 32” footer on the corner of the patio, to stop a settling problem. I placed ½” L bolts in the footer and have a 2x4 pressure treated board the ledger will sit on as well as being screwed to the deck with lag screws. The ledger will be 2 2x10’s with ½ “ plywood sandwiched. Besides using a spacer between the patio and the ledger what is the best way to place a moisture barrier?

Why not use good old builders felt (40lb tar paper)? It's cheaper than ice an water shield and provides an excellent water block. I tore off 20 year old masonite clapboards from my house a couple of years back, as well as a ledger I had put up 15 + years ago. Both had builders felt behind them and I had zero water related issues where the paper wes installed.

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http://www.protectowrap.com/cat_enerplatelinr.php

They make other waterproofing materials as well.