Self-sealing Attach-A-Deck spacers are a plunger-and-cup setup
So that water doesn’t get trapped behind a deck ledger and leak into the floor-framing system, many builders like to space the ledger off the wall using stacks of washers, plastic spacers, or wood blocks. But codes dictate that these solutions can’t be thicker than 1⁄2 in., which isn’t deep enough to accommodate siding. Rather than cutting back the siding and integrating flashing, consider using self-sealing Attach-A-Deck spacers. These spacers are 2 in. deep, so they can handle siding up to 1-1⁄2 in. thick and still leave a 1⁄2-in. airspace. They also eliminate fussy flashing details.
Attach-A-Deck spacers are a plunger-and-cup setup. You fill the plastic cup with sealant before screwing or bolting the ledger onto the wall, and as the plunger is tightened down, sealant squeezes out to seal the perimeter and the siding hole. It’s ingenious.
The devices are sold and installed in pairs ($9) spaced 2 in. down from the top and 2 in. up from the bottom of the ledger. As an example, a deck 12 ft. deep (house to beam) and 16 ft. long (length of ledger) will need 11 pairs. Attach-A-Deck is more economical than other methods of ledger mounting when you figure the time you save removing siding, not to mention the savings on flashing and peel-and-stick membrane.
For more details and full how-to information on installing this product, visit FineHomebuilding.com/deckblog.