Flashing a Deck Ledger or Porch Connection

Q. I am replacing my wood deck and installing a treated wood ledger. How can I best flash and connect the ledger to my frame house? Do I remove the siding?

A. Absolutely remove the siding from the installation area at the new ledger. Next remove the siding about 6" to 18" above the ledger for flashing purposes. Now install an Ice & Water Shield or a roofing type waterproof membrane over the bare band joist and up above the location of your new ledger. This membrane protects the house framing and creates a gasket between the existing house structure and any new structure like your new deck.

Next install the new treated lumber deck ledger by through bolting it to & through the band joist of the house. Next apply another membrane from the same height of the existing flashing over the new deck ledger, applied to follow the form of the ledger much as wall paper would be applied. Then install your (treated lumber approved type) joist hangers for your new deck joists over the membrane flashings with stainless steel fasteners or other approved fasteners for treated lumber. If you like you can then install an aluminum brake metal counter flashing Z-trim or L-trim over the new floor joists.

This system provides a great water seal and separation between the deck and the house.

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