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I am having an existing deck/porch that is attached to my home repaired/replaced due to termite and water damage. I told the guys to replace any damaged wood they thought necessary. The replaced the ledger, but after the fact I realize there should have been some type of water shedding(tyvek) underlayment behind it. But it's too late now its done. Going forward, looking for best ideas to flash the ledger so water will not seep in and rot it again. Here are things I thought of. The lumber is PT for ground.

  1. Spray whole board with rainguard(its on order).
  2. Caulk/fill seams on top bottom with some type of roof sealant(henrys/gaco roof)
  3. Fashion/Shape a piece of joist tape(i have imus butyl 4/5 inch) into the top like a metal L flashing.
  4. Put Z metal flashing over that sealed with Loctite joint and seam and screws.
  5. Paint over with liquid rubber/mesh.

Now, some of the steps may or can be eliminated like step 5, but it seems like a good idea.

The thing I am thinking about is the metal flashing.

Should I use vinyl, or use some type of "copper" tape that they sell?enter image description here

I have attached pictures.enter image description here

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Update:

Thanks for all answers. I basically am "duplicating" protection as its only a 20 ft run of PT. My decisions: 1. fill the crack between the ledger and house(plaster) with filler rope and through the roof sealant, which I have used before. I like it. Clear and dries like urethane or something.
2 Paint the ledger with GACO roof tape(similar to liquid rubber but silicon) 3. Install plastic Z flashing over ledger sticking on with loctite roof cement, and then seal the seam on top with mesh and the GACO. (I had to order a case of 40 plastic Z flashings online..I COULD not find anything in stock anywhere in the universe, including the big box stores...they are all out, and have no idea about shipments. Their is a big time shortage of certain items right now....I figure I will be able to sell the extra on craigslist, since I had to pay $200 for a case. I only need probably 5. But I could not waste any more time searching for the items...crazy.

Update 3/29 Here is my final solution. Caulk the gap between the ledger and house with through the roof. Add strip of 3" 3M flashing tape over that(since I had it)...install metal z flashing and glue with liquid nails fuze it max...eventually I will just paint over before decking is installed. I think its pretty secure at this point. enter image description here

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Update : Another use for 3M flashing tape...around edges of plywood sheathing flat roof. My underlayment will go over this..then my drip edge. enter image description here

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Typically, an aluminum or galvanized "z flashing" as you called it, would be installed under the siding, over the top of the ledger and down the upper lip a little. Decking is installed on top of this flashing.

(Diagram not to scale)

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Done this way there is no need for any of the other products you mentioned unless you have moisture or insect concerns from below the ledger.

I would not use vinyl or copper tape for this, any cracks will prevent it from working properly so it needs to be very durable.

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  • Thanks..if u notice..my siding is tongue and groove...so no siding is available to overlap the flashing....so thats why i was thinking about the liquid rubber or something...also do u recommend a flashing on the bottom of the ledger...i have seen that in pictures. thanks Mar 11 at 0:25
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If the new ledger is pressure-treated, you shouldn't have to worry too much about it rotting any time soon. Butt the deck boards up against your masonry foundation wall and run a good bead of exterior caulk along there, like this:

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  • Thanks. I basically am "duplicating" protection as its only a 20 ft run of PT. My decisions: 1. fill the crack between the ledger and house(plaster) with filler rope and through the roof sealant, which I have used before. I like it. Clear and dries like urethane or something. 2 Mar 13 at 16:28
  • Thanks I used to think that but I guess even PT will rot sooner or later if it gets wet and cannot get dry. That said, I have some PT on part of the deck that was repaired 10 years ago or so, and it still looks good to me.. when we totally stripped off the old decking, I was able to see it. Mar 13 at 16:39
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Get a sheet metal break and a roll of trim coil.

Looks like a double change of plane; custom will be the only option. Do you have the plastic flashing yet? Pic of a deck board sitting on one, in place? And unless you can get the bottom piece of siding off, you'll need a strip of flashing for the flashing....

Do the top, the bottom, and caulk all the bolts. Note where it crosses a joist, you cut a tab and bend it back flat. Using a ten foot long sheet metal break, there will be a single seam for a 20' span, instead of however many with the plastic.

Maybe you could stack two of them but I'd need the dimensions of what you bought and that of the space we're working with. And whether or not you're able or willing to pull siding.

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