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Discussion Starter · #1 ·
I just bought this house and we had a lot of rain today. We are getting a little water in the basement and I saw it's coming in through the top of the foundation wall and is even getting the floor joists wet.
I checked outside and found that the water seems to be coming in where the deck mounts to the outside wall. I have attached a couple of photos. As you can see, there is flashing at the top of the ledger board but there is no flashing underneath, and there is a gap between the ledger board and the top of the foundation with foam board exposed. Is there a simple way to fix this? Can I just caulk on the top side between the first deck board and the sliding door / siding?

Thanks!
 

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No, you can't just caulk it to fix it.
Can you take a few more shots, back a little so you can see the joist/ledger relationship. It seems odd that the joist sits so much higher then the ledger. Also take some photos of the interior where the water is coming into the basement wall.
The flashing that goes behind the ledger ,should go over the top and slightly shoot out over the top so the water keeps away from the wood.
Ron
 

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Discussion Starter · #3 ·
No, you can't just caulk it to fix it.
Can you take a few more shots, back a little so you can see the joist/ledger relationship. It seems odd that the joist sits so much higher then the ledger. Also take some photos of the interior where the water is coming into the basement wall.
The flashing that goes behind the ledger ,should go over the top and slightly shoot out over the top so the water keeps away from the wood.
Ron
Ron,
Here are a few more. 1118 & 1120 show the interior. Notice in 1127 the flashing going under the first deck board and 1126 is panned out a bit to show more from under the deck. Thanks for your quick reply!
 

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Discussion Starter · #4 ·
Ron,
One more thing. What you're seeing in the photo behind and extending below the ledger board is foam board not flashing. The only flashing I can see is up at the top. Maybe stuffing some flashing strip between the ledger board and the foam board so that the flashing extends beyond the top of the foundation wall? Of course that would only help if water is not running behind the ledger. Just thinking out loud.
 

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You would need to remove the deck board closest to the house. Install a "Z" flashing that would go up under the siding, lay on the ledger and drop down on the face of the ledger. The last 1/4" would kick out so the water would drip away from the wood ledger.
Then reinstall the deck board. Don't put any holes in the flashing.
Ron
 

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Discussion Starter · #6 ·
Sounds good. Should I be concerned with the exposed foam board? The bottom of the foam is about flush with the top of the foundation wall.
 

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Sounds good. Should I be concerned with the exposed foam board? The bottom of the foam is about flush with the top of the foundation wall.
The foamboard should not be behind the ledger as it creates a non solid space. The ledger cannot be secured against the house with the foam behind it. It creates a sort of shear plane where the weight of the deck can/will drop the ledger down due to the space.
Ron
 

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Is that flashing in the red circle? It looks like there is already flashing installed. The two joist on either end do not hang from the ledger but are installed at the ends of the ledger. So they cut the flashing and folded it on top of the joist. Not a perfect install, but it should be somewhat functional. I am curious if the flashing goes up behind the siding.
 

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Discussion Starter · #9 ·
Yes that is flashing you circled but I don't think it goes up behind the siding. If it ever quits raining long enough I will pull up the first board and assess the situation.

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Discussion Starter · #11 ·
Hi you ever find out what the issue was?
Thanks
Unfortunately not. I tried pulling the first deck board out but it wouldn't budge. My guess is perhaps construction adhesive or something like that was used where the first board slips under the sliding glass door. I had a guy come look at it and he couldn't get it out either (without committing to a demolition project). He noticed the J channel above my sliding glass door wasn't done right so he fixed that. He thought that combined with the fact that the sheathing is foam board and not OSB or plywood was causing water to get in around the flange of the sliding door. None of that fixed it. Thankfully, the last few years have not been overly wet. Otherwise I would be in bad shape.
 

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if the deck board wil not come up check for screws that have missing heads. sometimes deck screws, when set with a screw gun, pop the heads off and the body still holds the boards down. You may have to get rough with it to remove it.

I just noticed something in the last picture in post 3. Is that metal flashing I see poking out under the deck board near the spindle. If so, something is definatly goofy with the flashing
 

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Discussion Starter · #13 · (Edited)
if the deck board wil not come up check for screws that have missing heads. sometimes deck screws, when set with a screw gun, pop the heads off and the body still holds the boards down. You may have to get rough with it to remove it.

I just noticed something in the last picture in post 3. Is that metal flashing I see poking out under the deck board near the spindle. If so, something is definatly goofy with the flashing
I thought of that too. I verified I had all the screws out that were visible. That said, part of that first board is set back under the threshold of the sliding door and under the siding J channel on either side of the door. My only option then would be pulling the door to see what's under it.

Yes, that is flashing sticking out under the deck board.
 

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I doubt you will have to pull the door right now, hopefully never. However, vinyl siding is easy to remove and replace. It may be time to pull the piece covering the area just above the deck to see if the flashing comes up the wall
 

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I saw leaks like this on buildings in a condo project. The problem was the nails / screws in the board against the wall were angled toward the wall missing the ledger and puncturing the flashing behind the ledger. It doesn't matter much if flashing is right or wrong then, the water follows the fastener hole in.
 

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It’s defiantly time to pull that first coarse of siding and the decking against the house to see what’s going on. This is a very common issue and should be easy to figure out once exposed.

I doubt the slider has a pan flashing detail under it and it should so the door may have to come out also. Removing the decking against the house should answer that question.

OP said that he and someone else tried to remove the decking and could not and thought it may be glued. Gluing the board would be unusual but if it was glued to the rim that could be the, or part of the cause of the leak. Either way the board needs to come up even if it’s in pieces.

This thread is three years old, ignoring the issue any longer could be costly.
 

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Discussion Starter · #17 ·
I doubt you will have to pull the door right now, hopefully never. However, vinyl siding is easy to remove and replace. It may be time to pull the piece covering the area just above the deck to see if the flashing comes up the wall
That's the other thing. There is no space between the sliding glass door and the deck. The threshold sits right on the first deck board.
 

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Similar Issue

I'm pretty much having this same issue with my deck. The bummer is that it's a two tier deck and both the upper and lower part were constructed the same way. We've tried various attempts to stop water leakage over the years and we've had some success limiting the water flow.

This past summer we had a ton of rain and I recently noticed that white mold is now growing in my crawl space where water is still leaking in from the lower deck.

I'm planning to install z flashing on top and below, but I was wondering how to stop water from getting in where the end of the deck meets the end of the house. In other words, where the decking and ledger meet the corner of my home (the outside corner post of the siding).

Picture attached for reference. We obviously used some caulk here, but I'm referring to the gaps where the siding and the boards don't meet up exactly. How do we stop water from getting in there?
 

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I was living with my now ex g/f and had the same exact problem and because I'm hypersensitive to mold and wooden decks are known to get moldy I completely tore the deck apart and sealed the side of the house. Once that was done whatever joists were moldy I tossed and primered and painted the remaining joists. It was allot of work but when I was done I didn't have any more problems with water intrusion and the deck actually looked better
 
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