Water flowing behind flashing and entering basement

Originally Posted By: John Green
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Folks,


I could use some advice. We bought a very nice custom 4 year/old custom home a year ago. Whenever it rains, I've noticed some water dripping into the basement from over a basement window. After some heavy rains, I've discovered that the top of the foundation wall is flooded with water and dripping down the interior walls. After the rains stopped, I inspected outside and discovered that there is water flowing between the foundation wall and the flashing for the deck. So there's flowing water behind the flashing, not good. Here's a view from under the deck.



Here's another view looking straight-up at the flashing from the bottom. The dark stuff behind the flashing is water-soaked OSB. The white stuff you see is evidently mold.



The places where the water is leaking seems to be over two sets of sliding glass doors that lead from the house onto the deck. Here's what they look like from the top of the deck.


My guess is that this water is getting sucked under the sill, and entering the basement this way. Needless to say, I'm a little freaked out. Can anybody hazard a guess as to how water is getting behind the flashing and into the basement? And even more important, what do I do now? Many thanks!

John


Originally Posted By: rcloyd
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John:


Properly installed deck flashing would not allow water to get between the deck ledger board and the wall of the house. I bet your flashing is installed improperly.


Regards,


--
Russell G. Cloyd
Intra-Spec Home Inspections
& Code Consulting, LLC
859-586-4591
www.intra-spechomeinspections.com

Originally Posted By: John Green
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Russell,


Thanks for the reply. Would a bad deck ledger flashing cause water to get behind the flashing? The wall sheathing is soaked behind the flashing.

Since the water leaks are mainly located under the sliding doors out to the deck from the house, I'm wondering if perhaps the sliders themselves are not flashed correctly. Any thoughts about that?

Also, what's my next step here? This is a pretty huge deck. Would it have to be torn down to fix it? Since there is wet sheathing and signs of mold, I'm pretty worried about the size ($$$) of the project to fix it.

BTW, we had a home inspection done before we bought the house, and they didn't note any problems with flashings. I'm thinking of calling up the home inspection company and asking if they'll come out and look at the damage. Is there any other profession advice I should seek?


Originally Posted By: psisler
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John,


I agree with Russell on his explanation. I inspect the exterior of the home first. One of the first things I check is the deck, as I also own a Deck Business. The deck flashing is similar to Z bar used in siding applications only bigger. When the flashing is installed under door thresholds there those that cut out the high end under the door to allow the threshold to lay flat. Most of the time, that I have seen, in failed flashing, is that they fail to seal this area and you get leaks. This area must be sealed to prevent this from happening. Have your deck inspected again by a qualified/licensed contractor for diagnosis.


Patrick


Originally Posted By: chorne
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Hi,


The deck flashing should not be behind the ledger. Proper
installation is behind the siding above the deck and out onto
the top of the ledger and the joists. (6" +-)
the installation under the sliders should be on the sill under
the threshold and down to the ledger and out as the other
areas. There should be sealer between the threshold and
the flashing when the slider is installed.

It is correctable and should be done sooner than later.

Carla


Originally Posted By: John Green
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Thanks, Patrick and Carla. Your explanations make a lot of sense. I wonder how they’ll be able to inspect the flashing under the sliders without taking the door assemblies out. Perhaps the siding could be removed and the frames pulled out? Does anybody know? My biggest fear is having to tear down the deck to pull the ledger board. This is a very large and high deck.


BTW, Carla. It seems that flashing behind the ledger board is an acceptable practice IF you also use Z flashing in conjunction with it. Here's a diagram linked from www.decks.com.

![](upload://AjTKfZdtUwjukWlr4NwJeCVf89U.jpeg)

Here's the reference, interesting reading: http://www.decks.com/articles.aspx?articleid=28

I guess I'll have to find a contractor to make an assessment. This is all very annoying because this is a very expensive and recently built home. I'll keep ya'll informed if you're interested.

Thanks again, and best regards,
John


Originally Posted By: chorne
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The z flashing will prevent water from penetrating,


the flashing behind the ledger does nothing.


The only reason that you would have to remove the
deck ledger is if there is moisture damage behind it.

Carla


Originally Posted By: John Green
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Thanks again, Carla. I guess in the pictured application the flashing behind the ledger is used to divert water over the siding below the deck. On my deck the flashing actually covers the lower few inches of sheathing that would otherwise be exposed under my deck. I’m sure there are examples where it would be superfluous however.


The OSB sheathing behind my ledger is definitely wet under the sliding doors areas. I'm thinking if I can solve the sliding door flashing problem, and install Z flashing on the deck, the OSB behind the ledger will eventually dry out and the problem will be solved. At least that's my current theory. Thanks again. Ya'll are a great bunch of folks.


Originally Posted By: dvalley
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John,


I've done many new construction inspections and 40% of the time I will find improperly flashed ledger boards. I've seen flashing installed right behind the ledger many times and I've also seen flashing tucked under the siding but bent outward above the ledger but right over the walkboards.

Carla has definitely answered your question correctly. If there were a Z flashing installed and it was tucked and brought right out over the ledger (but under the walkboards) it would be impossible for water to enter the sill area.

If the existing damage to the rim board is not serious, you may be able to correct the flashing by removing the walkboard on top of the ledger and depending on your siding, you may be able to tuck it properly.

Good Luck.


--
David Valley
MAB Member

Massachusetts Certified Home Inspections
http://www.masscertified.com

"Some cause happiness wherever they go; others, whenever they go."

Originally Posted By: John Green
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David,


Thanks for the reply. Unfortunately, I think you and Carla are missing the point. As I've stated, the water is flowing behind the flashing. Why would making it a Z flashing change that? I need to find out why the water is getting behind the flashing. I believe that Patrick probably has it correct that the flashing under the sliders has been incorrectly cut or sealed. That could create a channel for water to get behind the flashing and reach my sill area.

I do agree that the lack of Z flashing is another problem that should be addressed as well, and I appreciate you folks pointing it out. However, I fail to see how that has any impact on my problem of water getting into the basement.