Waterproofing Over Deck Joist

Discussion in 'Decks & Patios' started by Scratch3386, Aug 11, 2012.

  1. Aug 11, 2012 #1

    Scratch3386

    Scratch3386

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    THE BACKGROUND:

    Earlier this year I hired a highly-rated local company to refurbish my aging second story wooden deck. It's on the large side: 28' x 40'. The project involved replacement wood decking and railing up top, and underdecking below, with the original deck supports and wooden joists left intact.

    Unfortunately the decking crew and the underdecking crew were separate -- as it turned out the decking crew were (allegedly) not informed that underdecking was going to be done as well. The redecking was done quickly and well. The underdecking crew, however, had to remove and reinstall the vinyl soffit four times before it finally all fit together correctly and was allegedly watertight.

    THE PROBLEM:

    The big problem is that since the job was completed in early June the underdecking has leaked - persistently - at the double beam that runs parallel to the house right at mid-deck. I want to partially enclose underneath the deck - have already had concrete laid down - and install lighting and outlets there as well. With water leaking, this is obviously not a good idea.

    The company owner has had his 'best guy' come out 4 times now attempting to caulk underneath, and also caulk between the deck boards above the beam (unsightly IMO) in an attempt to redirect the rain water away from the joist. These efforts have not fixed the problem. This 'best guy' (who's part of the abovementioned deck crew) has repeatedly told me that had they known the job also involved underdecking, the deck crew would've taken extra steps to waterproof the beam area FROM ABOVE, BEFORE they installed the new deck boards.

    I just had the company owner to my house again and he's beginning to mumblemouth me about this has never happened before; they don't actually warranty against leaking joists; etc. I've told him straight up that I consider the fault to be on him and his crew for one hand not knowing what the other was doing. I've relayed to him the comments from his 'best guy' and that's when the mumbling started.

    THE FIX?

    What I want is the deck boards directly over the leaking beam to be pulled up (had they used screws instead of nails it'd be easier), and flashing, soffit, and/or other waterproofing materials installed over the joist FROM ABOVE as needed.

    The company owner's opinion is that this won't solve the problem. From my experience many years ago doing roofing, I however believe it will.

    Opinions?
     
    Last edited: Aug 24, 2012
  2. Aug 11, 2012 #2

    nealtw

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    I have never herd of anyone putting soffet under a deck that wasn't covered with a water tight membrane.
     
  3. Aug 12, 2012 #3

    oldognewtrick

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    I'd really like to see pics if you can post them.

    Oh, yeah :welcome: to House Repair Talk!
     
  4. Aug 12, 2012 #4

    Scratch3386

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    Thanks for the welcome. Here are photos, as requested.

    The deck from above:

    [​IMG]

    The caulking attempts on the surface deck boards:

    [​IMG]

    The underdecking, with gutters & downspouts:

    [​IMG]
     
  5. Aug 12, 2012 #5

    Scratch3386

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    And the problematic center joist (beam, actually):

    [​IMG]
     
    Last edited: Aug 13, 2012
  6. Aug 13, 2012 #6

    Scratch3386

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    *TEST* My subsequent posts appear to be held up in Moderation.

    (Edit: ah, there they are)
     
    Last edited: Aug 13, 2012
  7. Aug 13, 2012 #7

    Scratch3386

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    ***deleted***
     
  8. Aug 14, 2012 #8

    nealtw

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    I know you came for answers but i think you're going to get more questions.
    What is supposed to stop the water from entering the deck? How does the water get out from between the boards? Why would you not use vented soffet?
     
  9. Aug 14, 2012 #9

    oldognewtrick

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    Neal, the third pic in the first set shows a gutter running along the beam. I think the soffit is suppose to dump water into the gutter. I'm baffled as to why they used vinyl soffit material and didn't instead use something like bi-rib metal roofing panels?
     
  10. Aug 14, 2012 #10

    nealtw

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    It's interesting and new to me, and how do you clean the gutters?
     
  11. Aug 14, 2012 #11

    oldognewtrick

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    I think at this point, thats the least of his problems...
     
  12. Aug 14, 2012 #12

    nealtw

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    The idea is neat, if I can say neat, but if they just chalked between the boards over the joists, failure is garrenteed this year or some time down the road. The water will stick to the joists until it runs into the beam. I would like to see pictures before they put the deck boards on and before they put the soffet up.
    Sorry Scrach, I'm no help here but I like the look, I'am not sure how someone would expect it to work.
     
  13. Aug 14, 2012 #13

    Scratch3386

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    Nothing stops the water from entering the deck. The vinyl underdecking system catches the water and uses gutters and downspouts to drain it.

    http://www.marylanddeckandshed.com/under-decking.html

    It's meant to keep the finished concrete I had poured at ground level dry - and therefore more useful.

    If/when I can resolve the leaking beam problem I intend to enclose partially underneath and use it for motorcycle garage, workspace and storage.
     
    Last edited: Aug 14, 2012
  14. Aug 14, 2012 #14

    Scratch3386

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    The whole underdecking works fine except for that beam. That's where the leak is occurring, because the two crews didn't communicate and the beam wasn't properly covered.
     
  15. Aug 14, 2012 #15

    nealtw

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    What were they supposed to do?
     
  16. Aug 14, 2012 #16

    Scratch3386

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    That's the point of my thread. I was hoping someone here with more direct knowledge/experience in decks and underdecking than myself would be able to advise me.
     
  17. Aug 14, 2012 #17

    joecaption

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    http://www.underdeck.com/

    For anyone who has not seen this done before, the O/P has a system like this installed.
    It looks like soffit, but it's not.
    I would have installed a piece of Pressure treated wood from the top of that double up beam that was sized to fit between the two 2X's
    Then would have flashed the top of that beam with one piece of coil stock in the shape of a U up side down installed over Storm and Ice Shield to isolate it from the pressure treated wood. The U shaped piece would also have had two "tales" on the bottom to help devert the water to the drain system.

    Caulking was just a very bad idea and will never work.

    Also I have not used nails in any deck boards for at least 5 years, why use them instead of screws when nails are just going to come loose once the wood drys out. I even bought screw guns that I can use standing up.
    With the newer ACQ wood I've seen to many cases where the so called ACQ nails still rust at the heads, so I use Ceramic coated screws.
     
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  18. Aug 14, 2012 #18

    nealtw

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    Good luck!
     
  19. Aug 14, 2012 #19

    nealtw

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    Joe: That's where I would have gone too, but they claim to be able to do this with your old deck!
     
  20. Aug 14, 2012 #20

    joecaption

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    And it can be installed under just about any deck already built.
    But in this case it looks like it was not built according to the maufactures instrutions.
    It can not simply be nailed up under the old floor joist. It would have no slope that way.
    Picture how a droped ceiling is install, it's kind of sort of done the same way.
     

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