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Thread: Finishing a deck water & oil based

  1. #1
    Join Date
    Sep 2007
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    Atlanta, GA
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    Finishing a deck water & oil based

    Hello,

    It's been quite a while since I was here; my ww days are over due to health issues.

    If this question belongs elsewhere, please accept my apologies, and move it.

    My question is about finishing our enclosed deck. We have a deck w SPF flooring. When we recently did the enclosure, we had the floor professionally sanded, and we put this Behr stain on it:

    Behr.jpg

    It is an acrylic, and water is the solvent.

    We had some folks come by and spread it on the deck (they really slopped it on-parts of the deck were sticky for 2 weeks) that was about 2 months ago :

    Deck while drying.jpg

    We want to put Polyurethane (oil-based kind) over it when it is dry. It doesn't have to be oil based, just my preference for durability.

    So, I have learned on SMC: Let all the water evaporate prior to overcoating it w Polyurethane, and I'll have to put a coat of dewaxed shellac in between these two incompatible finishes.

    To further complicate things, I have a Delmhorst hand-held moisture meter that reads on some unstained decking about 12%.....Most of the stained wood is 14-15%. My wife pointed out that I only need to push the pins of the meter 1-2mm into the wood.

    My questions are:
    1) Do I need to wait until the stained deck boards read 12% (not 12.5%, etc), the same as my unstained controls-before I overcoat?

    2) Since this deck has been drying all summer (2 months), can any constituents in the Behr stain give me false moisture readings?

    3) If I must use oil-based polyurethane for protection, I have to put down a layer of dewaxed shellac.....what pound cut, how many coats please?

    4) I am tempted to KISS and use water-based polyurethane for protection.....if I do, will this make the entire "how dry is it?" question moot?

    5) Is water based polyurethane as durable as oil based?

    I did not know where else that has the know-how that you all have.

    Thanks so much for helping out.

    David
    David
    Confidence: That feeling you get before fully understanding a situation (Anonymous)

  2. #2
    Join Date
    Feb 2003
    Location
    Yorktown, VA
    Posts
    2,754
    David, I'm following with some curiosity. The Behr product is designed to provide protection for exterior decks and does not require an additional top coat. Will it not give you good service on your enclosed deck without trying to top coat with poly?

  3. #3
    Join Date
    Sep 2007
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    Atlanta, GA
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    I really don’t know
    We are on a mission though-so when we retire in a few years, as much as we can, we’ll be maintenance free

  4. #4
    Join Date
    Mar 2003
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    SE PA - Central Bucks County
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    Devid, honestly, if the deck surface is wood, there really isn't any kind of "maintenance free" option. Leaving it with just the stain will make any future refreshing much easier than if you top coat that with a film finish. The fact that you can only really finish the top due to the nature of the project also indicates staying away from a film finish...the stain will not seal the wood and it can breath on both sides with seasonal changes in temperatures and humidity.

    To have "maintenance free", you'd pretty much have to pull up the wood and replace with a non-wood composite and even that has some eventual lifetime, although it would unlikely be something that "you" would have to worry about give that's a long time.
    --

    The most expensive tool is the one you buy "cheaply" and often...

  5. #5
    Join Date
    Feb 2003
    Location
    Lafayette, IN
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    You say the deck is enclosed…is it completely weather-tight, and conditioned space? If it is not, forget any sort of polyurethane designed for floors—they’re designed for interior floors in conditioned spaces. They won’t last in wide temperature and humidity swings.
    Jason

    "Don't get stuck on stupid." --Lt. Gen. Russel Honore


  6. #6
    Join Date
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    I would be very concerned about applying a film finish on a deck, even if it is covered and enclosed. Since it is a deck, it is likely that it is open underneath so moisture will still be a problem. From the photo you provided it appears there are spaces between the flooring boards, so air and moisture can come in from below. Your locale has significant out side humidity so it is doubtful that the wood will ever get below 10-12%. I would stay with the current coating.
    Lee Schierer
    USNA '71
    Go Navy!

    My advice, comments and suggestions are free, but it costs money to run the site. If you found something of value here please give a little something back by becoming a contributor! Please Contribute

  7. #7
    Join Date
    Sep 2007
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    Atlanta, GA
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    I've known for weeks that I'd be asking this of you all, and glad I did.

    Everything you all have said makes sense; we have decided to leave it alone, and start using it.

    Thanks a bunch guys.

    Best, David
    David
    Confidence: That feeling you get before fully understanding a situation (Anonymous)

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