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philim01_gw

please help me with nail problem with garapa deck!

philim01
14 years ago

We have a decking company building a garapa deck for us. They've been working on it on/off for a month and we have had various problems with them. I am now noticing that where many of the nails are in the garapa floor boards, there is a bluish-black discoloration of the deck boards. The owner said that this is because the boards have not been sealed yet and that this will come off when I get it washed prior to sealing. My question is, why is it doing this to begin with? Don't a lot of people not seal their garapa decks? We are planning on sealing ours, but does everyone who doesn't seal get this discoloration? Or does it have to do with the kind of nail used.....is it corroding? I tried to search to find out if there is a certain kind of nail that is supposed to be used. A man at Home Depot said something about ACQ nails being code. I am very ignorant about construction, etc and just want to know what I am talking about when I talk to the decking company about this again. Thanks you in advance for any information....

Comments (16)

  • weedyacres
    14 years ago

    Sounds like they're not using the right nails. To avoid corrosion in your ACQ (pressure treated) framing, you need to use hot-dipped galvanized nails specifially approved for ACQ wood or else stainless steel. The garapa doesn't need this, but the nails are going through the garapa into the ACQ, so you do. Can you find the box of nails they're using and take a photo? While you're at it, take a photo of the discoloration and post it as well.

    The pros can better speak as to whether HDG nails have a negative reaction with garapa.

    BTW, typical (and better) installation of the decking is with screws, preferably stainless steel. They'll hold it better than nails.

  • philim01
    Original Author
    14 years ago

    Weedyacres, this just shows how ignorant I am. Turns out these ARE screws, although not stainless steel. I just asked one of the guys working on the deck. There are no more screw boxes around. Here are some pics:

    http://www.flickr.com/photos/41144499@N08/sets/72157622315851553/

  • philim01
    Original Author
    14 years ago

    Also, just want to add that what the deck building company owner told me is that there this always happens and the only way to fix it is to sand the garapa when they are done prior to sealing. He may very well be right but based on my history with them I just to verify that this is correct and that is not because of the kind of screws they used. I also want to make sure that once I do seal the garapa, this isn't going to continue to cause problems for us.

  • philim01
    Original Author
    14 years ago

    Ok. One of the wokers just came and told me that he was wrong-the screws ARE stainless steel. He even showed me the box. So, I guess the stains are just inevitable and something to treat?

  • weedyacres
    14 years ago

    I'm going to have to defer to the pros on this. I didn't have anything like that with my SS screws in my garapa. Here's one of your pics so they don't have to copy/paste your link above:

  • john_hyatt
    14 years ago

    Glav reaction to Garapa. SS will never do that. It looks like some of the screws lost the glav coating during install. Thats pretty common none of the glav screws now a days use the hot dip process. Just have the dude back one out and put a magnet to it if it sticks its not SS.

    Always use SS fasteners with S American lumber. J.

  • mike_kaiser_gw
    14 years ago

    That doesn't look like a stainless steel screw to me. My guess is that they started with galvanized screws and when you said something, they switched to stainless hoping to mitigate the problem. As John suggested, back one out and see if a magnet sticks.

  • deckman22
    14 years ago

    Looks like a Headcoat screw to me, they are SS w/powdercoated head.

  • mike_kaiser_gw
    14 years ago

    Maybe it's just my monitor or the stains but it looks like a Philips screw to me. Are Headcoat screws available with a Philips head?

  • deckman22
    14 years ago

    If that's a philips head then not a headcoat, they come w/square drive heads. I'll second what Steve said about the no gap.

  • L T
    8 years ago

    Lower grades of stainless steel can still react with Garapa. Best to use SS 316 grade. I have no black marks around my Garapa deck fixings and I used SS 316. I know of a Garapa deck which was installed using 304 stainless steel and there are black marks present. If you want to get rid of the black marks/stains you will need to replace the screws.

  • millworkman
    8 years ago

    Since you dug up a 6 year old post, how does replacing the screws get rid of the black marks/stains, Lloyd?

  • debi353
    8 years ago

    With Garapa Decking, you do not want to nail it, you need to pre-drill and screw it down. You want to use a 3166SS Screw, the 305SS will also react with your Garapa. You can use a deck cleaner and brightener made by Deck Wise. It is very inexpensive and easy to do. This will remove the marks and then you can apply your U.V. Finisher.

    Debi

  • L T
    6 years ago

    Sorry for the late reply millworkman but as debi353 says above replace the screws to SS316 and then clean with Oxalic acid to remove black metal reaction marks. This reaction occurs on many timbers including Cedar, Saligna and Kwila. This also occurs during construction when a grinder or drill is used with metal and the filings lay loose on the timber. As soon as the timber gets wet the black reaction will occur.

  • Katie
    5 years ago

    i see this is an old post but hoping someone can help. We just laid garapa on our deck outside. Everything that touches it turns black. We haven’t had a chance to seal it yet because construction isn’t finished. Planning to seal ASAP. Some of the marks are from the roof granules that blew onto the porch and then it rained. A few are from mortar. The mason tried to wipe clean and now it has a yellow ti

    znt. Any advice to remove any spots would be greatly appreciated.


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