There is nothing worse than walking out onto your deck barefoot and stepping on a raised nail. There are many reasons why nails lift, such as the age of the deck, an incorrect nailing pattern, or even over cleaning of the deck; however the root cause of the problem starts right back at the construction stage of the deck. It can start with something as simple as using an incorrect nailing pattern (bear in mind this is not the only cause, just the most common).
As you can see from the photo the nails have all been nailed in a straight line and this has sealed the fate of the deck. When decking boards are nailed in a straight line the nails act like a series of tiny wedges splitting the floor joist along its length. Over time this splitting of the floor joist is amplified by continuously wetting the deck, either by over cleaning (hosing) or weathering due to age. As the splitting gets deeper the nails are no longer held down by the floor joist and they eventually come free, rising up. When the nails start to lift it is time to make a very serious check all over the deck, including in between the decking boards, to see if the floor joists have started to split.
Best practise to avoid this problem is to stagger the nails rather than nail them in a straight line. This process is outlined in our “Installing Decking Boards” guide.
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