When installing composite decking it is recommended to read up on the literature that might be available on the manufacturers website or if it comes with the tiling. When considering composite decking which are made of plastic and wood fibers it is important to consider thermal expansion as most climates have temperatures that fluctuate around a lot which would create an issue with how the decking would be spaced in summers and winters. Proper spacing will allow some movement without buckling as composite deck tiles tend to shrink or grow across their length in summers and winters.
There are existing composite decking design functions that allow it to be installed with hidden fasteners. These systems are first screwed directly in the deck frame across each joist and are meant to fit perfectly and tightly in the cavity that will be present in the sides of the boards.
Mushrooming is a common problem that occurs when a bugle head screw can pull some of the composite material above its surface during the installation phase. It ruins the overall look of the deck as the resulting bump sticks out like a sore thumb. This can be fixed by using a hammer to level the surface but it may damage the composite decking if done incorrectly. It is suggested that thread screws are used when composite decking is face screwed as it would eliminate mushrooming thus hammers would not need to be involved.
Controlling Deck Seams
The Control of the deck seams is dependent on the size and shape of your deck.
It is recommended to avoid seams across the surface of your deck. Butt joists will tend to create some separation but these will warp as the decking material eventually weathers out.
This really depends on the size of your deck. Depending on the shape and size of it you might need to make some minor adjustments and be done with it at no cost or maybe even major adjustments sometimes as it would dictate the number of butt joists that would need to be used.
One way to counter this is by using a division board as it not only would help you create a continuous seam but such an arrangement would also give it the look as if the seam is a part of the design. This would make the deck look much neater but also pleasing as it adds a lot to the aesthetics of the deck itself. By using the technique you can control the seam and make it look as if the design dictates for there to be a seam.
Another way we can control the seams is by proper planning and arrangement of the deck tiles. If the deck is wider than 20’ then the decking can be applied diagonally which would not only eliminate the seams but also give it a different look visually. This would also reduce and at some times entirely eliminate the need of butt joists which warp and degrade as the decking material would weather.
For example on a 24' wide deck, with some extra space that allows for some room to work around, the butt joints can be staggered to around every 4’ eliminating the over reliance of butt joists. Alternatively, you can use a division board to create separate decking fields to hoist the decking on. This would not only control the seams but would also be the easier method of solving the deck seam issue.
It is important that whatever composite butt joints are used it is level both the joists to the same height. For every 12”, using 4 screws , preferably thread screws are recommended as it would make sure that the butt joints are fastened properly as these are essential deck support structures keeping your decking in place.
Read more: How to Properly Space Deck Boards
It is important to level the joists as this would keep the butt joints at the same height. Using 2 clips on a double joist is important when using a hidden fastening system. Each butt joint should have ⅛” of a gap at least so that it allows space for decking to expand or contract when dealing with climates that have a very fluctuating temperature.
For a hidden fastening system, first you must screw the first board and then add a hidden fastener clip to the groove that has been created on the top of each joist and then slide the next board in the clips and use a rubber mallet to tighten it.
Don't hesitate on making minor adjustments to the decking boards as a properly spaced deck is not only clean but also makes sure they last longer without damaging the decking. The same should be done for rail posts that are inside your deck. Gaps that are left can be covered by using a rail sleeve and base trims.