When installing your DekTek Tile deck, the sister joist is required on our standard installations. Of course, this does not apply to other applications like ground pavers or concrete slabs but on all elevated standard deck installations. The reason the sister joist is required is because it allows more space for the tiles to set on. If the sister joist wasn’t present, and the deck wasn’t framed to precision, there could be a failure down the road if something shifted. For this reason, the sister joists are required. (We also have our alternative elevated deck install in which the sister joist does not apply.)
