How do I attach cover locks to an in ground spa? Mel June 21, 2018 04:15 Updated Follow The lock portions are installed with screws, flat on the surface that the spa in in. We suggest that you use screws suitable for the surface that you are drilling into. See below for examples in Brick and wooden decking. Related articles My spa is in my deck, can I still use a cover? Comments 0 comments Article is closed for comments.