I''ll second the use of polyester rather than
epoxy....but for an entirely different reason:
Epoxy when layed up **thick** (such as what you are doing in deck repair) will most probably "go exothermic".... inotherwords will KICK catastrophically, generate a LOT of heat and possibly cause the unreacted
epoxy to foam and ooze out of the structure. The possibilities are: explosion (very very slow) of the deck, severe burns of the person who is doing the lay-up,
epoxy ''foam-out'', etc. etc. etc. etc.
With Polyester, you can do a single sandwich lamination (almost the whole thing at one time).
If strength is required, then
epoxy should be considered but layed-up in SINGLE LAYERS ---- to prevent excessive heat build up.
Hope this helps