I am building a 20’x22’ attached Fiberglass pergola to my home. The ledger board is Fiberglas and a length of 19’. The pergola weighs approximately 700 lbs. The wind gusts can reach up to 50 mph, not including hurricane winds that can reach higher wind speeds. What lag screws (size and length) should I use if I am attaching the ledger board through vinyl siding and into plywood? Also, is there a certain pattern that should be followed (number of screws and distance apart)?

  • Does the ledger support 700 lbs. uniformly per foot over the entire 19 feet, or uniformly distributed over the 19 feet? (Which is about 37 lbs. per foot. ) Uplift (wind load) is a consideration but we need to know how big of a building the ledger is supporting. (Uplift is “wind pressure up” minus the weight of the material in the structure.)
    – Lee Sam
    Jan 27, 2020 at 3:35
  • 1
    When you say “fiberglass” do you mean PVC or polyurethane? I don’t think of fiberglass boards as “structural”. Usually they are trim, fascia, etc. Are the pergola supports sitting “on” the fiberglass ledger, or are they hung off the ledger with hangers?
    – Lee Sam
    Jan 27, 2020 at 3:42
  • I have never seen fiberglass used as a ledger, are there special fasteners?
    – Ed Beal
    Jan 27, 2020 at 4:47
  • The pergola manufacturer did not provide screws to attach the ledger board. That is the reason for my question. The pergola comes with a fiberglass ledger board. There are metal brackets that get screwed into the ledger board and the fiberglass beams get inserted around these metal brackets and get screwed in on the sides of the beam into the metal bracket. There are 2 sets of beams on the left and right side of the pergola that go out from the ledger board to a metal posts 20’ away. There are 11 rafters 19’ wide and 19 perlins 22’ long. The weight is distributed on top of the beams equally.
    – Joe Parisi
    Jan 27, 2020 at 21:34


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