Angle of deck boards for best strength

Discussion in 'Decks & Patios' started by swimmer_spe, May 14, 2019.

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  1. May 14, 2019 #1

    swimmer_spe

    swimmer_spe

    swimmer_spe

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    I am planning on building a deck for my RV. It is not located anywhere that building codes apply.

    It will be 8 feet by length of trailer.

    I am considering using 2x4s for the structure and 1x6s for the top. Does it matter whether they are at 90 degrees or 45 degrees to the joists for the most strength?
     
  2. May 14, 2019 #2

    Snoonyb

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    The resilience will depend upon the joist spacing.

    1X placed perpendicular to the joist will allow each board to deflect when stepped on, diagonally they will not.

    1X floor seating, at a 45 degree, has been the standard for years.
     
  3. May 14, 2019 #3

    swimmer_spe

    swimmer_spe

    swimmer_spe

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    16 inches on centre joists. Sounds to me, 45 would be the best go.
     
  4. May 14, 2019 #4

    nealtw

    nealtw

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    At 45 degrees the distance between joists is greater so the joists should be at 12" OC

    You can find that in the instructions for composite decking.
     
  5. May 14, 2019 #5

    swimmer_spe

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    If I want to stick with 16'' on centre, 45 is not the way to go?
     
  6. May 14, 2019 #6

    nealtw

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    It's 20 inches between joists at 45. so I would leave it at 90 where you have 14 1/2 between joists.
     
  7. May 14, 2019 #7

    Snoonyb

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    20" is the long dimension, however, 14-1/2" is the short dimension, and it is after all, apples to oranges. IE. composite to actual wood, milled from a tree.
     
  8. May 14, 2019 #8

    swimmer_spe

    swimmer_spe

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    I am trying to do this "on the cheap" So, what lets me use the least amount of board feet?
     
  9. May 15, 2019 #9

    nealtw

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    45 degree would be the biggest waste with angles cut on both ends.

    Logic says at 90, 8 or 12 ft lengths will have the least waste but if you look at the distance to first and last joists from the ends, and some times 10s will give you less waste.
     
  10. May 15, 2019 #10

    Fireguy5674

    Fireguy5674

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    Also, if I read your OP correctly, you are planning to use 2x4's as framing? I would use at least 2x6's to support your decking material. It depends somewhat on your framing support system. But if you are planning to span the full 8' I would be looking at a minimum of 2x6 joists.
     
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  11. May 15, 2019 #11

    swimmer_spe

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    I am willing to have more deck blocks to support it, but I need the deck to be built as light as possible.
     
  12. May 16, 2019 #12

    Fireguy5674

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    I am not sure what you mean by deck blocks, but I am assuming (and we all know how that works) you will be running the deck joists at a 90 degree angle to the trailer. If they are 2x4's you will have a sizeable belly in your deck fairly quickly unless you support the middle some how. How high will your deck be above the ground? When you refer to deck blocks are you saying you are planning a support under the middle to cut the span?
     
  13. May 16, 2019 #13

    swimmer_spe

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    The joists will be roughly 4 feet long, running perpendicular to the trailer. The deck will be in 4x8 sections so if it needs to be moved, I can move it without fully dismantling it. The deck will only be a foot or so off the ground. Th deck blocks are the concrete blocks used to support decks. To make it structurally sound, putting them every 4 feet is fine. It will mean the deck is lighter when it comes time to lift it.
     
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