Using 6x2 C24 treated timbers as decking boards - any downsides?

Discussion in 'Carpenters' Talk' started by tygar2, Jul 9, 2020.

  1. tygar2

    tygar2 New Member

    Hi everyone. After some advice as I am a complete amateur and know very little.

    I rebuilt my deck frame using c24 6x2 pressure treated timbers and after months of searching and waiting, my delivery of 5.4m Canterbury style decking arrived today. Hard to find during lockdown as the local timber yards were either sold out, did grooves both sides only, or were not doing longer than 4.8m lengths.

    Anyway, I want smooth side up as I find grooves uncomfortable underfoot. From limited research, I believe grooves were actually designed to be on the underside anyway! What happened was the delivery driver noted the missus checking that the deck boards were smooth on one side and told her we would have been better off ordering 6x2s! That got me thinking - is there a downside to this? Are decking board just a 6x2 timber cut in half and grooved?:confused: Apart from thickness, to me, they look the same when looking down as the width is the same and the finish looks identical.

    At 2 inches, the timber will be much thicker than a deck board so should last longer and give room to be sanded down multiple times and take longer to rot through. The price difference is £1 (£12 for deck board and £13 for 6x2 - same length) which makes cost a non-issue and makes decking look like a bit of a rip off!:eek:

    Am I missing something very obvious or there major downsides? Only things I can think of are I might have to sand off some "C24" printing and waterproof the areas where the frame and underside of the top timber meet to make up for the lack of grooves for water to escape. I don't know...are 6x2s more likely to end up warping?

    I assume the slip hazard is no worse and the plan was to add an anti slip coating after oiling.

    Thoughts?
     
  2. Severntrent

    Severntrent Screwfix Select

    double the weight, larger/more support joists/posts required?
     
  3. rogerk101

    rogerk101 Screwfix Select

    That is indeed a factor, but only a relatively small one.
    When I lived in the USA, I was required to state the maximum number of people that would be on the deck during, say, a party and that was the number for which the deck's design was approved. If I exceeded the number of people on the deck and there was an accident, my insurance would be invalidated.
    It was quite remarkable how insignificant the weight of decking material becomes when compared with the weight of lots of people!
     
  4. tygar2

    tygar2 New Member

    My frame is made out of 6x2s as well. These are bolted into 4inch posts. Would this frame be inadequate?
     
  5. rogerk101

    rogerk101 Screwfix Select

    You'd have to provide a whole lot more information if you want to get any sensible opinions on that question. For starters ...
    What is the overall size? What are the joist spacings? What are the joist spans? What are the fixings? How many fixings per joint? What is the 4inch post sitting on/in? etc.
     
  6. tygar2

    tygar2 New Member

     
  7. Severntrent

    Severntrent Screwfix Select

    So 5 posts at 1.3 spacing on the 5.2m joists
    Structurally 3 x as strong as it needs to be to take 2 people/m2 (standard domestic floor loading)
     
    rogerk101 likes this.
  8. tygar2

    tygar2 New Member

    Thanks, that's good to know. I guess that means weight wise the 6x2s are fine. That leaves the orginal questional - Is it worth sending the decking back and getting 6x2s instead?
     
  9. rogerk101

    rogerk101 Screwfix Select

    No, not unless you've nothing better to do with your time. :rolleyes:
     

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