What treatment for new Pergola?


I've just had a new pergola installed using pressure treated "Canadian Lumber Stock" or something like that - it's the wood that looks like joists but has rounded edges.  Anyway, I like its light colour so don't want to stain it but I do need to finish it with I'm thinking a clear preservative.  There are markings on the wood so I'll need to sand them off but in my searches for a suitable finish I've become confused - do I go oil-based or some other finish?  What have others tried and been happy with?  I did have new sleepers in my last garden that I loved as they aged and became grey but as I was leaving, they had started to crumble so I want to avoid this (having spent a fair bit on my new investment and it's raining now!).

Thank you for ideas,




  • Mark 499Mark 499 Posts: 380

    If the wood is recently pressure treated don't apply anything yet, give it about 6 months to weather then look for a coating that is listed as suitable for pressure treated timber, do not apply any oil based product if the pressure treatment has not weathered as it will not take.

  • CloggieCloggie Posts: 1,177

    ooh thanks Mark, I've read this elsewhere too.  Little worried though about the end grain that's on top of the posts and being recently sawn, exposed!  My profile pic shows the pergola and there are sawn joints between the supports and cross beams that will be letting in water.  We used bituminous paint on the ground side of the posts so they will be ok.

  • adoutR2adoutR2 Posts: 4

    Mark 499 is correct.  just let it cure until the fall.  If you paint wood outside, plan on repeating the process ofter through the years.  Do you know that you can "stain" it with many colors of solid stain, including "White" (white or off white makes for a striking Pergola)?  If you use a stain you will not have to re-coat, nearly as often.  I know.  I'm a retired painter. image

  • CloggieCloggie Posts: 1,177

    hi adout, got a strange feeling of deja vu - I'd already researched this topic and your answer is something that I've already read elsewhere.  Thank you for the help but I don't feel entirely satisfied that my original question has been answered.  I am looking for guidance from others who have made the decision to keep their outdoor wood a natural colour and have been happy with the finish and durability of the product they decided upon.

    Glad to hear from anyone who's recently had a pergola installed and have chosen a product to finish it in and are happy with the result.

    Thanks, TT

  • AWBAWB Posts: 397

    Teak oil, works for me.

  • CloggieCloggie Posts: 1,177

    Thanks AWB, I'll research Teak Oil.


  • Actually Tetley, you need an answer from someone who had a pergola installed 20 years ago!

  • Mark 499Mark 499 Posts: 380

    I wouldn't put any kind of oil based product on it until it's well weathered

  • CloggieCloggie Posts: 1,177

    Yeah, you're right Joe_tG but that would be good old fashioned creosote like my 14 yr old shed no doubt! image

  • CloggieCloggie Posts: 1,177

    I already have (in stock for another job) some of this stuff so I'll give it a go and then decide what to do long term  http://www.screwfix.com/p/sika-sikagard-universal-5-star-wood-treatment-clear-5ltr/66962

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