Drill holes to drain pooling water on decking?

Discussion in 'Landscaping and Outdoors' started by Kaboo, Jun 22, 2022 at 11:54 AM.

  1. Kaboo

    Kaboo Member

    Hi everyone,
    This is about a wood deck in our new home. Moved here last year and the deck was in a very poor condition after the winter, it definitely got ignored by us over the winter amid the chaos of moving, but quite sure that previous owners also had not been looking after it very well. Its like 4-5 years old, so there was not much/any damage, it was just coated with dirt and slippery with algae/mildew in lots of places.

    A month back I cleaned thoroughly and oiled and it looks much improved, no more slippery and I could see the wood. It has been re-oiled. But I have noticed that water pools in the middle on many of the boards. May be it was not installed correctly or it has bowed in the middle following the contour of the garden? In summers pooled water dries quite fast but in winters its there for a long time.

    Can I drill few holes, 1-2 in each groove where water collects? I will treat the hole with the decking oil I used on the surface, can do 4-5 coats. Think that should prevent the rot to start from the holes. But I am concerned that it might affect the strength of the board? Attaching a picture of the problem.

    PXL_20220618_164546267.jpg
     
  2. FlyByNight

    FlyByNight Screwfix Select

    The wet patches appear to be in a line, roughly, which suggests it may have sagged at that point, or was badly installed.

    To get the water to drain you will really need 6-8mm holes - anything smaller will not work. Try drilling a 2mm hole in a piece of wood and pout water on there - will it drip through? Probably not.

    SO, putting 2 x 8mm holes in each groove will turn it into a colander! It will drain, but the boards will be weakened and perhaps to a point where they become unsafe.


    I can see where the supports are underneath, so think about this:

    Remove teh screws from the boards in te two supports where water collects. Rout a 10mm wide groove, just a fraction deeper that the groves, maybe with a round cutter, perpendicular to the boards and across all of them. You will end up with two parallel tram lines but water should then drain. Refit the screws - proably in the new groove. The boards will be a little weaker, however there will be support immediately underneath.


    Others may have an alternative solution.
     
    Kaboo likes this.
  3. Truckcab79

    Truckcab79 Screwfix Select

    Looks like a nice install. Gaps are a little large in proportion to size of board but very nice. Bearers look correctly spaced as far as I can see from the angle in the that picture so I doubt they are bowing.

    Timber is never arrow-straight so I wouldn’t worry about it. Drilling holes will likely just make them rot more quickly. Just oil it and keep oiling it. Looks like it will be fine for years.
     
    Kaboo likes this.
  4. Abbadon2001

    Abbadon2001 Active Member

    Was it installed with fall in the boards? From recall any deck with over 4m lengths its recommended not to use groove up, as even with fall you cant rely on successful draining. Flat side up, the water can shed much more easily in multiple directions.
     
    Kaboo and MRY like this.
  5. MRY

    MRY Screwfix Select

    Unscrew the lot, one by one, and re-lay the boards the proper way up.
     
    Abbadon2001 likes this.
  6. Abbadon2001

    Abbadon2001 Active Member

    This, as with my reply, it wont pool if the grooves are not upward!
     
  7. Kaboo

    Kaboo Member

    Why would holes make it rot more quickly? I can oil the holes too!
     
  8. Kaboo

    Kaboo Member

    None of the boards are longer than 4m. I do not know how it was installed or if it was installed correctly with enough slope to drain at one end. These were installed by previous owners some 5 years ago and we bought the house last year.
     
  9. Kaboo

    Kaboo Member

    The ends of the boars are not free they are anchored under more timber that form part of raised flower bed. But may be from one of the ends I could lift them and shim them up?
     
  10. Kaboo

    Kaboo Member

    If it is not bowing then why water does not drain from one of the ends? I have poured water from either ends and it drains from the middle of the decking and last bit of it pools.
     
  11. MRY

    MRY Screwfix Select

    I don't understand. Another pic?
     
  12. Truckcab79

    Truckcab79 Screwfix Select

    Likely one of the bearers was bowed when it was installed, or has bowed after install. Or it’s sunk or isn’t supported properly or any one of a number of other reasons.

    with regard to your other comment. The holes are likely to increase the chance of rot as they will collect water and dirt and prevent the timber drying fully. You can oil them as you say but you would be better just oiling the whole undrilled board

    Holes in boards will also look awful if you drill enough and if they are large enough to be effective.

    Oil it well and often and leave it alone would be my advice. If you really want to sort it then take it up. Replace or shim bearer and re-lay but the orientation of the boards means you’re taking up most of your deck to sort it.
     
  13. Kaboo

    Kaboo Member

    I cannot take more work on my hands at the moment because have been redecorating non stop since moving in last year. With a demanding job and raising a child it has been very hectic. There is some more work still remaining and importantly I have only one month to complete it before the imminent arrival of my second child. If I create more work my pregnant wife swears she is going to kill me (and I believe her)!!

    So frequent oiling it will be for now. This time I cleaned it with Ronseal Decking cleaner and reviver https://www.ronseal.com/products/decking-cleaner-and-reviver/ followed by jet-washing. It took two runs of cleaning because it was in quite a dirty state. Then quick sanding if jet wash raised any grain in the wood. Then oiled, two coats with Ronseal Ultimate Decking oil, https://www.ronseal.com/products/ultimate-protection-decking-oil/. The question then how often should I re-oil it? Once every year? And will I need to wash/clean it the same way every time or just a quick jet wash?
     
  14. Abbadon2001

    Abbadon2001 Active Member

    you could always get a cordless leaf blower and go blow the excess off whenever its not raining, to minimise submersion time. Or for the winter, use a large tarp, and a few big beach balls to support the middle, and cover it over (making sure its dry before covering it up - leave a few gaps for through ventilation too during the winter also).
     
  15. Denis6482

    Denis6482 New Member

    I wonder if the OP could drill modest sized holes, maybe 4 or 5mm where the pooling occurs and treat with oil. Then when pooling is likely a few drops of washing up liquid will help the water run through the holes.
     
  16. Truckcab79

    Truckcab79 Screwfix Select


    Waste of time to be honest. They’ll block and just trap moisture and increase rot.
    Leave it alone. Oil it as regularly as you can be bothered. Once in Spring and once in Autumn will be plenty. Most people do nothing with their decks and they still last 10-15 years.
     
  17. Denis6482

    Denis6482 New Member

    Was there a suggestion that the boards in the OP are upside down or did I misunderstand?
     
  18. MRY

    MRY Screwfix Select

    If they're the proper way up, they're nicer to walk on, don't accumulate dirt and grip, shed water much better, look nicer, absorb less water, are easier to clean, and dry out faster. Unfortunately the OP has some sort of raised flower bed holding them down, it seems, the whole lot was installed by the person before, so they can't be turned over..
     
  19. Denis6482

    Denis6482 New Member

    Oh, I'm surprised! I thought most decking looked as the OP picture. So, the two sided decking boards have a fine grooved surface for the top and a coarse grooved surface for the top to let the water drip off, am I correct?
     
  20. Truckcab79

    Truckcab79 Screwfix Select

    Most boards are double-sided. The ridges go facing down. Manufacturers will tell you that the ridges aid airflow and stop it rotting. In reality any effect is marginal at best and there are far better ways of protecting them from rot. The grooves go uppermost and should be laid with a slight fall to allow the grooves to drain. This also assumes that the deck is laid properly supported etc. A properly looked after deck will last for many many years. Properly looked after means not letting the grooves fill with ****. Decking also isn’t slippery unless you don’t bother cleaning and treating it.

    I build and rebuild a lot of decks. Build quality on most is beyond shocking. Of course by the time anyone realises that the original builder is paid and long gone. I’m finishing off a rebuild currently as it happens. Includes 4 steps nearly three metres wide each. Each step only supported by one landscape screw suspending it from the step above. To be fair it’s lasted ten years so maybe I’m the idiot for over-engineering mine.
     

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