Decking expansion gaps

Discussion in 'Carpenters' Talk' started by masonst0rm, Aug 3, 2006.

  1. wiggy

    wiggy Screwfix Select

    Just for you handy.

    Once upon a time (probably about 40 years ago) when decking first started becoming popular to our lovely country, all the potential suppliers where given samples and they all sat around in there office, probably in london and some chief executive officer who was a probably a woman said " hey i like this groove (kerf) and they all decided to market this new product with the groove (kerf) facing up, its as simple as that.
    Whatever way you prefer to lay it, its obvious that the general opinion is for smooth face up for all the reasons that have been given.

    Decks are laid level.

    Take a level bit of smooth decking and pour a glass of water on it, where does the water go? Off the edges?

    Take a bit of grooved decking and do the same. Where does the water go, down the groove?

    Which bit of timber holds more water?

    Now I really love and am often amused by your sticky back plastic and fairy liquid bottle ideas, but give this one up....
  2. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Wiggy, look. If you take a glass of water to level decking, if there is only a slight cup, the water will not run off the sides(unless slightly cupped up at the centre-which would be very unusual). If it's dead flat, the water will spread. Most of the width and some length of the board will be wet.

    If you pour a glass of water onto grooved decking board, the water will fill the grooves, the raised parts will be practically dry. This is the bit you walk on.
    Happy days. Slight slope and you won't be worried about any water.

    Now for someone else who has never heard of the FACT that less surface area means more pressure - go back to school.

    Otherwise we would all be driving around on legal bald tyres.

    FACT. 4 facts there for you.

    Mr. HandyAndy - Really
  3. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Chippie, I took some of my own boards up to bait a rat or two. As I took them up, I turned them over.
    They were cupped originally, they flattened before I put them back down.
    Simple top drying phenomenon. Top shrinks, edges cup upwards!

    And it proves also that it matters not if it is grooved or flat, the top drying causes the edges to cup upwards.

    Plenty of facts here, and personal witnessing.

    Mr. HandyAndy - Really
  4. wiggy

    wiggy Screwfix Select

    I bet you're a bundle of laughs down the boozer
    Joe95 likes this.
  5. seen it all before

    seen it all before Active Member

    Personally I just let the customer decide which way they want it fitting, and if fitted correctly and securely you should not get to many problems either way.
    wiggy likes this.
  6. mr moose

    mr moose Screwfix Select

    One thing to put in the mix ( it may have been said already but I cant read that many pages its too painful! :D) and that is most grooved boards have kerf cuts on the underside to stop cupping? So you cant turn them groove side down anyway (unless you want ugly curf cuts showing) Personally I prefered them without but I cant seem to buy them anywhere nowadays.
  7. parahandy

    parahandy Screwfix Select

    Cupping is determined by which way the grain rings are facing.

  8. chippie244

    chippie244 Super Member

    I can't see 4 facts there, all I can see is a man who cannot admit being wrong clutching at straw
    If less surface area means more grip do racing cars and dragsters run on bicycle tyres or dirty great slicks.
    Your post about water reminds me of the time you recommended floating a feather in a bowl of water as a crude spirit level, that again was you refusing to admit you were wrong despite all the evidence and pulling non facts out of the ether.
  9. chippie244

    chippie244 Super Member

    I've told him this but Handy knows better.
  10. dwlondon

    dwlondon Active Member

    I thought the feather in a bowl of water was originated from charliefarley back in the day......

    he disappeared with the indians somewhere in america.....
  11. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    No chippie. I have already said that a board will cup when drying(cup up at edges top drying), and by turning the board over, it will flatten out again.
    I have not only said it, but seen it with my own eyes, and could no doubt replicate it.

    And why do you think skis are smooth, twit? If they had cross ridges on the bottom, they wouldn't slide!

    Car tyres are grooved(treaded) to allow water into the grooves and out again, giving more grip.

    Racing cars have little tread and soft tyre when it is dry, and large grooves/treads when it is wet.

    Explain those 'FACTS' away.

    Mr. HandyAndy - Really
  12. chippie244

    chippie244 Super Member

    Handy, I'm going to let you have a good think about the rubbish you have been posting on here and how much of a fool you have made of yourself.
    It's pointless arguing with you because like Wry you are not one to let the truth have any bearing on the matter in hand and would prefer to spout contradictory rubbish rather than admit you might have got hold of the wrong end of the stick.
    What you have against you is the evidence from numerous websites and the experience of many carpenters who have specialised in decking against your observations of a board you once turned over, BTW which way were the rings running on this board?
    I don't really care which way anybody lays their decking boards and with correctly treated timber it shouldn't make much difference to the life of the decking as it should last 25 years anyway.
    This discussion evolved because it was stated that the grooves acted as a gutter to let the water flow away better, which is patently untrue, and then you have brought out made up "Fact" after made up "Fact" to try and prove your point.
    I'm sure you are going to come up with something ridiculous after this post as in the words of Vic and Bob "You wouldn't let it lie!" but frankly I'm over it. :):)
  13. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Just what is made up about why tyres have grooves, skis are flat etc.

    And why do boots have treaded soles?

    Flat-bottomed shoes+flat wet decking=slip. Guaranteed.


    Grip is provided by treading/grooving.

    It's fkin obvious.

    Take a search for some decking on google. Ratio of groove up pictures to flat pictures please?

    See for yourself. Like I see for myself when boards flatten out when turned, REGARDLESS of how they are cut.

    When drying they cup up at the edges REGARDLESS of grooves or how they are cut.

    I have see it happen on more than a few occasions.

    I will not argue with what I see for my own eyes!

    So go on. Explain the tyres away. Explain grip without tread.

    Explain how a drying area of timber can expand, when YOU KNOW it must shrink.

    How detailed do I have to explain it to get it through your thick head.

    The top dries. It shrinks. The bottom is wetter. It expands. When the top shrinks and the bottom expands, it MUST cup up at the edges. MUST. Turn it over, same effect straightens the cup.

    It's not rocket science and if you don't get it, I pity you.

    Explain, you can't. You are wrong. It happens.

    Mr. HandyAndy - Really
  14. Rulland

    Rulland Screwfix Select

    Anyone fancy a pint?, preferably together :p
    seen it all before likes this.
  15. The tyres are heated up and stick to the track.
  16. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    I know that. Slicks have no tread and are soft and heated and stay heated.

    They don't stay that way when wet.

    Treads allow water into the grooves and away, allowing the smaller surface area to provide grip in the wet.

    Mr. HandyAndy - Really
  17. Why did you ask the question then?
  18. seen it all before

    seen it all before Active Member

    Yes please, mines a smooth something to grip my thirst!!!
    Rulland likes this.
  19. Mr. Handyandy

    Mr. Handyandy Screwfix Select

    Because chippie seems to doubt that grip is achieved like that, and I would like to see him explain it in any other way, other than factually as I have.

    Mr. HandyAndy - Really
  20. chippie244

    chippie244 Super Member

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