Indian Sandstone Patio Fall

Discussion in 'Landscaping and Outdoors' started by Rb987, Sep 27, 2021.

  1. Rb987

    Rb987 New Member

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    Morning. I'm hoping to get some thoughts on my new patio. The guys laid this last week and for the most part it looks fine. It's on a full bed of mortar on a compacted subbase and an existing concrete slab. I wasn't around to see how well compacted it was so I can't comment on that. The size is roughly 4.2 by 3.5. The concern I have is that I meaure the fall at about 1:200 corner to corner. Obviously online the expected fall for indian stone is around 1:60. It does mention that this can be different depending on the project. My hope I guess is that as it's a small patio we might get away with this fall. No moneys changed hands yet but these are good guys I don't really want to have to go down that route. Any thoughts on how the fall and how likely we are to have significant problems?

    I've attached a still from a video I took of the area in the very heavy rain this morning (sorry about the quality). I went out there when it was a little less heavy and it didn't seem as bad as it looked from the house. Obviously it's going to look wet in heavy rain so the question is whether this is a sign that the fall will give us a problems, and whether there's anything we can do in terms of when we do the pointing that will help rather than hinder the drainage?

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    Last edited: Sep 27, 2021
  2. dray

    dray Active Member

    Is it draining corner to corner then?
     
  3. Rb987

    Rb987 New Member

    Hi. Thanks for your reply dray. Sorry I've now marked the fall as measured in two places on the image. I measured the fall with a lazor level after dark so I could see the line. The blue line falls 16mm over 4.3 m (1:268). The red line falls 25mm over 5m (1:200). I was as accurate as possible but obviously there's room for error in my measurements. Fall direction is from the rose on the left to the top of the image.

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    Last edited: Sep 27, 2021
  4. dray

    dray Active Member

    Looking at the coloured lines which direction is the fall going?
    Which way did you expect the patio to fall ? Was this discussed prior to build or did you leave it to them to sort out?
    Are you sure they have not put the main fall from the brick wall on the right across to the rose bush side ?
     
  5. Rb987

    Rb987 New Member

    Fall was discussed during the build but not ratios. I should have remembered to discuss ratios to make sure this was covered but we have a lot going on and I didn't raise it. I'm frustrated that I didn't tbh but it is what it is. My hope is to try and establish whether the fall is badly wrong given the size of the patio. In the image the fall is going from the rose bush to the top. I was told fall was toward the top of the image, so I've measured as such, diagonally it's a bit better (1:200) so that's something. We had heavy rain this morning. I went out during and after, it didn't seem horrendous, there are a few puddles remaining after maybe 2 hrs dry, put there's no pointing yet so obviously the water can easily move away.
     
  6. dray

    dray Active Member

    Fall is what you need to know, are you saying that the patio is falling from bottom (wheelbarrow end)to the top (directly opposite end)? Am I right in saying that the distance between the two points is 3.5 metres? A fall of 1.60 which you say you need, means that over that distance you need the top to be 58mm lower than the bottom. ie 3500mm divided by 60=58mm.
    I think you can tell from the brickwork that it is not falling that much so perhaps you need to talk to the builder and establish which way it is falling and whether it has the correct fall on it before paying them. Have a look at the paving expert .com site under calculators and it gives a wealth of information that will help you.
    Good luck and hope you get it sorted.
     
  7. Rb987

    Rb987 New Member

    Thanks Dray. It's not so much me saying I need 1:60 as that's what I see online for indian sandstone. It seems to be what the suppliers are saying is necessary, tbh given sandstone is permeable 1:60 seems quite steep I'm mainly wondering how much worrying I need to do and whether I could consider a pemeable grout in order to help avoid any future issues.
     
  8. dray

    dray Active Member

    Sorry RB, I didn't mean to offend and I agree that 1:60 or 1:80 (depending on who you follow) is what you should have on the patio fall.
    I am just struggling to understand where the fall actually is and whether you have got the right measurements from the right place. I do hope you have and it alleviates your fears but, at the very least you need to determine the minimum fall so you can discuss it with the builder. It may be that they will put a straightedge and spirit level on the patio and show you it is correct, but if not then get them to put it right to your satisfaction.
    Regarding the grout being permeable, I'm not sure that I would rely on that, but once you have accepted it then no going back really.
     
  9. WillyEckerslike

    WillyEckerslike Screwfix Select

    Anything between 1:60 to 1:80 should be alright for most patios unless the manufacturers specifically state otherwise - porcelain tiles usually have pretty detailed instructions for instance.
    Despite the notion that sandstone is permeable you should consider them impermeable for matters relating to drainage and pointing will seal the patio - permeable grout's not really a thing unless you've got a drainage system installed under the patio.
     
    dray likes this.
  10. Rb987

    Rb987 New Member

    No offence taken dray just trying to be clear. I can't really be sure that I have the right measurements from the right place till I have the guys here to show me. By my count we're at 1:200 which is a good bit off 1:60, that's why I'm a bit worried. So Willy, does that mean there's nothing to be done? If someone laid your patio at 1:200 and you hadn't paid them yet how would you approach it?
     
  11. Rb987

    Rb987 New Member

    I've attached an image of about a 2 hrs after the rain. A few damp patches but it's not a swimming pool. Again this is pre pointing so hard to know how it will be after pointing.
     

    Attached Files:

  12. Kas228

    Kas228 Screwfix Select

    More important in my book that you don’t have any hollows or dips where water can and will collect. You have a fall as long as it’s consistent over the whole length personally I think you will be ok
     
    WillyEckerslike likes this.
  13. Truckcab79

    Truckcab79 Active Member

    That’ll be fine. Correct fall is more of an issue where it’s sending water away from your property. This looks like it’s not going to do any harm whichever way it drains.

    Sandstone is heavily riven. You’ll always end up with a section on one or two slabs that is a bit lower and holds water for longer.

    They should have put more of a fall but I wouldn’t be too concerned.
     
  14. WillyEckerslike

    WillyEckerslike Screwfix Select

    You need to put the onus on them. Unless you specified otherwise you would expect a patio to drain of its own accord and that is what they should have provided. Tell them that if it holds water or has puddles once pointed (other than dished/hollow slabs) they will have to resolve the problem or possibly relay the patio. Pay them on results.

    The point @Kas228 makes is good and assuming that there is an even fall you can do things to help - ensure that water isn't trapped once it gets to the lower edge of the patio with some form of French drain for instance.
     
  15. CGN

    CGN Screwfix Select

    If it’s got a fall and is flat and nicely laid then don’t overthink it. Too much gradient on a small patio is painfully noticeable.
    You won’t be sitting out there in the rain.
     
    longboat likes this.
  16. Rb987

    Rb987 New Member

    That's very helpful guys - thanks for all the responses. There's another patio to go down so I'll make sure they show me the fall on the base before they lay it and once it's laid.
     
  17. CGN

    CGN Screwfix Select

    have you put patio furniture on it? A table?
     
  18. Kas228

    Kas228 Screwfix Select

    Even if the patio was completely flat (which it’s not as you have a slight fall) the water will find it’s way off. As I said earlier it’s dips and hollows you should be worried about as water will collect there if present
     
  19. Rb987

    Rb987 New Member

    CGN I've no furniture on either patio yet but expect to have a small table on the bottom one and a larger table on the one nearer the house. Expecting the one closer to the house to fall away from house and towards lawn at around the 1:60 ratio.
     
  20. CGN

    CGN Screwfix Select

    I helped lay a 100m patio with a relative a few years back for one of his regulars. It adjoined another patio which had been laid by someone else a year or so previous, as he wasn’t able to do this due to illness. The fall was way to much (although a neat job). It just looked wrong and any garden furniture was visually obviously on the scunt and awkward to use.
     

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