How to measure the angle of a patio?

[puntloos]

1 hour ago, saveasteading said:

yes.

but NB a french drain will always allow some water to seep downwards. But it will not harm the foundation. It is there to pick up large quantities and take it away.

Everyday drizzle will not be taken away, and so the wall may be damp.

Interestingly though, I don't think I've ever seen my french drain be wet at all, even during downpours. This suggests that the direction of the patio fall wouldn't influence this either way 

1 hour ago, saveasteading said:

sloping away is usually better if you have the choice, for that reason and to avoid weeding and annual cleaning of the surface gravel.

Well, I somewhat have the choice, currently the patio is basically flat (to my best guess maybe 1:200 angle away from the house..) so assuming we do something at all, I might get a choice.. but for now an additional issue for me is that the turf and underlying clay right next to the patio really don't want to absorb any water, not to mention I want water to be sent to my harvester tank..

[saveasteading]

58 minutes ago, puntloos said:

maybe 1:200 angle away from the house

that is flat really. 

 

59 minutes ago, puntloos said:

I've ever seen my french drain be wet at all, even during downpours.

 

That is because you haven't dug it up during or just after a downpour. e water is going somewhere.

The volume of the gaps between stones, plus the empty pipe is probably swallowing up all the water, so you would have to delve down to find water.

It first runs through the gravel. If it gets deep enough it enters the pipe and some may run away. The rest will percolate downwards.

 

[Thorfun]

On 03/08/2024 at 15:39, puntloos said:

If the house has a full french drain around its perimeter (that goes to rainwater harvester),

I didn’t think a French drain in to a rainwater harvester was a good idea. Too easy for contaminants from the patio to end up in there. 

[puntloos]

53 minutes ago, Thorfun said:

I didn’t think a French drain in to a rainwater harvester was a good idea. Too easy for contaminants from the patio to end up in there. 

Yes, this is indeed a concern for me, I'm pretty sure the aco drain (I keep saying french drain, not sure of the difference) goes to the rainwater harvester. Should certainly be careful with 'cleaning liquids'.

Edited August 4 by puntloos

[saveasteading]

50 minutes ago, Thorfun said:

Too easy for contaminants from the patio to end up in there. 

good point. but if the water is only for gardening it will be ok. But not for domestic use.

It is in your control, to not use nasty chemicals.

Is there an overflow and where does that go?

[puntloos]

3 minutes ago, saveasteading said:

good point. but if the water is only for gardening it will be ok. But not for domestic use.

It is in your control, to not use nasty chemicals.

Is there an overflow and where does that go?

Borehole soakaway

[Mr Punter]

The lawn looks too high and is acting as a dam which is why the patio is not draining.

[saveasteading]

another way is to form a V with the paving, and a channel along the low point, whether a drain or slab, then picked up at the ed.

best avoid using the name Aco unless you really want that brand. it is good stuff and priced accordingly. there are economy plastic versions which are fine when not driven on.

I withdraw that: Aco seem to have one at £12/m

do you need all these RWPs?

Have you a spec and price for the borehole? that could be costly.

[puntloos]

2 hours ago, Mr Punter said:

The lawn looks too high and is acting as a dam which is why the patio is not draining.

 

Well, this would be true if we weren't trying to catch the water in the aco drain?

[Mr Punter]

13 hours ago, puntloos said:

Well, this would be true if we weren't trying to catch the water in the aco drain?

 

There will be very little water in the aco as the paving slopes away from it towards the lawn.  I think it is getting trapped by the high turf level and the scaff planks.

[puntloos]

On 05/08/2024 at 09:08, Mr Punter said:

 

There will be very little water in the aco as the paving slopes away from it towards the lawn.  I think it is getting trapped by the high turf level and the scaff planks.

I think you're missing the point that indeed the current paving is effectively flat but was certainly intended to be sloped. Instead, IMO, the paving should have sloped towards the ACO. Or would you disagree?

[Mr Punter]

Ok I understand.  I normally like to have paving sloped away from the building.

[puntloos]

32 minutes ago, Mr Punter said:

Ok I understand.  I normally like to have paving sloped away from the building.

Even when ACO drains are present? I somewhat see the point but I have a full rainwater harvesting system (big tank underground etc) so presumably catching all the water I can seems reasonable.

[puntloos]

Small followup, while my measurements turned out to be.. uh.. not great (with all the tricks in this discussion I arrived at about 0.5%) - but I bought myself a calibrated level, pretty cheap too from vevor. Reality: - 0.2% (the level is more accurate in degrees mode, this particular tile is 0.10 degree which is about 0.18 %

 

I think it's safe to say this patio is flat. 

 

But if I get my builder to re-do the patio (they will be very excited about this).. should I still push for angled towards my french drain, or angled away from the house? I think french drain is probably still the better idea, it catches the water (for my underground rainwater tank) not to mention that the grass is on clay, and not great at absorbing water. Or?