How to measure the angle of a patio?

[puntloos]

My current patio keeps standing water, even though there's a french drain next to it. 

Does this mean the tilers didn't put down an appropriate angle? A "random video" online tells me that for proper draining you need at least 2%, so 2cm per 100cm? Or is it not standard to angle outdoor tiles a little?

 

What's an accurate way to measure the drain angle of the patio? 

 

Or can I just from this picture claim the patio isn't angled appropriately?

(for what it's worth the scaffolding planks might've stopped some of the potential draining, although I imagine water would find a good way around it?)

 

 

[joe90]

Put a spirit level on it 🤷‍♂️yes minimum 2%.

[JohnMo]

5 minutes ago, joe90 said:

Put a spirit level on it

The buble should be biased towards the lines either left or right of centre. If it's in the middle it's flat not sloped.

[puntloos]

3 minutes ago, JohnMo said:

The buble should be biased towards the lines either left or right of centre. If it's in the middle it's flat not sloped.

 

Cheers, but the challenge is more to measure what the actual angle is. I think you can't tell from a spirit level if it's 1% or 3%? Or is there a way to semi-accurately eyeball this with a spirit level?

 

And so I take it indeed I should expect 2% slope else I can say they didn't do a good job?

[joe90]

If you want 2% use a 1 mtr piece of wood, stick a 2cm little block one end and put your sprit level on it on the patio (block lowest end) and the bubble should be central. This will give you an idea of the slope (or not).

[Ferdinand]

The surface of the water will be perfectly level, so you can judge the gradient of the patio it by measuring the depth of water in mm at each end.

If the measurements are too small to measure easily, add more water .... 😛😉.

(TBH I'd suggest that the water escape routes are perhaps blocked with all that dust'n'gunge.)

[puntloos]

50 minutes ago, joe90 said:

If you want 2% use a 1 mtr piece of wood, stick a 2cm little block one end and put your sprit level on it on the patio (block lowest end) and the bubble should be central. This will give you an idea of the slope (or not).

 

That's a great tip. Easy to do. Will figure it out.

39 minutes ago, Ferdinand said:

The surface of the water will be perfectly level, so you can judge the gradient of the patio it by measuring the depth of water in mm at each end.

If the measurements are too small to measure easily, add more water .... 😛😉.

(TBH I'd suggest that the water escape routes are perhaps blocked with all that dust'n'gunge.)

It's certainly better now, but agreed there's still some dust and grime but not really "mountains" of it. 

If anything the tiles are angled away from the drain:

[joe90]

Looks like a slight fall but not much. Water has a surface tension which is why a minimum of 2% is advocated. 

[saveasteading]

20 minutes ago, puntloos said:

That's a great tip. Easy to do.

Do it then reverse the spirit level. They are often inaccurate. If you get the same bubble position then you have confirmed the accuracy. If it is a different position then the average applies.

a 2p coin is about 2mm thick. 

 

[MortarThePoint]

I'm a fan of laser levels so you can do this with one too. The laser shines a level plain so, with the laser set up in single position, as you move away from the house you should measure and increasing height between patio and laser beam.

Edited June 23 by MortarThePoint

[puntloos]

2 hours ago, joe90 said:

Looks like a slight fall but not much. Water has a surface tension which is why a minimum of 2% is advocated. 

But to be clear - this is the wrong way.. the bubble is slightly 'toward' the drain, so the slight fall is towards the grass. (which is on pretty solid clay sadly so it soaks the grass)

[Nick Thomas]

My smartphone has a spirit level application (https://f-droid.org/packages/org.woheller69.level/) which is surprisingly great - although YMMV with the quality of the sensors in the hardware, of course. It's been very handy for measuring the actual angles of things that are already up, though.

 

Just make sure you use a flat side on the phone, not a side that has protruding buttons or cameras or whatever. Don't ask me why I need to say this.

 

 

[Dave Jones]

depends what you mean by standing water. porcelain hangs onto a couple mm all over, more if there is a dip/bow which nearly all porcelain has.

 

Use your level from the house pack it up on a couple bricks make it dead level then move over and level off last pile to next until you are at french drain. tape measure starting block and end block do the math.

[puntloos]

OK, managed to use the spirit level app @Nick Thomas suggested. Took me a minute to realise that I didn't look for 2 degree angle but 2 percent slope. (which is, if you're using a 1m measuring stick, about 1.2 degree)

 

To be clear though - if a patio is not 2%ish slope, would you all consider it poorly designed and/or something I can complain about?

 

My result is as I expected which is that my patio is pretty much flat, maybe 0.5% slope at best.. 

Edited June 24 by puntloos

[puntloos]

Ping? 😃 sorry but the last question is quite important since I might have a difficult discussion with my builder:

 

Is it reasonable for me to expect a 2% slope patio or should this have been agreed previously?

Edited June 26 by puntloos

[Buzz]

7 minutes ago, puntloos said:

Ping? 😃 sorry but the last question is quite important since I might have a difficult question with my builder:

 

Is it reasonable for me to expect a 2% slope patio or should this have been agreed previously?

Yes it is reasonable to expect a fall on your patio and your paths too, the only thing up for discussion would be where to have the fall if not obvious but as you have a french drain I'd have thought that was a big enough clue and shouldn't need pointing out .

[puntloos]

Just a quick update, I had a garden guy over (not really an 'architect') but to his understanding patios should be angled away from the house and 'into the grass'. Of course with my grass being on top of pretty serious clay he wasn't 100% sure. My contractor says they did a "1:80" slope (which is 1.25 percent) away from the patio, but as far as I can tell at best it's flat. 

 

So I am certainly still confused. The patio is porcelain tiles though so it wouldn't be a huge problem with eg weeds/fungus taking hold. 

[ETC]

On 23/06/2024 at 16:49, puntloos said:

My current patio keeps standing water, even though there's a french drain next to it. 

Does this mean the tilers didn't put down an appropriate angle? A "random video" online tells me that for proper draining you need at least 2%, so 2cm per 100cm? Or is it not standard to angle outdoor tiles a little?

 

What's an accurate way to measure the drain angle of the patio? 

 

Or can I just from this picture claim the patio isn't angled appropriately?

(for what it's worth the scaffolding planks might've stopped some of the potential draining, although I imagine water would find a good way around it?)

 

 

Drill holes through the slabs or joints - let the water drain through;)

[G and J]

Isn’t this a classic problem for a water level?  You’ll need a friend, some wood, some cable ties, a clear tube, a funnel and a marker pen, and of course some water. 
 

Cable tie the tube to the bits of wood so when each piece of wood is stood either side of the patio the tube forms a big u shape.  Full tube till it’s at a sensible level to mark the level on both bits of wood.  Dismantle, put the bits of wood next to each other and measure the difference between the two marks.  
 

Do lots of maths to calculate angles, sigh, then shrug and accept that it is what it is and dig a small French drain between the patio and the grass.  
 

Even better, forget all but the last bit. 

[puntloos]

2 hours ago, ETC said:

Drill holes through the slabs or joints - let the water drain through;)

Sadly I think the underlying clay will have a different opinion on that one...

[Gus Potter]

On 23/06/2024 at 17:35, Ferdinand said:

The surface of the water will be perfectly level, so you can judge the gradient of the patio it by measuring the depth of water in mm at each end.

If the measurements are too small to measure easily, add more water ....

Love this solution.. so simple but very accurate!

[puntloos]

Many sources on the internet (...) eg https://forums.moneysavingexpert.com/discussion/6467233/patio-slope-towards-house seems to claim 1:80 away from the house seems reasonable, but it might be somewhat old knowledge, in particular if people don't have french drains.

 

1/ You don't want water pooling against the house, so angling away makes sense, but  we specifically have french drains to catch water, I can imagine angling toward the house would be logical in my case?

2/ As far as we can tell the patio is essentially flat. Some angled a little one way, some angled a little the other. (strange).

3/ Our grass is a little high 'above' the patio, perhaps the soil of the turf is 0.5-1cm above the level of the patio. It sounds somewhat 'sensible' that this might push water back but on the other hand wouldn't it literally act like a sponge and possibly even suck water in?

 

End of the day, still trying to figure out what's reasonable, my best guess is that "flat" is unacceptable, and the choice of angle towards, or away from the patio both has some pros and cons, but given I have a french drain that's directed to my underground water tank, it would be reasonable to expect it to go into the french drain. Given that (and given the concrete, then clay foundation) it seems like drilling a few holes wouldn't make a big difference. Would re-laying the patio be the only solution?

Edited July 22 by puntloos

[BotusBuild]

On 23/06/2024 at 17:25, joe90 said:

If you want 2% use a 1 mtr piece of wood, stick a 2cm little block one end and put your sprit level on it on the patio (block lowest end) and the bubble should be central. This will give you an idea of the slope (or not).

Or, gradually add 2p pieces until you get level, then you can measure the depth of 2p pieces. If it's 2cm (10x2p pieces), you've got a 2% slope. 

Other coins are available.

[puntloos]

Just reviving this thread one more time to make sure my brain is set out straight. Would you agree that:

 

- If the house has no drains, it's reasonable to angle patio away from the house, to prevent standing water to seep into the foundation

- If the house has a full french drain around its perimeter (that goes to rainwater harvester), it's reasonable to angle the patio toward the drain to catch the water?

 

tx

[saveasteading]

10 minutes ago, puntloos said:

Would you agree

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