patio standing water on concrete under rubber tiles

grassylawn

We have interlocking rubber play tiles on concrete. The concrete has a gradient towards surface drains, but it is imperfect and there is shallow stagnant water in places under them. We have a lot of midges around the play tiles at the moment and we think they are breeding in the water underneath. I can see what looks like larva in places where the water puddles. There is also small amounts of mud under them and between them. There is also a drain that leads to out septic system under an outdoor tap.

I think this problem is similar but not the same to standing water under decking, so possibly a solution that has worked for one would work for the other.

I plan to power wash the tiles. Lift them. Power wash the concrete underneath. Observe where the water pools. Then do -something- to stop it pooling again.

Idea 1:
I believe that putting down coarse sand would fix the problem. I think I would need to make some concrete ridge around the wastewater drain to stop it from washing into that. I don't know how much might get washed into the surface drain and whether that might cause problems. I think I would be unable to wash the area because of it washing the sand away. I would also need to avoid emptying large amounts of water at once, for example if a large container was filled with water for toddler play or being left in the rain. I think normal rainfall probably wouldn't wash sand away.

I might look into putting filter fabric over the drain (which is under the tiles) My observation with filer fabric is that it slows the flow rate considerably which might not be ideal.

Idea 2
Use an outdoor levelling compound to raise areas where it is pooing. This might be easy or difficult depending on the size and shape of these areas. Obviously this is somethign I need to be careful to avoid letting into drains.
I suspect it is quite a large area.

Ideas/insights/advice/experiences?

listermint

ideally those tiles should not have been laid on anything but level or purposefully slanted concrete (drainage) as water will get in and around and under them. So you'd need to have a good course for the water to leave (exit)

Putting sand in will not help as you will have concrete under neath thats not permeable enough. The most ideal situation would have been a hardcore compacted and then a sand on top then your tiles. But you are where you are.

I think you need to level out the low spots ensuring all water is directed to a viable drain.

grassylawn

listermint wrote: »

ideally those tiles should not have been laid on anything but level or purposefully slanted concrete (drainage) as water will get in and around and under them. So you'd need to have a good course for the water to leave (exit)

Putting sand in will not help as you will have concrete under neath thats not permeable enough. The most ideal situation would have been a hardcore compacted and then a sand on top then your tiles. But you are where you are.

I think you need to level out the low spots ensuring all water is directed to a viable drain.

Yeah I'm annoyed that it was done on concrete. Absolutely not my preference but I was busy with work and didn't involve myself enough with the project at the time, and the builder basically refused to do it differently. There is a slant, but like i say it is not working great.

I know the sand won't improve the drainage. The idea with that is to remove any pooling. The larvae are water borne so they can breed in puddles but not in wet sand. Having it run off would be better than having it wet though I suppose, one way or another.

Would it nmake sense to seal the slab with pva so the water rubs off instead of soaks in, ince it is level. The rubber basically insulates it from the sun so it doesn't dry out quickly at all.

johnb25

grassylawn wrote: »

Yeah I'm annoyed that it was done on concrete. Absolutely not my preference but I was busy with work and didn't involve myself enough with the project at the time, and the builder basically refused to do it differently. There is a slant, but like i say it is not working great.

I know the sand won't improve the drainage. The idea with that is to remove any pooling. The larvae are water borne so they can breed in puddles but not in wet sand. Having it run off would be better than having it wet though I suppose, one way or another.

Would it nmake sense to seal the slab with pva so the water rubs off instead of soaks in, ince it is level. The rubber basically insulates it from the sun so it doesn't dry out quickly at all.

How about cutting a few grooves into the concrete from the pools towards the drain. Angle grinder and stone disc should do it.

listermint

johnb25 wrote: »

How about cutting a few grooves into the concrete from the pools towards the drain. Angle grinder and stone disc should do it.

Or drill a load of holes right down through it and fill with sand.

grassylawn

listermint wrote: »

Or drill a load of holes right down through it and fill with sand.

I just got that exact suggestion from the supplier of the rubber tiles.

grassylawn

I thought of drilling holes before but I read that they fill with water and then freeze, expand and crack the concrete. I suppose the sand stops that from being a concern though.

johnb25

grassylawn wrote: »

I thought of drilling holes before but I read that they fill with water and then freeze, expand and crack the concrete. I suppose the sand stops that from being a concern though.

Don't think so. Water will still get in. You would probably need to go right through the concrete so that water can drain through.

GreeBo

Are the tiles fixed to the concrete or just sitting there?
If they are just sitting on the concrete then you will never get them dry, capillary action will keep water underneath them after any but if rain and even dew.

Breaking up the concrete surface, would help, but you won't break it enough to solve the problem and still have concrete left!

What's the underside of the tiles like, is it smoothe it had ridges/bumps etc?

grassylawn

GreeBo wrote: »

Are the tiles fixed to the concrete or just sitting there?
If they are just sitting on the concrete then you will never get them dry, capillary action will keep water underneath them after any but if rain and even dew.

Breaking up the concrete surface, would help, but you won't break it enough to solve the problem and still have concrete left!

What's the underside of the tiles like, is it smoothe it had ridges/bumps etc?

Just sitting there. Bumps.

http://black-swan.ie/wp-content/uploads/2021/02/Interlock-Play.jpg

grassylawn

johnb25 wrote: »

How about cutting a few grooves into the concrete from the pools towards the drain. Angle grinder and stone disc should do it.

This would be extremely difficult to get right because of the size of the patio and how slight the gradient is. It is possible that the drain is higher than some of the places where the puddles form.

GreeBo

grassylawn wrote: »

Just sitting there. Bumps.

http://black-swan.ie/wp-content/uploads/2021/02/Interlock-Play.jpg

Did water pool there before the tiles went down?
You might try leveling compound to remove the dips, but be careful you don't remove any fall altogether!

grassylawn

GreeBo wrote: »

Did water pool there before the tiles went down?
You might try leveling compound to remove the dips, but be careful you don't remove any fall altogether!

The tiles went down immediately after its construction.

GreeBo

Id take them up and run the hose over the concrete, see where the water pools and then use an external self levelling compound in only those areas.

grassylawn

GreeBo wrote: »

Id take them up and run the hose over the concrete, see where the water pools and then use an external self levelling compound in only those areas.

Ok a vote for idea 2 so

grassylawn

I've discovered that my preferred solution of just drilling holes at the deepest parts of the the dips won't solve things per se. The problem is that the worst puddle I've found is right against the house. Obviously we don't want to drain a large patio into the ground right at the foundations, especially when they will be pretty dry everywhere else. Direct shallow channels to the drain also don't appear to be feasible because the drain does appear to be higher than the dip.

[We asked the builders to put a drain running along the side of the house, but believed them when they said it would make no difference, but that makes bo practical difference now really.]

My thoughts are to either try to raise it there with self evelli g compound or crete shallow channels to a drainage hole further out from the house.

grassylawn

grassylawn wrote: »

I've discovered that my preferred solution of just drilling holes at the deepest parts of the the dips won't solve things per se. The problem is that the worst puddle I've found is right against the house. Obviously we don't want to drain a large patio into the ground right at the foundations, especially when they will be pretty dry everywhere else. Direct shallow channels to the drain also don't appear to be feasible because the drain does appear to be higher than the dip.

[We asked the builders to put a drain running along the side of the house, but believed them when they said it would make no difference, but that makes bo practical difference now really.]

My thoughts are to either try to raise it there with self evelli g compound or crete shallow channels to a drainage hole further out from the house.

I looked in the drain at the gutter that it is supposed to connect to. It doesn't. The pipe from the patio is about an inch lower than the pipe that leads to the soakpit. They appear to have put a soakpit right against the corner of our house. The water from the gutter is also going into that.

I suppose fill it with concrete and use a water butt for the gutter water. First i want to wait til it dries a but and make sure the pipe that is not getting any water ibto it handles water going into it

grassylawn

Running a hose into the smaller pipe that i took to lead to the original soakaway just seems to result in the water coming back into soakaway that is right where tbe drain is.

Don't know if it is failed or broken or in fact leads into the drain and not from it.

Dug around at the edge of the concrete apron to try to find where it goes but didnt find it.

Confused.