Patio and Pool Decking Drainage

I am getting very confusing estimates on re-doing our existing kool deck with pavers in regards to drainage.

One contractor says no drain is needed and others have a two inch deco drain going in.

Please help. Do we need a drain or is slanting the pavers somehow enough?


ANSWER - Patio and Pool Decking Drainage

To answer your question properly, I would have to know the elevations of your property. However, to be more practical in trying to answer your question, consider the following.

Water has to go somewhere. You do not want it sitting on your patio. Ideally, the pavers would pitch in the direction you want it to go at 1/4" per foot. Some contractors will do less but I like to use 1/4" to be on the safe side.

Assuming it is pitched properly and drains off your paver patio or pool decking, then where does it go? Can your ground be graded to direct the water to a lower area on your property? This might be easy to do, or perhaps you might need a swale.

Ask the contractor who is just pitching the pavers where the water will be directed after it goes off the patio. At the same time, ask the contractor who wants so use the drain, why he is suggesting that, and where is the water from the drain being directed.

Basically it is a matter of directing the water in a more natural way or being forced to use drains due to a more or less flat property.

I know it can be confusing, but I hope this was helpful.


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Jan 28, 2010
Patio Drainage Problem
by: Susan

I don't think that is a good solution and I'm not sure what you can do about this problem.

If you drill a hole in the concrete, there is a good chance the surrounding concrete will crack. If it worked you could possibly fill the hole with gravel to allow the water to drain. However, this opens up the possibility of the water then seeping under the patio and compromising it's stability.

If it's not that bad, you might choose to live with it. Your other choice would be to remove the patio and install a new one that is pitched properly for drainage.


Jan 27, 2010
front pourch drain
by: Anonymous

I have a front patio already pored. It puddles in the middle, and I would like to drill a 10 inch diameter hole thru the cement and dirt. Then what do I put in the hole so the patio drains? It doesn't get a lot of water because there is a roof over the patio, but some water does blow in. The house foundation and the front lawn is higher that the patio.

Nov 07, 2009
Drainage Pipe and Drywells
by: Susan

Hi Lee,
I think you are referring to what I know as either a trench drain or perforated pipe. Correct me if I am wrong. Either way, the water enters through the top of the pipe. The pipe is pitched in one direction and the water drains to an appropriate area. In your case, I believe you are saying that there is no where else out of the way to drain it to, so you just want to end it in a lawn area...therefore the drainage pit.

Could you extend it to another area so that the drainage pit would not be necessary? I'll assume you cannot.

I think you are better off with a grate over it to allow the water to enter freely. I believe lawn will just give you problems. You can also purchase an actual "drum". The water would enter into it and percolate out through holes.If you have further questions or need to clarify anything, just post here under Comments.


Nov 05, 2009
deco drain drainage
by: lee Watts

hi susan, i was happy to see a possible place to get an answer to my issue. i am having my pool deck resurfaced, in the process the deco drain is being replaced with the 3.75 wide model with the removable top. i have been told that it would enhance my drainage if i were to dig a "dry well" filled with gravel at either end of the drain. at one end i have no problem since the landscaping is already a desert type with gravel on the surface. the other end however ends up where my grass is, i would like your opinion. should i dig the dry well, fill it with gravel and leave that open, do the same but recover with grass to make it more attractive or install a grate/grill over the dry well?
thank you,


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Paver patio and clearance for exterior wall weep holes

by Chuck
(Houston, TX)

I'm considering installing concrete pavers on top of an existing concrete slab patio. The concrete slab is against the exterior of my house - a brick wall. What is the minimum space that's required between the bottom of the weep holes on the brick wall and the top of the new paver patio? This would determine whether I can put the pavers on top of the slab or whether I would need to remove it.

If I installed the pavers on top of the concrete I'm thinking there would be 1 7/8 inch clearance between the top of the patio and the bottom of the weep holes. This is based on the following measurements:
4 3/4 inch -> top of concrete patio to bottom of weep hole
2 7/8 inch -> 2 3/8 inch paver + 1/2 inch of sand
... equals
1 7/8 inch

Other details:
The wall has an 2 ft eaves with a gutter.

The patio is planned to drain horizontal to the wall towards our driveway. Currently there is pretty good drainage, but I think it drains a different direction - toward my backyard.

The paver patio is planned to be bigger than the concrete slab, so part of it will be on soil (with compacted sand, etc).

I live in Houston, TX.



Hi Chuck,
Landscaping drainage will be one of your main issues. I have never seen brick on a house with weep holes. I can only assume that this is a planter.

Without knowing for sure, I would say that 1 7/8 inch clearance is OK. I think it would depend on how much water is being released from the weep holes. I say this because in a worse case scenario, the water would come gushing out and raise so quickly that it would be at the level of the holes. I think this is unlikely.

If you are changing the grade direction and per cent of slope, be sure that you grade at minimum of 1/4" per foot. Installers will do less, but I go with this to be sure of proper drainage and water flow. Again, if the amount of water coming out of the holes is minimal, leading the water towards your driveway is probably OK, but why are you changing the direction? You might be able to fill at the edge of the patio towards the back. It's usually better if water goes into the ground rather than onto a paved surface.

There are many unknowns and these are just my thoughts based on the information you provided. If you have any follow up comments or questions, just post them here.


P.S.I am also wondering where your gutters flow to.

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Drainage Problem

by Steven

I have an unfinished basement that has a sump pump. I have a small backyard with a vinyl in-ground pool that takes up half the yard and the deck takes up the other half.

Every time it rains (heavy) the basement floods. The water enters from the half/escape window. The drains in the sump-pump don't drain according to the amount of water pouring down.

Would a paved (brick) landscaping job with a covered drainage ditch to channel the water away from the basement be advised or do you have other suggestions? i would like to finish my basement.

Thank You

Comments for Drainage Problem

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Sep 26, 2008
Patios and Drainage
by: Susan

Hi Steven,
It's difficult for me to give an exact solution without seeing the property and knowing what your existing elevations are.However, I can give you some general input.

The grade against the house must slope away from your home at 2% or 1/4 inch per foot for a distance of a minimum of five feet. Then...this water must be directed somewhere. It might be part of a swale system or it might lead to a drain.

I don't like the ideas of a drainage ditch against the house. People sometimes install french drains there though. Perforated drains are installed which lead the water away. These drains are beneath the ground....the water seeps into the pipe through the holes. The drains are sloped along the length of the house and the water is led away.

If you want to add a patio up to your house, slope it away from the house and make sure the water has somewhere to go.
Otherwise, you can add a planting bed along the house. Further out could be a swale or drains.

It will be worth your while to contact a professional engineer, qualified landscaper, or landscape designer or architect, to make sure it is done correctly.

I hope this was helpful.


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Patio drainage design

by Chris
(New Britain, CT)

Patio Drainage Design
I am building a patio that is 12' x 14'. I can't really slope the entire patio away from the house because the land slopes slightly towards the house. I am thinking of placing a storm drain in the middle of the patio that will act like a "funnel" too keep standing water from forming. (This drain will tie into the already existing 4" diameter pipe that connects to the city drain.)

My question is: Will one drain be enough for a patio this size or should I place more drains in different areas of the patio? (Or alternatively, is there a formula for how many drains are necessary per square foot of patio?)

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Jul 07, 2009
Landscape Drainage Pipes
by: Susan

In order to follow my suggestion then, you would have to re-grade the area.

So going back to what you want to do, I believe you are referring to a trench drain. Try to get one in a color close to your patio color.

I would definitely contact either a very reputable landscaper or an engineering firm. Pipes are sized to handle all water that will go into them. This is not only surface water but can also be roof water. Ever if you have roof leader pipes/drains and they lead into the other pipes, if the trench drain pipe leads there, then more water is going into those other pipes. In addition, the trench drain pipe size must handle the water it will receive. There are mathematical calculations for this to do it correctly.

I don't think you are wrong at all to be thinking about this. Better safe than sorry.



Jul 06, 2009
Patio drainage design
by: Chris

Thanks for the tip. I thought of doing that and still could. The problem with that would be that to slope the patio the proper amount would make the end of the patio that meets the decorative stone about 2.5 to 3 inches below ground level at that point. I'm a little hesitant to do that for fear of water pooling there during heavy rains.

Unfortunately, the land slopes slightly toward the house and the top of the foundation is at the same height as the land or slightly below it. The patio will also abut my driveway which also slopes toward the house. (I know a picture would give you a better idea, but I don't have one available. Plus the pitch of the land may not be visible in the photo.)

I'm not too concerned about the aesthetics of one or two of those 6" black plastic drain covers attached to the pipe or pipes in the middle of the patio. That was factored into my plan anyway. I'm probably overthinking my design, but I'd rather be overly cautious to prevent water from entering the basement.


Jul 06, 2009
Patio Drains
by: Susan

Hi Chris,

A couple of things....

There is a formula which pertains to the amount of water a pipe will capture and how large the pipe should be. I can't recall where to find this, but you might contact an Engineering firm as they do this all the time.

Another solution would be for you to install a pipe at the perimeter of your patio. In other words, there is the house, then the patio, then where the patio meets the land a pipe would run along the patio length.

This would be a perforated PVC pipe (hole on the top of the pipe for the water to enter through) wrapped in filter fabric to prevent dirt from getting into the pipe and clogging it. Over this you would place decorative stone. This pipe could then lead to the other pipes you referred to.

The advantage of this is that you do not have a line running down the center of your patio breaking up the design.

Is there any reason this would not work for you?

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Acceptable Water Drainage

by Jake

I have a brick paver patio that was installed and after a good rain we have some puddling. I was wondering, what is an acceptable drain rate on water? Are there any industry standards that say X amount of water should drain in X amount of time?

After 1-2 hours the water is gone.

Hi Jake,
I don't know of any industry standards stating how long it should take for water to drain away, but 1-2 hours is too long in my opinion.

There are, however, standards as to what the correct pitch should be so that water drains away correctly. That is 1/4" per foot, or 2%grade.

In your situation, the severity of the problem would depend on where it is collecting. If it is near your house it's more serious than if it is in the center or at the perimeter.

You could also have them relaid correctly. That is the nice part about pavers...they can be relaid easily.

I hope this was helpful. Please reply if you have further questions.


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