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Discussion Starter · #1 · (Edited)
During heavy rains in the Galveston County, TX area my covered back patio floods about 2-3 inches. How can I fix this?

Two possible answers that make sense to me:

First

I have a large roof that can collect a large amount of water. Between the garage and the house it seems the gutter gets overrun. I could add another downspout? This would have to tie into some sort of drain.

Second

I could expect my gutters to get overrun during very heavy rains maybe a few times a year. I need somewhere for the water to go. This would be a French Drain?

I have a link to a sketch and pictures of the flooding.

http://imgur.com/a/sBvlK

In my sketch I have put 'x' for the new French Drain line. This would be about 100 feet total. The 'A' symbol would be for the new downspout.

Any advise would be welcome as I have been dealing with this problem for the last 5 years.

Thank you.
 

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It sounds like you have inadequately sized gutters and downspouts. We had this problem in our townhouse development and all gutters and downspouts of a larger side and not the typical residential size. Be aware that when you get your heavy rains the downspout discharge will be rather large for a short period of time. You may need different splash guards at the discharge (if you have a surface discharge).

Use solid wall pvc (not corrugated or perforated) to get water away. Perforated pipe is to collect and/or distribute water.

With good seamless gutters, it will work like a vacuum to get the water off the roof.

Dick
 

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First order of business, decide where the water will eventually go (dry well? street?)

Then regrade the land or install pits with sump pumps to get the water over to that place.

Note that a French drain also needs a destination for the water. The same construction (same perforated pipe and gravel) with no destination is called a leach field.
 

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Discussion Starter · #5 ·
It would go to the street about 90ft away. It would be an L shape route since I dont have a direct shot. I can probably get the grade right on one side, but not the other.
 

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We solved our overflow problem with larger gutters, but because all of the roof water is carried away but, the discharge from the larger downspout was rapid and can cause erosion.
Your rain storms can contain a lot of water, and I think they maybe be pretty rapid or short duration at times.

Dick
 

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Bombastic Idiot
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WARNING!
This turned out to be way long , detailed, and complicated, but it's raining an I got nothin better to do, except things I SHOULD do. Every time I thought of something I thought of some thing else. Sorry.

Bigger and more downspouts should help especially if you have the too common 2X3 spouts, the big boxes have 3X4, larger sizes from gutter specialists. You can also use thin wall PVC pipe. Big boxes usually don't have any thing but 5" gutter, which is actually about 3 across the bottom and up the back with the front sloping out in that ogee shape (called K style) to about 4" across the top. Larger sizes from folks who do commercial work. Usually larger down spout is more effective than larger gutter except on long gutter runs.
.You do need a spout in that corner, due to the geometry, an inside corner often winds up being too low. And it looks like it is at the bottom of a valley. A lot of water comes rushing down a valley and can over shoot the gutter. You may need a diverter extending up on the outside of the gutter, but they trap debris behind them you can also put a diverter(s) higher up the valley to send the water away from the corner. I am getting way to complicated here, you pro'lly don't need to go to such extremes, cept mebbee a small diverter at the corner.
A couple more spouts wouldn't hurt.One on the garage corner between your 1 and 2, My rule of thumb has been to put a spout at each outside corner of a roof, another one opposite A, that is, 'down' on your great drawing, at that small outside corner. The less water going to A the better.Don't know where you'd drain that one to, p'rhaps a run of spout angling down across the wall to that very bottom spout, UGLY. BTW where does 2 drain to? If you're not getting flooding from 2, A won't have to drain much farther than that.
Now your “French drain,” as CM said it's not really a French drain, which is the perferated type used to collect and distribute ground water, we're talking about surface water. The patio could use some more slope away from walls and corners, but we got what we got. You got all kinds of what look like floor drains and capped off pipes are those part of the swimming pool system, where do they drain to, back to the pool and the sanitary sewer? If so we can't use them to solve the issue. Is there a slope toward the rocks? What is that black circle in the 'rocks'? It sure is tempting if its a drain. Could it be disconnected from the pool, the top lowered, and rerouted? The whole rock area looks like a good collection point for drainage if the patio just slopes a bit toward it. At any rate get the rocks and gravel out, dig and grade the bottom to slope towards the side walk at 2.
( HOKEY SMOKEY!. I just saw in pic two electrical(?) wires. Ground wire, phone, cable? What ever that's not good in the water.. Sorry for the interruption, but...)
Any way grade the bottom as far below the bottom of the side walk as the outside diameter of your SOLID thin wall drain pipe. If we can use it as a collection point make sure there are no jaggedy rocks, roots, broken Scotch bottles, knives nor fossils in there. Cause we gonna line the inside with some really thick plastic sheeting, one big piece is best, pond liner is better but costlier, I once used an old water bed, not the liner, the water bag. Got one of those around? If no collection just dig a trench deep enough for your pipe from the spout.to under the walk.Figure out where 2 is gonna connect. Tunnel under the walk, trench from there to your discharge point.You want a slope of at least 1/8 “ per linear foot, 1/4” is better, more is even better, you want the top of your discharge to be below the bottom of your collector, if just a spout drain below the bottom of spout. Slide your pipe under the walk, a piece a couple of feet longer than the width of walk is easiest. Connect pipes on each end, to spout and discharge, trenches , pack soil and gravel in tunnel, refill the rocks.
I best stop. I was gonna get into detailed instructions for tunneling lining the collection box filling with the right gravel, warping time space continuum and who knows what. Sorry about that. Mebbee you could just toss a humongous sponge out there.
I DO wanta compliment you on the pics and especially the drawing, some verbal discriptions of problems are more confusing than my answers.
 

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Discussion Starter · #8 ·
Wow

Thank you for your detailed response. I will reply with more detail later as I am on a mobile.

I like the diverter idea that can help with that valley. I need to update my drawing with roof ridges.

Are you saying I can use PVC for a downspout ?

2 simply drains across the walk to the yard with no flooding.

The two "circles" in the rocks, one is a gas hookup for BBQ another is a drain for a failed french drain I was trying to make. So underneath those rocks is a corrugated 4 inch pipe of fail.

Yes that is a ground for a breaker box in the garage on the other side of the wall.

I will respond more with more detail tonight, but I think you got me on the right track!
 

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Discussion Starter · #9 ·
I am having a gutter pro come out to give me quotes on adding more spout on point A and between 1 and 2, and a diverter. I am researching prices on the lining for the under the rocks. Moving out all the rocks and adding the liner seems like a lot of work. I may hire out for that too.

I will update with new pics as soon as its done. Thanks for the help!
 

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Bombastic Idiot
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I left out the very first step. Are you sure the water is coming from that corner? We may be spinning our wheels and spending money we don't need too. Look around and see if the water could just be running in from else where, just across the yard and pool apron.
Moving rock is hard labor for sure, that's why they got laborers Putting in a liner is easy as making a bed, just take your time and be particular about corners , in fact you make inside out hospital corners. The liner itself can be nothing more than heavy mill black plastic, they got some in the garden section. Its purpose is to make sure water runs down to the outlet and doesn't just soak into the bottom making a muddy mess or puddling up under the gravel and stagnating. The bottom under the liner doesn't have to be perfectly graded or even smooth, just no real highs and lows that would become too much of a puddle or anything that would poke a hole in the liner.
But do take a good look around and eliminate all possible sources of water B4 spending any money. Get estimates and opinions from gutter folks and also landscapers experienced in drainage about the whole hole under the rocks and drain lines. I am no expert just experienced in moving water around my place, you haven't had any water come over the sill and into your just layed laminate flooring have you? That was a mess. I grew up in the Panhandle, rain was something we read about in books, now I am in Dallas area and we can get a heavy rain that lasts a while and doesn't immediatly soak into the ground. It's real easy for me to sit here and blather on about what you should do, I won't pay any consequince if I'm wrong. Get advice and estimates from pros who are right there on the scene. Good luck and let me know how it works out and how wrong my advice was.
 
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