How To Handle Excessive Rain Water Runoff

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I am in the process of purchasing a home. It was built in October 2018. In February of this year, there was a pretty severe rain storm that dumped way more than the normal amount of rain in a short period of time. The home is built on a slope. The rain gutter system was overwhelmed it seems and there was some water intrusion at the foundation at one end of the house and rear door to the garage at the other end of the house which is built under the living space of the home and on the downward side of the slope.

Would there be any issue extending the square corrugated aluminum gutter pipe where it comes out from the roof at ground level to channel the water farther away from the house and farther down the slope to ensure the runoff isn't pouring out close to the foundation ? Maybe just 10-15 feet or so. It looks like Lowes has some flexible ABS product called Bend-A-Drain in a 4" x 25' length for about $26 that would do the trick.

I'm also thinking for esthetic reasons maybe trenching those sections of pipe and burying them a few inches underground and then when they exit have them pour out onto one of those splash blocks to diffuse the water stream somewhat.
 
Extensions aren't going to help if the actual gutters are being overwhelmed with rainwater. Grade the area with a steeper slope away from the foundation to move more water away, or increase the size of the gutters.
 
One, two or all three solutions.

A curtain drain can help Maybe 20' from the house in kind of a "C" around the house.

Footing drain around the house at foundation level. They should be 4" PVC pipe, not the cheap 4" flex pipe that gets crushed when back filled.

6" gutters with the downspouts leading to underground pipe that brings the water past the house going downhill.

You will need to get a raincoat on the next time it rains and check things out. Maybe the gutters are clogged?
 
Originally Posted by Dwight_Frye
I am in the process of purchasing a home. It was built in October 2018. In February of this year, there was a pretty severe rain storm that dumped way more than the normal amount of rain in a short period of time. The home is built on a slope. The rain gutter system was overwhelmed it seems and there was some water intrusion at the foundation at one end of the house and rear door to the garage at the other end of the house which is built under the living space of the home and on the downward side of the slope.

Would there be any issue extending the square corrugated aluminum gutter pipe where it comes out from the roof at ground level to channel the water farther away from the house and farther down the slope to ensure the runoff isn't pouring out close to the foundation ? Maybe just 10-15 feet or so. It looks like Lowes has some flexible ABS product called Bend-A-Drain in a 4" x 25' length for about $26 that would do the trick.

I'm also thinking for esthetic reasons maybe trenching those sections of pipe and burying them a few inches underground and then when they exit have them pour out onto one of those splash blocks to diffuse the water stream somewhat.


Any trees around the house? Gutters getting clogged is a likely possibility.

Also, I've dug trenches before with taking rain water away from my house with good effect BUT I foolishly used the plastic "ribbed" type and not smooth PVC pipe. Over time, the ribs can get clogged and can also collapse while the PVC will not. On new house, I used PVC pipe (4") with good effect to pipe gutter water 10' or more down-slope away from my house (I have a crawl space).
 
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The home inspector noted that the gutters should have screens or guards installed to keep pine needles out of them. I will hire a local company to clean the gutters and install guards prior to the rainy season.
A landscaping contractor said he could install French drains around the two sides of the foundation that a lot of the roof runoff was going onto. But a cursory look at the system seems to indicate that if the gutters were filling up with rainwater to capacity, water was probably flowing out the downspouts like a fire hose right next to the foundation. If I can divert that just a few feet I'll probably be ahead of the game.
I think the suggestion to go outside for a look-see during the first good rain should give me an idea of just how complicated the job may be. A section of 4" x 10 ft PVC pipe only runs around $20 so it shouldn't be a major expense if just keeping the downspout water exit point away from the house at a couple of points will help mitigate the problem.
 
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Check to see if the gutters have shifted and no longer slope toward the downspouts. Check for partially plugged downspouts. Pine needles will plug most gutter screens making them useless. Cut down the pine trees..
 
The ground *must* slope away at a steeper angle, to prevent these issues. While your roof concentrates a lot of rain to the house wall boundaries, the lot also collects water. All of it has to be channeled away from the foundation.
 
If your ground is sloped away from the structure, you're already ahead of the game.

What I do with my downspouts if there's no under ground rain water plumbing to tie them into is dig a trench headed away from the house to bury an 8ft section of 4" PVC drain pipe. Put an elbow on the downspout end to route the downspout end into a tee on the outflow end. I dig a hole at the outflow end and bury the tee in crushed stone. Keep one end of the tee at the surface with a slotted/grated cap on the top for water that won't absorb into the ground and so you can clean it out. The bigger the pit or channel you want to dig and fill with crushed stone, the better. You don't have to bury the pipe very deep at all. I put them just a few inches below the surface.

In regards to sections of roof that over-run the gutters during torrential rains, I get that happening at with my home too, but it's not often. Larger sized gutters and downspouts would be the only fix. I'm too cheap for that! lol

Gutter guards suck. Best they'll do is slow the process of the gutters clogging, then when you need to clean them, you have to remove the guards to do so. I've tried everything from commercial ones to the plastic snap in ones. Small debris still builds up over time and the surface of the guards clog over time. Hard rains can run right over the top of them as well.
 
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