too much gutter, nowhere to put downspouts

[mariepierre]

I have an "L" shaped ranch -- the long part ot the L is the house and the short part is the garage. The entire inside of the L is filled with driveway. There is one downspout at each end of the L and the space between runs about 80 feet. In spite of 6 inch gutters, the downspouts cannot handle heavy rain and the water comes gushing over the top of the gutters near the downspouts in heavy rain.

Is it possible to put two downspouts next to each other? Is there any kind of "supersized" downspout I could use instead?

Thanks for your thoughts.

[AJDupree]

I assume you have the standard 2x3 size downspouts? There are larger

3x4" or 4x5" (can't remember which) commercial size downspouts, but you'd also have to make sure that the hole going from the gutter down into the downspout is larger also, otherwise it would still bottleneck.

[yellowbirddog]

I'd bet that your downspouts are clogged or they run into a clogged or inadequate drainage system.

If your downspouts and drainage systems are working properly, they should be able to easily take as much water as your garden hose can throw at them all day long. Look into a open-end drainage system that drains into a safe area far away from your foundation if you don't have such a system already.

Downspout strainers would help keep debris out of the drainage sysytem.

[JimL]

Sure you can.

Or you can just increase the slope.

[dpb]

...

...

While _possibly_ a contributing factor, an 80-ft run between downspouts is too long, especially for a 6" gutter into a standard 2x3 downspout...

I'm willing to bet OP's will take several garden hoses' full output as they are--that is absolutely nothing in total output as compared to a heavy downpour. ...

Another poster noted there are larger downspouts that can replace the existing ones and noted a bottleneck unless the gutter opening is also enlarged to accomodate. A second potential problem would be if the downstream drainage is unable to handle the larger flow--it isn't provided whether there is a ground drain or whether they just empty onto the driveway.

If the downspouts are running over already, the suggestion of more slope won't help--getting the water to a bottleneck faster won't clear the bottleneck.

Cheapest first-try fix is the larger downspouts at the existing location--the second at the end will help some but installing it would cost essentially the same as the larger and the one would undoubtedly look cleaner than having a second.

If that still doesn't provide sufficient drainage the next thing would be to add another in the middle (or as near as possible based on window placement, etc.) of the run.

[yellowbirddog]

I mentioned garden hose flow (with the word "easily") to suggest a quick test. If a downspout can't take a garden hose flow for an extended time, there is definitely a problem with it or with what it is connected to. Start with the simple and easy issues first.

[Jim McLaughlin]

I'm reading your post that the gutter is highes at the mid point of he run, and slopes downward 40 feet in each direction to a downspout at each extreme. High point may not be in the exact middle, but that is probably a close enough estmate. It may be 60 feet for the hudse and 20 feet for the garage, with the high point at the apex of the "L".

I had a "Z" shape gutter run with one downspout at one end, with a 60 foot run. The little middle leg connecting the It was a disaster regarding runoff.

I had to first "Roto Rooter" out the pipe to the dry well, then replaced the gutter entirely with two separate runs, and add d three downspouts. Also had to pipe runoff from downspouts to a second drywell. It wasn't cheap and was a pain to do, but livimg here in the Pacific Northwest (Oregon, Willamette Valley) we get a lot of rain concntrated from late October through April.

Now have two straight sections, with a downsout at each nd of each section, all piped to dry wells.

I am the third owner of this house, lived here since 1980. House built in

1968.

I'd really like to gett my hands on the original builder an architect. I have two separate nooses with their names on them.

[yellowbirddog]

Here's an article that can help you calculate an optimal drainage setup for your gutter:

[Jim McLaughlin]

Good site. Nice data.

I got lucky with my project, gut instinct got me a result a little more efficient than that obtained by using the formulas.

[dpb]

Well, that wasn't (and still isn't the slant I got when I read your actual wording, but ok. There wasn't any indication in OP's post of any problem except in really heavy downpours nor that there is anything except a concrete driveway on which they empty.

I was simply making the point that even if the downspout can accept the output of a garden hose (or two or three) continuously that really doesn't mean it won't backup in a heavy downpour. Of course, if it is plugged up and a garden hose _does_ show it, yes, that's a problem...

And, OP told us roughly how long the gutter run was but nothing about the size of the roof it was draining so there's no way to estimate the accumulation rate during a frog-strangler...