Do I Really "Need" 2 Downspouts?

Old 04-17-12, 02:02 PM
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Question Do I Really "Need" 2 Downspouts?

Hi Everyone,

I'm almost complete with building a detached garage that is 40' long 26' wide. It is permitted so will have to be approved but the inspector is on the nicer side. I will be installing my own aluminum gutters with 10' sections. I keep reading that anything over a 40' run requires 2 downspouts. Once I add in my overhang, I have a 43' run. The thing is, the rear of the garage has great drainage with a down slope into the backyard. The front of it has worse drainage and goes into the driveway (also where the house drains). So it really makes sense to me just to have one downspout at the rear of the garage and slope the gutter accordingly. I am using the larger 3x4"? downspouts.

BTW, the roof is width is 13' (26/2) with a 9/12 slope if that makes a difference for your opinions.

Old 04-17-12, 02:30 PM
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No expert...but thats a darn long run that could collect a massive amount of water. Even with a good slope and drainage in the back it could carve a channel unless you do a dry bed(?) to carry the water.

Have to'd be better finding a company who would roll you out some heavy gauge seamless....the DIY sections have a real tendency to leak and look bad. Every joint is also just a place for debris to collect and impede flow.

The Pro's will be around...this was just my opinion.
Old 04-17-12, 02:39 PM
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I agree with Vic. 43 feet is a lot of water for a 4" downspout to handle all at once. Besides your slope in 43' would be quite noticeable. Not so much if you had it slanted to the two ends.
Old 04-23-12, 07:35 AM
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Ok, thanks for your input guys. I guess I'll stick with one at each end. Maybe I'll slope 1/3 of it to the front and 2/3 of it towards the rear just to force the water more towards the rear.

I have a hard time paying anyone to do anything when I can do it myself. Took me a while to be convinced to let someone install the garage doors! And I've had a decent experience with the 10' aluminum gutters I installed on my house. I think the 4" downspouts really help because they don't get clogged up as easily.
Old 04-24-12, 09:27 AM
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I am currently dealing with my gutters and drainage in the house I bought a few months ago. Being the same as you, I have a hard time hiring someone to do something that I can do.
That being said, the gutters on my house are the 10' sections. Not sure if someone was doing it themselves to save $$ or if it was the only thing available at the time (very old house). Anyway, the point is, most of the seams in my gutter setup are leaking now.
Weigh out the cost of getting the seamless ones done, and think about how much your time and repairs down the road are worth to you. Also note that seamless looks a lot nicer.
The up side for yourself is that the garage won't be too high to work on. My house is 3 stories high, which is not fun tied off or working from a ladder.
Old 04-24-12, 09:29 AM
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I'm with Mike - I hire gutters done to eliminate the seams.

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