6" Gutter Question

carlspackler

Wondering what the maximum run can be for 6 inch gutters with 3x4 downspouts. Do turns affect this number? Also, what would it be for 5" gutters?

Shingle Monkey

My gutter guy will do runs up to 100' continous. With 1 down spout to 40' max.

Theres factors to everything though.

carlspackler

Not sure I follow the math. 100 foot continuous but 1 downspout to a 40' max? Doesn't that negate the 100' continuous run with a downspout every 40 feet?

IOW, wouldn't that be a 40' continuous? Or are you talking about seamless with 100'?

Grumpy

While we don't mind doing 100' gutter runs when necessary I have read many "guidelines" which state that an expansion joint should be placed every 40' or so. FYI, I think SM was referring to the continuous being synamnous with seamless.

Our rule of thumb under typical situations is one 2x3 downspout for every 35' of gutter. I don't care if it is a 5" or 6" gutter. However having said that rules of thumb are all hogwash anyways. Check out this link: http://chrisind.com/calculating.htm

carlspackler

Thanks for the link. That's good stuff.

Would you think though that a 6 inch gutter (which holds 70% more water than a 5 inch gutter) should be able to run longer spans before requiring a downspout (which would be bigger too at 3x4)? Just seems logical to me.

Grumpy

Carl. I suppose in theory Yes it could hold more water, but a gutter is not designed to hold water. A gutter is designed to catch the water from the roof and direct it to the downspouts for drainage. You really don't want the gutter to become a retention pool holding excess water that the downspouts can't yet handle This is going to lead to alot of problems with snow and ice.

Also remember you want about 1/8" slope on the gutters for proper drainage. This is why we have come up with the 35' rule. Do the math, 35' of gutter at 1/8" slope = a difference of more than 4" in height on the length. Anything more than this looks very goofy or you have to decrease the pitch of the gutter which can be problematic and lead to call backs.

Remember once putting logic/theory into practice, it isn't always logical anymore. Lots of things which look good on paper, don't work in the real world.

AaronB.

I use the 1/4" per 10' method and this has not yet failed me.

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gutts-1

It really depends on sq. roof area. On a regular res. house when you hit 35' start looking to add another d.s.. a 35' peice broken with a bay window i would have two.