Roof Vignette - Gutters and Downspouts

[krissmZ]

Does anyone have any clear understanding on when and how many downspouts should be used? Is there a rule, like if a gutter is under 3' long then only 1 downspout is required vs. needing 2 (1 on either end of the gutter)?

Also if we have a situation where the gutters meet at the corner, does NCARB read the 2 separate gutters as 1 and therefore only 1 downspout is required as shown in the image below?

NCARB - ROOF - ZARELLA - question about gutters and downspouts.jpg

[Coach]

Does anyone have any clear understanding on when and how many downspouts should be used? Is there a rule, like if a gutter is under 3' long then only 1 downspout is required vs. needing 2 (1 on either end of the gutter)?

Up to 15', one. Otherwise, one at each end.

Also if we have a situation where the gutters meet at the corner, does NCARB read the 2 separate gutters as 1 and therefore only 1 downspout is required as shown in the image below?

Gutter should match edges of roof, so don't cross at outside corners. Don't share downspouts.

[OBJD]

You're saying to use more than one downspout for a gutter longer than 15', and yet the "Sample Passing Solution" from the NCARB guide is only showing a single dnsp. on the 18' long eastern eave of the lower roof... what am I missing here?

[Coach]

It's just a guide. Frankly, one per plane is probably enough.