Downspouts for Dummies

Residential gutter and downspout

After one of our staffers lived for several years in desert climates, he moved to the Gulf Coast. The first time he cleaned out his gutters, he was a bit surprised to find big, fat downspouts. He'd been used to the 2" x 3" downspouts common in low-rainfall areas, so the 4" x 6" downspouts on that house near Houston seemed yuuuuge! But at least he understood why: rainfall during tropical storms often exceeds ten inches per hour. Unfortunately, Nicole Schmoll, journalism grad and eHow contributor, was completely bamboozled by the question, "How to Measure Your Downspouts."

Although eHowians get plenty of stupid questions, even Schmoll was smart enough to realize that the OQ didn't want to know how to climb a ladder with a tape measure. That's why Nicole headed for a gutter-sizing calculator... after making one of the most inane statements in the history of freelancing:

"While it may not always be looked at as such, a roof is one of the most essential aspects of a building because it protects the people and things inside of it from inclement weather and extreme heat."

Yeah, duh – though we aren't sure what gutters and downspouts have to do with "extreme heat." Whatever the case, Schmoll wanders through the next few hundred words filled with clumsy constructions such as "Understand that it takes 96.15 square feet of surface with 1 inch per hour of rainfall to correspond with 1 gpm of flow rate," all because DMS demands "action verbs."
After babbling semi-coherently about how to use one of the online calculators – along the way thinking that you need blueprints to know the dimensions of your roof, and that 8500 ft² is a reasonable footprint for a roof – Nicole gets to the meat. First, it's the cross-section of the downspout:

"...you could use a five-inch diameter plain round, corrugated round, rectangular corrugated or plain rectangular downspout to drain your roof."

Ummm, Nicky? rectangular downspouts don't have a diameter... and then there's this:

"Measure the distance from the end of your gutters to the ground and then an additional three to four feet out from that spot to determine the length of downspout that you need to install."

We assume that's to help divert water from the foundation. We don't think Nicole intended to factor in the width of the eaves (see image), since she never mentioned the word. Lastly, Schmoll's confused about many things, but one of them bothered us most. She says in her introduction that you need to know the area of the roof and "the average amount of rainfall you receive" to size your gutters. That's incorrect: you need to know the expected rainfall intensity to choose the correct size. Schmoll's reference even goes into some detail on intensity, but Nicole either didn't bother to read it or, more likely, didn't understand it. Either way? Dumbass of the Day!

copyright © 2017-2022 scmrak

DD - GUTTERS