When the roof shingles were removed, we hoped to finally solve the last big architectural mystery of Comstock House - but what we found was completely unexpected, and has led to other questions we still can't answer for certain.

The puzzle concerned the rain gutter system in the front of the house. We knew that there were downspouts inside all three of the columns, which were (presumably) attached to the back of the original gutters, and the aesthetic goal probably was to avoid big ol' metal downspouts from spoiling the look of the otherwise all wood-and-window house. Nice, but drawbacks include the risk that heavy rains could overwhelm such an enclosed system and cause leaks inside the house (the architectural history of this topic was discussed in an earlier essay). However that system was designed, we believed it apparently wasn't very successful. Between the earliest known photo (probably 1905, a few months after construction) and the 1908/1909 postcard, a rainstop board appeared above the actual gutter, likely intended to slow the torrent of rain as it shoots down our steep-pitched roof. Even that didn't perform very well; during the heavy rains of 2009-2010, every downpour turned the front of the house into a waterfall.

Until the shingles were ripped off, it was unknown what architect Brainerd Jones had engineered, or whether he had left that problem to contractors Williamson & McKenzie. Aside from the gutter profile shown above, there was nothing specified in the blueprints or in the written specifications. Thus we were completely surprised to find ourselves staring at not one, but two pipes emerging from each downspout. It was the oddest thing that any of us had ever seen.

Each pipe was 1½ inches and had bent-up lead flashing, which suggested that both pipes once emerged from the roof. The lower one was clearly once attached to the gutter; but what purpose served the upper pipe?

One theory was that the roof originally had oversized dutch gutters (also called box gutters, yankee gutters or integral gutters). These were sometimes used in Victorian-era America and were part of the house structure, built between the end of the roof and the flat board fascia that is visible from the ground (good diagram here, if trouble visualizing this). In this theory, our pipes acted as dual drop outlets (or maybe, a drop outlet with an emergency overflow drop outlet). Logical, yes, likely, no. The monster-sized fascia covering this design would have to be at least 8" high, and nothing like that is seen on the early house portraits or in the blueprints.

Theory #2: When the original gutter system failed, they improvised a second gutter above it to help intercept the cascade, and what we thought was a rainstop was actually a trough gutter (AKA stop gutter or Yankee Barn gutter). It's an interesting possibility, but couldn't be true; the two pipes were made and installed when the house was being constructed.

So to paraphrase Sherlock, once you've eliminated the impossible, whatever remains - however unusual - must be the truth, and this is it: Each downspout had its own private air vent.

LEFT: The northeast downspout and vent, as seen from the front
MIDDLE: The same downspout and vent, seen from behind
RIGHT: The center downspout, still sealed with a lead plug

Technically these are "back vents," and Brainerd Jones might have suggested that the contractor build these as part of his terse directions found on page 21 of the specs: "Vents from other fixtures, back vent where practical..." But the two big questions are A) was this design unique? and B) did it even work?

Researching this proved a great challenge; understanding turn-of-the-century plumbing is sometimes like trying to solve a crossword puzzle written in Ye Olde English. Terminology wasn't always the same as today (and sometimes descriptors meant the complete opposite), and there were a jumble of terms to describe the same thing. Quiz: Around 1900, what did they call the pipes that carried rain from the gutters? Possibilities include "downspouts," "conductors," and "leaders," sometimes mixed with a prefix of "roof" or "rain" or "water". When I discovered hyphens were sometimes used ("rain-water down-spout") and using that combination returned still more unique results in a Google book search, my brain popped a tiny aneurysm.

Victorians had the notion that a downspout could have multiple purposes. They could double as air vents for the sewer system, or rainwater could be diverted into regular waste pipes in the house, with the hope that a big storm would flush away grease and other clogs. Of course, if the downspout itself was clogged with leaves or snow, the entire venting system failed; sinks didn't drain and toilets didn't flush. That practice ended and you'll find many building codes from c. 1890 onwards adamant that "Rain water leaders must not be used as soil, waste, or vent-pipes." The emerging uniform building code also included two other points of interest to our mystery. There was a rule for downspouts concealed inside buildings, specifying that the downwpout be made of sturdy material and absolutely watertight with the gutter - a no-brainer, but it shows inner-wall downspouts were considered an acceptable building practice. And at least from 1915 on, the Uniform building code required vents for each plumbing fixture, but specifically stated no vents were necessary on downspouts. That might have been included for completeness' sake, or it might suggest that some builders were venting downspouts, and the practice had come to be considered superfluous.

But after all that research, I could find only a single mention of an actual vented downspout. It appeared in a 1889 journal published by MIT, then reprinted the same year in the widely-read trade magazine, "American Architect and Architecture" (Volume 26). It described an ancedote told by New York's Chief Inspector of Plumbing, where a basement was flooded because the downspouts couldn't keep up with high water volume from a heavy rain. The problem was solved by adding an air vent to the downspout. Now the idea makes sense; vents allowed water to shoot down those pipes like a firehose.

So finally we're at the big question: Did Brainerd Jones' system work?

Engineering reference books in that era provided tables showing every calculation a builder would probably need, including the proper diameter of gutter and downspouts calculated for the size of the roof. The rule at this time was one square inch of downspout for every 250 square feet of roof area. With each watershed of the Comstock House roof covering roughly 2,000 square feet, the house needed eight square inches of downspout per side. The vented system here came up short. Each 1½ inch diameter pipe provided about 1.75 square inches, so all three downspouts together offered a combined 5.3 inches.

The other part of the calculation was the size of the gutter itself, and here either/or the architect or builder stumbled. The charts specified a gutter of eight inches wide; the redwood gutters used on Comstock House were the standard five-inch width, which we verified after finding a discarded cut in a crawl space, seen at right.

But the undersized gutter wasn't the worst problem; we discovered that the middle downspout was never connected. The pipe was still sealed with a lead plug that would have been used during a plumber's smoke test for leaks. Considering the incredible speed of the construction of Comstock House, it's likely that the construction foreman didn't notice that the roofers had shingled over the plumber's mistake. The result was that the front downspouts could not have handled a watershed for a roof less than half this size.

Conclusion: The original rainwater system for Comstock House never worked. The gutters were too small, they needed an additional downspout, and one of the downspouts they had was permanently plugged. The rainstop was installed within a few years, but that didn't solve the problem either. Finally the entire system was abandoned; the redwood gutters were ripped out and replaced with a standard "ogee" five-inch sheet metal gutter, with three downspouts destroying Brainerd Jones' look. And despite all that, the gutters still couldn't handle the volume of water in even a moderately strong rain.

Hopefully our new system, which is over-engineered according to the period specs, will prove more robust. We'll see.


Interesting and informative sharing thanks.

October 22, 2013 at 5:23 AM  

Hello. It's nice to see our house, The Reeve-Townsend house by Greene & Greene, included in your fascinating discussion.

To clarify, the photo you show without the gutters and downspouts was during the restoration. Now, the original placements and design, and many of the original pieces are back place on the house, restoring the original gutters and downspouts.

Great article! Thank you!

October 25, 2013 at 6:59 PM  

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