Are roof gutters necessary? It depends
Q: IthinkI’vegota good idea. I’m reroofing twoofmy barns with metal roofing. Iwas thinking of extending the roof past thewalls 18 inches so drippingwater falls farther away from the barnwalls. Right nowI’ve got gutters and I’m tired ofthemcloggingupwith leaves and debris. What is the best practicewhenitcomes to gutters ornogutters? Whatabout sizes forboth gutters anddownspouts? Whatwould youdoif you wereme?
A: This conundrum is an excellent example of a tip I’ve shared withmy children. I’ve encouraged them to travel far and wide. When you do this, you discover things you feel are normal are not so normal in other places. I remember being in Toronto years ago thinking itwas strange they didn’t have a separate directional arrowtraffic signal light telling youwhen itwas safe to turn left at an intersection. After all, that’s what I’m used to in theUnited States. Those clever Canadians just had the green light flash to tell you itwas safe to turn. They felt therewas no need for an extra light.
I grewup inCincinnati. The soilmakeup there is a dense, poorly draining clay deposited by a series of four massive continental glaciers that covered the land all theway fromthe North Pole to theMidwest four times in the past 2 million years. But guess what? The soilmakeup inNewEngland, where I nowcall home, is quite sandy and it drainswell. Soil composition is a very important thing to consider when it comes to the question of gutters or no gutters, it turns out.
Here inNewEngland, most houses and barns have no gutters. Not only is the soil conducive to great drainage, but the snow and ice on roofs have a tendency to rip gutters off structures when it slides and tumbles off the roofs. Gutters tend to be less than ideal inNewEngland for those two reasons.
It’s important for you to consider the amount ofwater that comes off a roof. Recently, we had two inches of rainfall at my house in just one day. The footprint ofmy house is 1,625 square feet. Had I harvested all thatwater in a cistern, Iwould have collected 2,025 gallons in that short time. Not everyone can harvestwater because of laws in different states, but that’s a topic for
another time.
Here inNewHampshire, coarse gravel the size ofwalnuts is placed on the soil beneath the drip line of the roof. This is an ingenious method of minimizing the splash of the water against the structures. You don’twant lots ofwater getting the side of your home or barnwet. Gutters and downspouts will collect thiswater and pipe it to another location to minimizewetting.
Gutters and downspouts are a great idea if you have a full basement orwant a dry crawlspace. Can you imagine injecting thousands of gallons into the soil next to your foundation and then HOPINGit doesn’t seep into a basement or crawlspace? This iswhy I always advise peoplewhosuffer
fromwet basements to be sure to pipe roofwater away fromtheir homes to the lowest spot on their building lot.
Typical residential K-style gutters come in two sizes: 5 inch and 6 inch. By far, the 5-inch size ismost popular andworks for most roofs. The downspouts help you size the gutters. Typical downspouts come in two sizes: 2-by-3-inch downspouts fit 5-inch gutters, and 3-by-4-inch downspouts fit 6-inch gutters.
The shape of your house or barn and your fussiness aboutwhere you want downspouts to be on your house or barn drives the decision onwhat to do. Asingle 2-by-3-inch downspout will handle
600 square feet of roof area. Surprisingly, a single 3-by-4-inch downspout will handle 1,200 square feet of roof area.
The downspout should drop into buried undergroundSDR-35 plastic sewer and drainpipe. This pipe will carry thewater far away fromthe house orbarn. If youliveinacity, youmight be required to pipe your roofwater into a local storm-water sewer system or a storm-water holding pond.
Avoid using the plastic or concrete splash blocks at the base of a downspout. These do nothing to get thewater away fromyour foundation. They’re foolish impostors and trick you into thinking that the roof water is being handled correctly.
Great micro-mesh gutter guards can stop debris from getting into gutters. I’ve done gutter guard testing for years and found micro-mesh to be the best system. It’s important for the gutter guards to be installed so their slope matches the slope of the roof above them. Thisway leaves, twigs, bark and other debriswashes offor is blown offthe guards on a windy day.
Myownhome isagreat example of howcomplex your decision might be. I have gutters and downspouts on part ofmy home so the roofwater doesn’t splash up ontomy house where I have decks andmy front porch. At other parts ofmy house, the roofwater drops to the ground and disappears into the coarse gravel.