If you live someplace where you have expansive soils with high clay content, you are required – by code – to have gutters; it’s not just better, it’s the right thing to do. Because of the high clay content, such soils change size considerably across wet-dry cycles. Those size changes can create voids and can push horizontally and vertically. This can lead to structural failure, which gets to building science’s most fundamental principle: no killing the people. Structural failures are serious, like water leaks times a million, and that’s why this requirement exists in the code. If water in the soil can cause a structural failure, then you are required to keep your roof water away from the soil near your foundation. That makes sense. That’s better.
If your house is built on a well-drained sand pile, then maybe you can skip the gutters. Maybe.
If you have good, sandy soil, and if your house is slab-on-grade construction (no crawlspace, no basement), and you have a large overhang, you can get away with no gutters. The overhang is the thing saving you. Without the overhang, you get too much splash-back against your exterior cladding.
Splash back can really ruin things, like accelerate the decay of stone, peel your paint, rot your siding, and give bugs a great, moist place to live and work. Three feet is about enough for this overhang if you don’t have gutters and seems to keep the splash-back water off the siding, but more is always better. Of course, splash back happens at upper levels also, from flat roofs or roof terraces, so those need overhangs or gutters above them in the same way that eaves above grade do. If you have a basement or crawlspace (and sandy soil), I recommend a wrap-around porch, so, that’s about a 6-foot overhang, minimum.
Building our homes down into the ground, with basements and crawlspaces is a dumb idea. It’s dumb for a variety of reasons, not the least of which is the high cost. Frequently, it’s bedrock-hard down there, it’s cold down there, it’s wet down there, it’s dark down there. It’s dirty underground! Sometimes it’s not just wet, there are actual underground streams. Occasionally, it’s really stinky or otherwise dangerous because of nasty chemicals in the soil – some natural, some man-made. Remember Jed Clampett and The Beverly Hillbillies? And, don’t forget about radon, uranium, or the dry-cleaning shop that operated next door for the past 90 years.
Regardless of the problems involved, since the invention of electric light, the value of basement space has overcome the expense of building it, so we now have all sorts of bad-idea basements in all sorts of places. If you have a crawlspace or a basement, your house is usually better off with gutters.
Some foundation water conditions are worse than others. Like when you build in a swamp or there’s an underground stream or spring below your house. In those conditions, you have to build a foundation that functions somewhat like a concrete boat, not a typical residential foundation. This is not so unusual for large commercial buildings since they have very deep basements that extend deep into very wet conditions, but it’s sort of unusual (and expensive) for residential construction. If those are the conditions you’re building in and you’ve designed the foundation to deal with it, and you’ve designed overhangs to prevent splash-back damage, then you can probably skip the gutters. They just don’t make a difference with regard to the water around your foundation in the same way that more rain on the ocean doesn’t change the effectiveness of a boat hull. You’re already at 100% water, you’re not going to get to 105%. Splash back, at ground level and upper levels, of course, is still an issue that needs to be dealt with.
More typically (99+%), basements are set into soil that is wet but not “under water,” and some amount of drainage or pumping can effectively remove this water and leave the basement dry. In those (typical) conditions, foundations are not waterproof. They are not built like boats; they have holes in the bottom and water will enter even if there is the tiniest amount of hydrostatic pressure. The only thing keeping the water out is an effective drainage system. If the water doesn’t get to the hole, it’s not a leak. If the water gets to the hole but has no force pushing it through, it’s not a leak. Drainage mats, capillary breaks, and drainage systems allow gravity to be the controlling force and allow us to live, happily, with holes in our foundations that never leak.
“Effective” is the key word in that last paragraph. If you have no gutters and you dump your roof water into the ground around your foundation, you may overwhelm your drainage system and then it will no longer be effective. Drainage systems work best when they have no water to remove. Any amount of water greater than zero starts to put the system at risk. How much risk are you willing to live with?
My recommendation: Keep it very low risk, install gutters, drain them away from your house, and keep the soil around and below your basement foundation walls as dry as possible. Do not pipe your downspouts into your footing drains; keep roof water entirely separate from your below-ground drainage system. Do direct or pipe your downspouts away from your foundation and don’t let them spill out onto the ground anywhere within about 6 feet of the foundation wall; farther is better. Do provide a means of preventing sticks and leaves and tennis balls from getting into your downspouts (or, at least filtering them out if they do get in). Do provide a means of easily cleaning out your downspouts if they go underground, maybe like these cool details (above).
In locations where it snows a lot, you rarely see roof gutters.
I thought that was because the locals were just a bunch of mountain Hillbillies who didn’t know any better, or maybe they stole all the aluminum and sold it as scrap so they could make a down payment on their next set of dentures. Then my parents moved to one of those snowy, mountain towns and my brother and his family to another. Then I visited Aspen and Sun Valley. Hmm…Sun Valley…a few Hillbillies, but I realized I needed to recalibrate my thoughts. Now I know it’s because they knew something I didn’t know: Roof gutters in snow country get torn off as huge amounts of snow slide off the roof (somewhat because of some historically poor roof insulation but that’s another story). My take away: Ignorance is reflective – my ignorance seems to become the other party’s when I don’t realize I’m the ignorant one.
There are three solutions to this snow-destroying-the-gutter problem:
- Waterproof your basement like it’s built in a swamp and risk it with no gutters.
- Install the gutter at the eaves but lower it down below the line of the roof pitch. This allows the sliding snow to go past it without tearing it off the eaves. (This only works,by the way, if you have properly air-sealed and insulated your roof and attic assemblies. Otherwise, the snow melts, and the gutter catches that melt water, ices up, and tears off when the ice goes sliding off with the snow.)
- Install the gutter in the ground.
I like in-ground gutters, and they can be used in any non-urban setting, but, just like eaves troughs, they need regular maintenance (that’s at least twice per year), and you can’t plant anything on top of them.
Except for preventing death from structural failure, preventing water in your basement and keeping water off your walls, I really don’t like gutters. Downspouts even less. Gutters at the eaves are a big, high risk (like falling-off-a-ladder-and-dying risk) and maintenance hassle and I really don’t like that. I doubt there’s ever been a gutter, in the history of gutters, that has been properly maintained for its entire service life. Even in-ground gutters require attention. They aren’t like a paint job – every 10 years, then forget about it; every few months, you’ve got to pull the weeds and put the gravel back in place. I prefer big overhangs. If those aren’t part of the design, then, regardless of whether they are at the eaves or in the ground, and regardless of how much hassle the maintenance is, unfortunately, gutters are the required or wise choice, and your house is better off with them.
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