Why water at the wall ends up in the basement
The water off your roof ends up wherever the downspouts drop it. Each one carries the runoff from a big section of roof to one spot of ground, which is why where it lands matters so much.
The soil right against your foundation was dug out when the house was built and backfilled afterward. It's looser than the undisturbed ground around it, so water soaks in fast and runs straight down along the wall. Once that soil is saturated, water pushes in wherever it can: cracks in the wall, the joint where the wall meets the floor slab, window wells, and gaps around pipes.
Water dumped at the wall is the most common cause of a wet basement or crawlspace. Clean, properly sized gutters catch the water, and the downspouts finish the job by putting it somewhere it won't run back to the house.
Four feet is only the start
Every downspout should discharge at least four feet from the foundation. Treat four feet as the starting point, because plenty of lots in the north metro need more.
Go farther on clay soil. A lot of the Front Range sits on clay, which takes water in slowly and holds it, so runoff lingers near the house instead of soaking away. Some clay also swells when it's wet and shrinks as it dries, and that movement is hard on foundations and slabs. On a lot with swelling clay, carry the water well past four feet.
A negative grade calls for more distance too. If the ground slopes toward the house, water discharged four feet out can run right back to the wall. Backfill settles over the years, so a yard that drained fine when the house was new can end up with a low spot along the foundation. In that case the grade needs correcting, which is landscaping work, and the downspout should still discharge well past the low spot.
Extensions, splash blocks, and buried lines
There are a few common ways to get water out to where it belongs. Each has its place, and the right choice depends on the lot, the soil, and what's in the way.
- Downspout extensions: a length of downspout or a hinged extension attached at the bottom elbow. They're simple and easy to adjust, but they get kicked loose, crushed by mowers, or flipped up and forgotten.
- Splash blocks: a concrete or plastic block under the outlet that slows the water and points it away from the wall. They work where an extension would be in the way, but a splash block alone often isn't long enough to move water four feet out, and it can settle until it tilts back toward the house.
- Buried lines: solid pipe connected to the downspout and run underground to a spot well away from the house, often ending in a pop-up emitter. They stay clear of mowers and foot traffic, but they need steady slope to drain, and debris that gets past the gutter can clog them.
Planning for a Colorado winter
Any buried line that holds standing water can freeze, so it should run downhill the whole way and empty at the surface. A pop-up emitter holds water in its riser, so in a Colorado winter an open outlet on a downhill slope is the safer ending. Never tie a downspout into a perforated foundation drain. That pipe is there to carry water away from the footing, and filling it with roof water does the opposite.
Think about where the water goes once it's out of the downspout. In a Front Range winter, meltwater running across a sidewalk or driveway freezes into a sheet of ice overnight, so aim discharge away from paths you walk on. Keep it out of window wells, off a patio that tilts toward the house, and off your neighbor's yard.
Before the first freeze, check that every extension is attached and still carries water at least four feet from the foundation. After a heavy snow, watch where the melt goes for the first day or two.
How to check your own downspouts
The best time to look is during a hard rain or a fast melt. Walk around the house and follow each downspout to where its water ends up. These are the problems to look for:
- Water pooling within a few feet of the wall, or running back toward it
- A washed-out hole or bare patch at the end of an extension
- Extensions that are missing, disconnected, or pointed the wrong way
- Damp spots or white, chalky stains on a basement wall in line with a downspout
- Water collecting in a window well after a storm
Where the new downspouts go
Ethan looks at where each downspout discharges today during the free on-site estimate, which is the starting point for placing the downspouts on new gutters.
More articles
- 5-Inch vs. 6-Inch Gutters: Which Size Your Roof NeedsTwo houses with the same footprint can need different gutters, because size comes down to the roof area, pitch, and valleys feeding each run and how fast its downspouts drain.
- Seamless vs. Sectional Gutters: Why the Joints MatterJoints are where gutters usually leak. Sectional gutters have a joint wherever two pieces meet, while a seamless system keeps them to the corners, end caps, and downspout outlets.