An inch of rain on a 2,000-square-foot roof is about 1,250 gallons of water, and all of it comes out of four or five downspouts within arm’s reach of your foundation. Knoxville averages roughly 50 inches of rain a year, so a typical roof here sheds more than 60,000 gallons annually — delivered, by default, right against the house. Roof water is the single largest water source on your property and the only one you fully control. Controlling it is this service.
Why splash blocks lose in clay
A splash block or a short flip-up extension moves water two or three feet from the wall, then trusts the ground to absorb it. East Tennessee red clay doesn’t absorb it. The water sits, then follows the loosest soil available — which is the backfill zone along your foundation, disturbed when the house was built and never as dense as the undisturbed ground beside it. Water dumped near the wall rides that soft column straight down to the footing. On the crawl-space foundations most Knoxville homes sit on, that means damp air, wet piers, and rot food under the floor; on a basement, it means hydrostatic pressure against the wall.
This is why so many wet-crawl-space calls turn out to be downspout jobs. Before anyone sells you an expensive interior fix, a cheaper question deserves an answer first: where does the roof water go?
Signs the downspouts are your actual problem
The evidence is usually in plain sight. A trench carved into the mulch below a downspout. A stripe of moss or splash-back staining on the foundation. Soil washed onto the sidewalk after every storm. A crawl space or basement corner that’s always damp on the same side of the house a downspout lands on. A driveway that becomes a river because half the roof drains onto it. None of that is subtle once you look — and matching each downspout to the damage below it is the first thing we do on an estimate walk.
What a buried downspout line looks like
We connect each downspout to solid, smooth-wall PVC just below grade: a catch adapter at the downspout, a cleanout or debris filter where it earns its place, then buried pipe with consistent fall carrying water to a discharge point well away from the house. At the end, a pop-up emitter sits flush in the lawn and lifts open under flow — or the pipe daylights on a downslope where the lot provides the grade, which on Knoxville’s hilly terrain, from Bearden out to Farragut, it usually does.
Two build details matter more than everything else. Solid pipe, not perforated: this line’s job is to move water away, not leak it into the soil en route. And smooth-wall, not corrugated: corrugated pipe traps debris on its interior ridges and can’t be jetted clean, which is exactly how most buried downspout lines die. Built right, the line serves for decades, and if it ever does clog, a jetter clears it through the cleanout in minutes.
Where the water goes when there’s no downhill
Not every lot drains to daylight. When there’s no fall to work with, we route downspout lines to a dry well — a buried chamber that swallows the surge from a storm and releases it into the surrounding soil over the following hours. Sizing is the whole game in clay, which gives water back slowly, so we size the well to the actual roof area feeding it instead of guessing.
Downspout lines also tie into larger systems. If we’re already building yard drainage, roof water joins the same discharge network — with one firm rule: downspouts never connect into the perforated pipe of a french drain. Roof water would overwhelm the drain and inject leaf debris into a pipe built to collect clean groundwater. The two systems can share a trench and a discharge point, but they run in separate pipes, always.
What we don’t do
We’re not a gutter company. We don’t clean gutters, install them, or repair them — and if yours are overflowing at the seams because they’re clogged or undersized, fix that first, since no buried line can catch water that never enters the downspout. Our work starts where the downspout ends: getting water from the bottom of the pipe to somewhere it can’t hurt the house.
That focus works in your favor at quote time. We’re not upselling gutter guards or new gutters — we’re pricing pipe, fittings, trenching, and a discharge point that actually works.
Do the whole house once
Downspouts tend to get buried one at a time by whoever’s handy, and the result is four different fixes in four different stages of failure. It’s cheaper per run — and far kinder to the yard — to trench the whole house at once, combine runs where the grade allows, and send everything to one or two well-built discharge points. That’s also when the forgotten downspout gets caught: the one draining half the roof onto the driveway, feeding the sheet of water that ends up at the garage door. Homes with attached garages in Maryville and Farragut produce that call every wet season.
What it costs
A single buried downspout run typically lands between $300 and $800, depending on length, obstacles, and the discharge arrangement. Whole-house projects — four to six downspouts to one or two discharge points — mostly run $1,000 to $4,000. Shallow rock, long discharge runs, and crossings under sidewalks or patios are the usual price movers. Fixed quote after we walk the house; the estimate is free.
Send your roof water somewhere useful
Sixty thousand gallons a year is going to go somewhere — the only question is whether you choose the destination. Call or use the quote form and we’ll trace every downspout, show you where the water goes today, and price the version where it goes away from the house instead. Free estimates throughout Knoxville and the surrounding towns.