Grading and Downspouts: Keeping Water Away From the House

The Cedar Park backyard I walked last August looked fine for a drought — cracked clay, dead St. Augustine, nothing dramatic. Then the homeowner pulled up phone video from the previous May: a sheet of water sliding off the roof, hitting the ground three feet from the foundation, and pooling against the slab like a moat. That’s the whole problem with grading and downspouts on Central Texas clay. It hides for months, then does its damage in a single storm.

I’ve spent years designing and repairing yards around Cedar Park and the wider Austin metro, and water management is the first thing I check on a property, not the last. It’s the invisible skeleton every good yard is built on. Here’s the checklist I actually walk, in the order I actually do it.

Reading the grade before I touch a shovel

Before touching a shovel, I map where the water goes. The rule of thumb: the ground should fall away from the house at least six inches over the first ten feet — roughly a two percent slope. Walk the perimeter after rain, or run a hose along the foundation, and mark every spot where water sits or runs back toward the slab.

• Look for mulch or soil that has crept above the slab line and now traps water against it.
• Check for that telltale trench under each roof valley where runoff has been hammering the ground.
• Note any patio, walkway, or bed that pitches back toward the house instead of away from it.

Why Cedar Park clay punishes bad grading

On expansive clay like this, a bad grade matters more than it would almost anywhere else. The soil swells when wet and shrinks when dry, and a foundation that’s soaked on one side while bone-dry on the other moves unevenly. That differential movement is what cracks slabs — not the drought by itself, and not one storm by itself, but the mismatch between the two happening a few feet apart.

Fixing the grade first

Regrading is unglamorous, and it’s the highest-return dollar you’ll spend outside the house. To rebuild positive slope I bring in sandy loam fill — never pure topsoil, which holds water against the wall — and feather it out to hit that six-inches-in-ten-feet target.

Where the lot is flat and there’s nowhere for water to sheet off, I add a swale — a shallow shaped channel that carries runoff to the street or a rain garden. A planted swale reads as part of the design, not a drainage scar, which is the whole point of hiring someone who thinks about how a yard looks and how it works at the same time.

The downspout mistakes I see on almost every job

A perfect grade fails if your downspouts dump straight at the foundation. This is the cheapest, fastest win most homeowners have sitting right in front of them:

1. Extend every downspout at least four to six feet from the house, farther on the uphill side of a sloped lot.
2. Discharge onto a splash block or, better, into buried solid PVC that daylights out in the yard.
3. Never tie downspouts into perforated pipe near the slab — that waters the foundation on purpose.
4. Aim discharge points where the ground already slopes away, not into a low spot.

For the reasoning behind moving all that roof water away from the house, the EPA’s overview of downspout disconnection and managing roof runoff is worth a read.

When grading alone won’t cut it

Some Hill Country lots are too tight or too steep to solve with slope alone. That’s when I bring in a French drain — a gravel-and-perforated-pipe trench that intercepts subsurface water and routes it away. On sloped front yards I’ll often pair the drain with a low retaining wall so the whole assembly earns its keep visually, too. If your water problem lives right at the base of the house rather than out in the yard, the deeper approaches covered in basement waterproofing from the outside in pick up where surface grading leaves off.

The order never changes: grade, then downspouts, then subsurface drains — only if the first two don’t finish the job. Skip that order and you’ll pay for drainage you didn’t need.

What I’ve actually charged for these fixes

The sand and lime and gravel in any of this are cheap. What you’re paying for is someone reading the site correctly before the shovel ever comes out — because the wrong fix, done well, still doesn’t solve the problem.

Questions I get about foundations and drainage

How much slope do I need away from my foundation? Aim for six inches of fall over the first ten feet, about a two percent grade. That carries roof and surface water away before it can soak the soil next to the slab, which on Central Texas clay is what drives uneven foundation movement.

How far should downspouts extend from the house? At least four to six feet, farther on the uphill side of a sloped lot. Splash blocks are the minimum; buried solid pipe that daylights out in the yard is better, since it moves water past the whole foundation zone instead of just past the wall.

Should I regrade or go straight to a French drain? Start with grading and downspout extensions — that solves most problems for a few hundred to a few thousand dollars in the Cedar Park and greater Austin area. Add a French drain, typically $1,500–$4,000, only when the lot is too flat or too steep to shed water by slope alone.

Do older homes need different drainage work than new builds? Often, yes. A lot that’s had decades of additions, patios, and mulch beds built up around it has usually lost whatever grade it started with, one small change at a time. On those properties I spend more time reading the site — where past owners cut into the slope, where a patio was poured flat instead of pitched — before I touch the downspouts at all.