Roof water at the foundation is a drainage problem of its own.

O’Fallon Quality Drainage treats downspout drainage as its own O’Fallon clay problem, separate from yard seepage. Roof water is concentrated and sudden; a splash block often stops after a few feet. Read this with pop-up emitter installation, French drain installation, and the outlet note.

Roof area, storm volume, and clay splash-block failure

A roof square sheds a large volume in a short storm

A roof square sheds a large volume in a short storm. On clay backfill, a splash block often moves that volume a few feet and stops. The wet ring around a foundation after every rain is a downspout diagnosis until proven otherwise.

Estimate roof contribution from plan area, not from a guess about ‘a lot of water.’ A provider can still measure leaders on site. The planning point is that roof water is concentrated and sudden, while yard seepage is often slower and wider.

Start the field notes at each leader. Record whether the gutter overflows, whether a leader is disconnected, where the splash lands, and whether that point is above or below the surrounding lawn. A wet foundation corner can have several sources, so do not assume one extension explains every wet spot.

Underground laterals versus tying into a French drain

Debris that does not belong in a sock

Leaves and granules travel down leaders. A catch at the leader or a cleanout on the lateral protects the buried run.

A dedicated downspout lateral can run to a pop-up or daylight without mixing roof debris into a perforated collector. Tying leaders into a French drain can work when the collector is sized and filtered for that surge, and when the outlet can take both sources. Mixing them without a cleanout is how a sock fills with shingle grit.

The proposal should say whether each leader remains separate, joins another solid line, or enters a collector after a designed connection. That distinction matters later when a single downspout backs up. A cleanout and a visible release give the next provider a place to test instead of guessing under sod.

Daylighting, pop-ups, and neighbor-lot risk

Daylight is honest when the pipe can emerge on the same lot at a lower elevation without sending a jet onto a sidewalk or neighbor

Daylight is honest when the pipe can emerge on the same lot at a lower elevation without sending a jet onto a sidewalk or neighbor. A pop-up on high ground can work if it actually opens and if ice does not lock it shut all winter. A pop-up in the same bowl the water came from is theater.

Mark the proposed release on a wide photo before a trench is proposed. The useful question is not whether a pop-up is attractive, but whether the finished lawn has fall away from it during the storm. If the answer depends on sending water across a property line or toward a public inlet, pause for a parcel-specific city review.

Frozen, crushed, or back-pitched downspout lines

Shallow laterals under drives crush

Shallow laterals under drives crush. Lines without pitch hold water and freeze. Flexible cheap tubing kinks behind shrubs. A repair file should say whether the failure is crush, freeze, kink, or a missing outlet, then choose open-cut or a limited replacement. See drainage pipe repair.

Look for symptoms before choosing a repair: a leader that spills at the elbow, a pop-up that never opens, water appearing at a joint, or a wet strip only after a freeze. Those observations identify where to expose the run. Replacing the visible first few feet without confirming the outlet can leave the same water trapped farther downhill.

Cleanout placement on a downspout run

Place cleanouts near the leader turn and before a long bury under pavement

Place cleanouts near the leader turn and before a long bury under pavement. Caps should be findable after sod grows. If nobody can find the cleanout in year two, it does not exist for maintenance purposes.

A cleanout should be positioned where a hose or camera can follow the actual direction of flow. Do not hide it beneath loose stone, a planter, or a gate that must be dismantled. The closeout sketch should identify the leader, the turn, the cleanout, and the outlet so future maintenance does not rely on memory.

Cost of extending roof water away from the foundation

National French drain ranges do not price a simple leader extension

National French drain ranges do not price a simple leader extension. Ask for a separate line item for laterals, fittings, pop-ups, and restoration. Combining them into one mystery linear-foot number hides whether roof water was ever addressed.

Inspection after the first heavy storm

Watch each leader during rain

Watch each leader during rain. Water should leave the wall and appear at the planned release. If a pop-up stays shut, or if the old wet ring remains, the lateral is not finished. Send that observation with photos through contact.

Use the same camera angle before and after work. Photograph the wall, the leader connection, and the release while water is moving. If the outlet is dry while the leader overflows, or if water returns to the wall, record that sequence rather than calling the system successful from a sunny-day visit.

Keep the observations leader-specific. One functioning release does not prove that every downspout on the building has a usable path. The final packet should name each addressed leader, its lateral or surface route, its outlet, and any remaining roof-water source that was intentionally left outside the scope.

If a leader is intentionally left above ground or disconnected from the proposed route, say so on the sketch. That prevents a later wet corner from being treated as an unexplained failure of a buried line that never served that leader.

Mark private utilities and use Missouri 811 before burying a new lateral. City review questions go to O’Fallon Engineering when the release involves a public system.