French drain INSTALLATION COST

Downspout extensions compared

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Choose the extension by the route water can take, the space people use and the access you need for maintenance.

US house and yard cutaway showing the drainage systems outside the house.

Which downspout extension should I use?

Choose the extension by the route water can take, the space people use and the access you need for maintenance.

Rigid surface extension

A rigid extension makes its route and discharge easy to inspect. It needs room on the ground and can interfere with mowing or walking. Check that the receiving surface carries water away instead of creating a new puddle.

Secure connections and inspect after lawn work or storms.

Flexible or roll-out extension

A flexible extension can work around small obstacles but needs a stable route that does not kink or hold water. Roll-out products reduce the visible footprint when dry, but their operation and durability depend on the specific product. Evaluate the actual outlet and maintenance needs rather than selecting by concealed length alone.

Solid underground pipe

A buried solid run can cross an open lawn without a permanent surface obstacle. Installation requires utility coordination, verified elevations and access for cleaning. Pavement crossings and a new outlet add work.

Confirm where the pipe ends and how the contractor will make that point visible and serviceable.

Compare the included work

The installed allowance below concerns downspout drainage work, not the retail price of a short extension. Ask separate questions about connectors, run length, excavation, discharge and restoration. If a surface extension solves the roof-water problem, a buried system may not be necessary.

Cutaway of a yard French drain trench beside a brick ranch house: fabric-lined trench, gravel and a black perforated pipe under the lawn.
A yard drain in cross-section; outlet suitability needs an on-site check.

Nonwoven fabric keeps soil out of the gravel so the drain doesn't clog.

Washed gravel around the pipe lets water reach it from every side.

Water rises into the holes and runs along the pipe, which slopes toward the outlet.
Questions to ask before work starts
Which option is best for a walkway?
Avoid creating a trip hazard or sending discharge across the walking surface. Ask for a route that handles both water and pedestrian use.
How far should it extend?
The receiving grade and local requirements control the answer. PNNL’s program guidance is useful context, but a fixed distance alone does not prove a route will drain.
Sources
Cutaway of a yard French drain trench beside a brick ranch house: fabric-lined trench, gravel and a black perforated pipe under the lawn.

French drain cost

Per-foot prices, worked examples and what changes the total.

US house and yard cut away to show a French drain, downspout line, dry well, catch basin and driveway channel drain.

French drain installation, step by step

What a pro does, from the site check to lawn repair.

Two-story US house with a gravel French drain trench curving through a wet lawn.

French drain for a soggy yard

When a yard drain fixes standing water, and when it won't.