A French drain is mostly labour and stone. Understanding where those go tells you why one quote is double another, and which one is actually building the drain properly.
Depth and length
Depth is set by what the drain has to intercept and by maintaining continuous fall to the outlet. Deeper means more excavation, more spoil to remove and more stone to backfill.
Length is set by the wet area plus the run to the outlet. On flat lots the outlet run is often longer than the collection section.
The trench must slope consistently. Achieving that on a nearly flat yard is what drives depth up at the outlet end.
Materials that should not be cut
Washed stone, not screenings or fill. Void space is the working part of the drain.
Rigid perforated pipe rather than thin corrugated pipe where it matters, and correctly oriented perforations.
Geotextile wrapping the stone fully, not laid only on the bottom. This is the item most often skipped and the one that decides whether the drain still works in ten years.
A proper outlet: daylight, pop-up emitter or approved connection, with an animal guard where appropriate.
Site factors
Machine access versus hand digging — the single largest multiplier on labour.
Clay, rock and saturated ground slow everything.
Crossings under walks, drives and patios need boring or cutting and reinstatement.
Tree roots, irrigation lines and buried utilities along the route add hand work.
Restoration and comparison
Topsoil, sod or seed, and resetting anything lifted are part of the job. Get them in the scope.
Cleanouts at the ends and at direction changes cost little and make future maintenance possible.
Southern Style Turf & Design installs French drains, catch basins and surface drainage across Lake Norman with the pipe, stone, fabric and outlet written into the estimate.
Frequently asked questions
Why is one French drain quote so much cheaper?
Usually shallower trenching, no geotextile, cheaper pipe, or no restoration included. Compare specifications line by line.
Do I always need a French drain?
No. Roof water redirection and regrading solve many problems for less. A French drain is for water in the soil.
How long does installation take?
Most residential drains are a matter of days, depending on length, access and restoration.
Want this looked at on your property?
We give free, no-pressure on-site estimates across Denver, Mooresville, Cornelius, Davidson, Huntersville and Troutman.
