Interior vs Exterior French Drain for an Edwardsville, IL Home

Direct answer: Exterior drains intercept water before it reaches the wall — structurally the better outcome, but the most disruptive and expensive to install because it means excavating to the footing. Interior drains manage water after it has already entered, cut into the slab and routed to a sump. They cost less, install faster, and don't touch your landscaping — the trade-off is that they treat the symptom, not the source.

Side-by-side comparison

Factor	Interior drain	Exterior drain
Cost per linear foot	$60 – $110	$95 – $180
Install time	3 – 5 days	5 – 10 days
Landscaping impact	None	Full excavation and restoration
Requires sump pump	Yes	Sometimes (gravity discharge possible)
Stops water before it enters wall	No	Yes
Livable during install	Yes, basement unusable temporarily	Yes, yard access limited

Edwardsville and Madison County averages. Actual cost depends on perimeter length, soil, and access.

Can you live in the house during installation — either way

For both methods, yes. Interior work means jackhammering a channel along the basement wall, which is loud and dusty for the duration and puts the basement itself out of use, but water, power, and the rest of the house keep functioning normally. Exterior work is noisier and messier around the perimeter of the house — expect equipment on the lawn and limited yard access — but it never touches the interior. Neither method requires you to leave the house, though families with a finished basement in active use during interior work sometimes choose to relocate activities upstairs for the week.

How to decide which one you actually need

Start with what the water is doing, not what the product is called. If the basement is dry for long stretches and takes on water within hours of a heavy storm, that's usually surface water — a grading or downspout problem — and neither drain type is the first fix; correcting the surface issue is. If water arrives on a schedule tied to a rising water table rather than rainfall, that's hydrostatic pressure, and a drain is the right category of fix.

Between the two, budget and disruption tolerance usually decide it. An interior drain is the far more common choice in this area because it's less expensive and doesn't touch the yard — most homeowners accept "manage the water after it arrives" as a reasonable trade for a lower bill and a faster job. Exterior is worth the extra cost when landscaping is already being redone, when the wall shows active deterioration from prolonged pressure, or when a homeowner wants the water stopped before it's inside at all.

Interior vs exterior French drain: questions

What is the difference between an interior and exterior French drain?

An exterior French drain sits outside the foundation at the footing and intercepts water before it reaches the wall. An interior French drain is cut into the basement slab along the wall and collects water that has already entered, routing it to a sump pump. Exterior is structurally preferable; interior is far less disruptive and less expensive.

Can you live in the house while an interior French drain is installed?

Yes. Interior drain installation is loud and dusty for the days it takes, and the basement is unusable during work, but the rest of the house — kitchen, bedrooms, bathrooms, water and power — stays functional throughout.

Which is cheaper, interior or exterior French drain?

Interior perimeter drains typically run $60 to $110 per linear foot. Exterior footing drains run $95 to $180 per linear foot because of the excavation depth and landscape restoration. On a typical basement perimeter, that's often a several-thousand-dollar gap.

What we put in writing before anyone commits

The diagnosis — surface water vs. hydrostatic pressure — comes before the product recommendation, in writing.
Both options quoted side by side when both are structurally viable, with the trade-off stated plainly.
Expected disruption (basement downtime, yard access) disclosed before work starts, not discovered mid-job.
Fixed price before ground is broken; surprises don't move the number without a written change order.