French Drain Basement: All You Need to Know

A French drain basement is a system that collects water, moisture, and mold that usually builds up in cold and rainy places. It drives the water into a shallow trench, which is connected to a pipe, and then expels it with a sump pump. It does not work on gravity.

It was created by Henry French, who proposed a brainchild to stand up to floods in 1959. A French drain basement is a structure that prevents leaks in areas that are rainy and wet. So, a French drain basement protects homes against basement flooding.

A French drain basement can use pumps or sump pumps to get rid of water and leaks. It uses special pipes installed under the basement floor that collect the rainwater. With that being said, a French drain basement is ideal for reducing hydrostatic pressure, which normally weakens the basement walls and causes trouble in waterproofing systems.

In this article, we’re going into the use of the French drain basement. There are two types of French drainage for basements: interior French drain and exterior French drain. The latter is more suited to control humidity and leaks in gardens. Both actually require little maintenance and are durable.


French drain basement perimeter drain, interior french drain, french drain installation cost
French drain basement

Interior French drain and exterior French drain

As said above, an interior French drain will definitely perform better in basements than its counterpart, the exterior drainage.

If exterior drainage cannot keep a basement dry, an interior French drain can help. A French drain basement consists of a trench in the basement walls and gravel. The trench is in the pipe and has holes that facilitate the water flow. You can connect one or various sinks to this system.

The French drain basement will drive the water underground, more specifically into the trench below the floor. The system has a sump pump that removes excess water safely.

This is the difference between a French outdoor drain and a French drain basement. While an outdoor drainage system does not need anything but gravity, a French drain relies on a sump pump and pipes to get the water out. These pumps have a powerful battery to handle larger amounts of water faster.


French drain basement perimeter drain, interior french drain, french drain installation cost

Do French Drain Basements Work?

French drain basements are effective in solving a number of problems linked to basement water leaks. Excessive accumulation of water can cause numerous types of damage. Moisture can cause irreparable damage to items stored and appliances installed in the basement.

By constructing a French drain basement, the water cannot permeate into the basement walls. When water accumulates, it exerts pressure that can lead the basement walls to collapse and allow leaks. A French drain basement is ideal in places with cold climates and heavy rains. You won’t need to re-build or replace this basement frequently either, as it is low maintenance.

If the water table is high, you may require a perimeter drain. Areas with a high water table are slow to dry, which, in the long run, leads to seepage. A French drain basement can prevent this.

Also, consider getting a French drain basement if your household is near a river or lagoon. Heavy rains can flood basements if you have no basement drainage or have one improperly installed.


French drain basement perimeter drain, interior french drain, french drain installation cost
A sump pump with some water


Installing a French drain is a large project and should only be tackled by those with extensive construction or maintenance experience. Before you put a French drain basement, you should already have a basin, sump pump, and outside drain so that the water collected in the basement can flow out.

A French drain basement should be approximately 8 inches to 2 feet deep. In systems like underground living spaces and containment bases, a French drain can be deeper.

The drain should run about 1 foot (or 30 cm) from the basement to the exterior wall. A French drain basement must be in a place with a higher humidity level. The system ends with a basin that collects the water that comes from the trench and pipe. The sump pump will expel all this water to the outside.


French drain basement perimeter drain, interior french drain, french drain installation cost
A basement with no drainage system


Is a French drain basement durable?

The water will run through the gravel for the first 10 to 20 years before the plate clogs the gravel completely and reaches the pipe, which has holes facing up and cleaning outlets on each wall. With proper maintenance, a French drain basement will last a lifetime.


French drain basement perimeter drain, interior french drain, french drain installation cost
Basement flood


A French drain installation cost is not low. So, whenever you’re planning to install a French drain basement, prepare to spend at least $2000 to $6000. The average price is around $4500, but if you decide to build a simple French drain basement, you might spend $1100 or less.

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