Crawl Space French Drain Design

French drains, also known as filter drains, are made up of shallow pits that are stuffed with gravel. The gravel fill has a significant proportion of voids, which are subsequently filled with precipitation. It is possible for this rainfall to soak through the gravel layers and make its way to a perforated drain pipe that has been installed at the bottom of the trench.

Does a French drain require an outlet of some kind?

In an ideal scenario, the french drain will terminate to an above-ground exit on the side of a hill or at least a downwards slope. This will allow the water that was contained within the drain to escape and get to the location where the property's normal surface runoff is directed after leaving the property.

How steep should the slope be on a French drain?

A slope is required for the effective operation of a French drain. The angle of the slope ought to be such that it declines at a rate of 1 percent. This rate results in a drop of one foot for every one hundred feet of French drain that is installed. Alternately, the terrain on your land can naturally slope in a steeper direction, which is just OK.

Is covering a French drain with soil even possible?

You shouldn't put dirt on top of a French drain's pipe because it has holes all over the pipe that allow it to absorb water. These holes allow the drain to function properly. By installing soil, you will obstruct both the pipe and the holes, which will render the pipe ineffective.

In order to properly construct a French drain, what size gravel should I use?

For optimal drainage, choose natural round rock that is 1 1/2 inches in diameter. The best rock to use is washed rock. Steer clear of little pea gravel since the crevices in between the stones are narrower, which reduces flow rates. Steer clear of Crushed Rock (minus), since it tends to pack down and contains "fines" that might choke pipe inlets.

In a crawl space, what does it mean to have a French drain?

The crawl space is equipped with French drains that lead to sump pumps in order to remove any standing water. They can also be installed to divert water away from the foundation wall and away from the building. The installation of waterproofing drains is essential in the event that heavy rains cause water to seep into your crawl area.