How Deep Should a French Drain be Installed

Homes or properties that have basements will be vulnerable to water pooling. Groundwater can seep into the foundations, rainwater or water runoff from any nearby source can also inundate or flood the basement. Properties in low lying areas are particularly vulnerable since the natural slope of the area owing to the topography will facilitate water pouring in from one or more sides and that will lead to standing water in and around a property. Usually, a property has a few problem areas. If the entire property is inundated then the entire drainage is faulty. For specific areas that are at risk of being flooded or inundated to varying extents, a French drain can be the perfect remedy.

French drain is a rather simple solution. It is not an expensive remedy, it doesn’t require any alteration to your home and it can be installed in and around most types of properties. You do have to invest substantial time and effort though. A French drain is simply an outlet for water to be pumped or drawn out from a problem area to somewhere beyond the premises. A French drain can lead to the roadside sewer lines or city drains. It can lead to nearby low lying areas or just outside the premise of a property. A French drain doesn’t have a pump or any such mechanism. It can have one but the traditional design simply uses gravity and a channel to draw water out of an area that is prone to flooding or standing water.

Quintessential Requisites for a French Drain

Installing a French drain will require several tools and materials, including exterior screws, pressure-treated pine, lag bolts, galvanized fender washers, pine planks, drills, measuring tape, spray paint for landscape marking, shovel, cement, a tub to mix the cement, pencil, saw, wrench, torpedo level, hammer, speed square, screw swing, bushing, sanding pads, orbital sander, paint, roller handle, paint pan and painter’s tape, heavy-duty nylon rope and utility knife. In addition to the drainpipes, you would need gravel and filter fabric.

The Depth of a French Drain

There are three significant attributes of a French drain. It must be impregnable and reliable so it can continue to function as it should. The drain must not interfere with any existing structure in and around the property. It should be completely free from internal or external influence and should not influence any fixture such as cable or pipe anywhere. The third element is the most important. The drain must have a slope or gradient. Unless there is a significant slope or gradient, water wouldn’t flow out. This gradient can be provided naturally if the property has low lying areas around it. The same slope will have to be created if a property is in a low lying place and the grounds nearby are elevated. The solution is a trench that is deep enough to allow gravity to work its magic.

Before you dig the trench, you should measure the elevation of the ground and study if there is a natural slope leading outward and downward from the property. If this is the case then the French drain can be six inches wide and you can aim for a depth of a foot or a foot and a half. You may aim for a depth of two feet if you want the drain to be more reliable. The deeper a drain, the more resistant it is to damage caused by weather and external factors. If you have a scenario where the house is pretty much in a low lying area then you have to dig a deeper trench. You must go beyond the two feet and perhaps you have to go five feet deep depending on where you are leading the water to and whether or not the drain has a consistent downward slope away from the house or the problem area of the property.

Depth of 2 Feet to 5 Feet

To sum it up, you can easily do with a foot of depth if your property is relatively on high ground or even at leveled ground. You should go for two feet if the basement is lower into the ground than usual or if you have two or larger levels underground. You should go for three feet to five feet if you don’t find the right gradient. It should be remembered that water doesn’t flow out smoothly and completely unless there is a significant slope at the problem area. You can go for a gradual slope once the drain leads away from the property. Right at the property or around you would need a significant slope. This is tricky because you have to keep going deeper as you move away. Any reversal of the slope or gradient will lead to water pooling inside the drainpipe, which is not what you want.

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