7 reasons to specify hand excavated french drains
A question often asked is: why are french drains important? In this article I will touch on some of the most important reasons why french drain installation should be a top priority for the health of your home and some specifics with respect to the engineering and materials used in french drain installation.
1. French drains should be further defined by using the words “hand excavated french drains”, rather than just french drains. The difference is worth the effort to understand. A hand excavated french drain has more groundwater removal ability during hard rains than any other type of french drain. The materials in the french drain and the engineering that determines the slope and the way the french drain is vented also sets it apart from other french drains. Accept no substitute, always specify hand excavated french drains for long lasting quality and optimal performance.
2. French drains, specifically hand excavated french drains, are aquaducts that collect and vent huge amounts of groundwater when they are properly installed and plumbed. Hand excavated french drains remove groundwater from the foundation areas of the home. The groundwater will likely cause leaking into basements and crawlspaces if not vented from the foundation area. The leaking into lower levels causes foundation spot footings to sink, post and beam structures to sink and dryrot, and basement walls and floors to crumble and deteriorate.
3. French drains are usually installed approximately 12″ wide, and contain a perforated pipe for the groundwater overflow, although most of the groundwater runs on the bottom of the french drain. The french drain also contains a solid pipe usually that connects the rain drain discharges at the side of the home where the downspouts vent into. Both pipes are placed on the bottom of the hand excavated french drain to vent each in its own pipe. The groundwater is vented with the perforated pipe, which acts as an overflow pipe during high rain water. The solid pipe runs the roof water from the gutters into the rain drain discharges, and finally down the solid pipe to a drywell, daylighted vent, sump well or infiltrator system.
4. Hand excavated french drains have straight sides and a flat bottom with no debris. Hand excavated french drains are much more difficult to engineer and excavate, but last longer and perform better because debris does not slump to the bottom of the drains plugging them in time. The river rock holds the sides straight and makes more air in the french drain which allows the french drain to vent more rain water quicker, and the flat bottom speeds the groundwater removal.
5. Hand excavated french drains further distance themselves from other types of machine installed french drains because of the careful way they are excavated, which allows the drainage contractor to avoid busting up irrigation systems, gas lines, electric conduits, telecommunications wires and cable lines for computers and tv. A utility locate is always advised prior to any excavation. Irrigation lines, old rain drains, and french drains are never marked with a utility locate. If you use a machine, your home irrigation system will be trashed. Besides, a ditch witch does not have eyes that can ascertain and create a grade of 2″ per 10 lineal feet on a flat surface in areas that are flat themselves.
6. Hand excavated french drains are attractive to look at when a uniform, clean cut line is formed by the exposed river rock along the 12″ wide french drain. French drains with exposed river rock blend into garden areas and other landscaping features. Even exposed rock drywells look nice with a bird bath set on top of a 4 foot in diameter circle of river rock. Many professional gardens use this opportunity to combine form and function.
7. Hand excavated french drains can be installed in lawn areas in wet low grade or flat areas. While these types of hand excavated french drain groundwater removal systems do not work as effectively or as fast as the ones with exposed river rock on the surface, they never the less most often offer the only alternative to getting rid of soggy marshy areas. The same system on a larger scale is used in agriculture when farmers turn unproductive swamp land into farm fields within a year by tiling the land. A tiled system is a huge, wide french drain dug with a back hoe by someone skilled who can excavate a grade for the bottom of the aquauct that will flow the groundwater away quickly to a pond area or some other vent area. More information is available on this website on the subject of agricultural tile science under the archives section of the home page..
The typical lawn drain system french drain is covered with weed cloth, as all hand excavated french drains should be, and then covered with 3″ of dirt and 2″ of sod to finish the french drain. These types of hand excavated french drains start with a 12″ strip of sod being cut with a hand sod cutter and a circle of sod 4 feet in diameter cut where the dry well will be located, if a drywell is used. All sod is cut in 12″ width and 12″ length and stored on plastic in a shaded area and kept wet. When completed, the lawn french drain is installed with the dirt and sod layers placed on top of the weed cloth covering the rock in the french drain.
Lawn installed french drains will wick groundwater into the french drain from approximately 6-10 feet or more on both sides of the french drain and pull groundwater from these areas in the top 18″ of soil where most of the groundwater from rain is concentrated, where formerly the groundwater would have stood for days or weeks during and after hard rains.
Hand excavated french drains are long lasting and functional. When you are doing research into the structure of french drains, specify hand excavated french drains with 3/4″-1 1/2″ river rock, and the engineering that I have shared with you in this blog on home drainage. Never use gravel as some french drain articles advise. That type of french drain attempt does not contain enough air and the gravel compacts into a worthless gravel filled ditch, not a french drain. Never use the perforated pipe with a sock over it. They clog and do not function for long due to the fact they are easy to plug with dirt that is usually placed directly on top of the pipe and sock. If the bundle of road or weed cloth method filled with gravel is used, this will clog as well and is simply worthless in function.
So that’s about the nuts and bolts of it folks. Lots of energy in the planning, siting, environmental and neighbor considerations is required as well as the massive amount of wheel barrows up and down hills with rock and dirt.
Naturally you will find more detailed information by reading the home drainage category you are interested in under the archives section of my home page.
Absolutely nothing beats the work of trained home drainage professionals who do it every day. Eyes and experience are not bred into the nature of the home drainage installer. The amount of patience, strength and energy that it takes to plan and excavate cosmetically a hand excavated french drain groundwater removal system can be large depending on the individual project.
And last but also important is the reality that there is no one quick fix for every home drainage groundwater problem. Sometimes the best call a home drainage contractor can make is to explain the unknown factors that may be causing the problem and pass on bidding the project all together. Sometimes no good alternative is available because of the quantity of groundwater, the location of the groundwater, the source of the groundwater or the depth of the groundwater that is positively identified as a year round running spring not apparent only when rains saturate the area. I stress the words “year round” as mandatory qualifying data with respect to identifying the source of the groundwater as a spring.