Installing an interior hand excavated french drain is not going to keep groundwater out of the crawlspace or basement of your home.
No matter what line the sump pump installers give you about a guarantee, crawl space sump pump systems do not prevent groundwater from entering below grade, ever. Their guarantee is worthless. Their methods are deceptive. Their experience may be as little as absolute zero.
A sump pump installation should be used only after you have determined that either a hand excavated french drain and a compacted grade splash block of dirt and clay to enhance rain run off away from the foundation cannot be installed on the outside of the foundation wall to stop the groundwater entry.
There are many types of limitations to optimum home drainage success, with respect to the exterior of the homes construction or topography, that can prevent the installation of the correct solution. This additionally compounds things. Home drainage is often at the top of the made to fail list among all home improvements.
Installing an interior crawl space hand excavated french drain is not a very effective way to collect the groundwater, even if you need one, unless done in a specific way. Most often sump pump installations are simply a bad dream for the homeowners and the beginning of a financial nightmare as they find there way to AAA Home Drainage and hand excavated french drains.
Excavating long lengths of hand excavated french drains along the inside of the foundation wall is futile, they become long sloppy trenches without a grade, and without the ability to perform much at all. Oh sure, the sump pump goes on when the ditches fill up with standing groundwater. Big deal. Failure. The water is standing and only flowing out the end of the ditch when it has been saturating for days and is finally full of water. All that time before the sump pump goes off is damaging your homes foundation and air. That is a guarantee you can count on.
It sounds so good when some dude says his answer involves making a sump well and a trench around your crawl space foundation area. A big fat sloppy ditch is all you get. And a crawl space that will be wet until you remove the groundwater on the outside of the foundation eventually.
Some internet and television drainage pundits, as well as some builder and contractor internet sites, refer to their attempted interior crawl space french drains as trenches or ditches. A hand excavated french drain is not a ditch or a trench. Guaranteed no results is what homeowners get from these sump characters. Money lost.
These sump guy sloppy no grade ditches will not gravity flow water to a sump pump area at all. They do not even overflow fast enough to help remove the groundwater prior to the saturation of the crawl space floor.
The distances of your interior hand excavated french drains are limited to around 20 feet in length approximately. The hand excavated french drains should not be excavated deeper than around 12″ deep at the sump well, and around 8″ deep at the top of the interior crawlspace hand excavated french drain grade, in order to create a grade of 2″ per 10 lineal feet of grade, so the groundwater will flow quickly to the sump pump.
The interior crawlspace hand excavated crawlspace french drain is the same width as an exterior hand excavated french drain, 12″ wide.
Because of these logistical facts, the distance that can be covered in lineal feet for each collection line is limited when installing them to vent at a depth at the sump well of no more than around 12″ deep.
The proper way to design this type of system is to install a series of hand excavated french drains sloping from different directions to a center sump well, located in the deepest area where groundwater collects. A series of perhaps 2-3 french drains all venting through river rock and a perforated pipe to a sump pump well.
If the sump well containing the sump pump is around 18″-24″ wide and 18″ deep, and the shallow crawl space french drain enters the sump well area at a depth of 12″, this leaves 6″ of depth within the sump well in which the groundwater can build in height prior to the sump pump pumping it out. This installation has the 3″ perforated pipe installed in a hand excavated french drain aqua duct at approximately 8″ deep, sloping to 12″ deep. Get the picture?
To make it even a worse deal for the homes health, the sump pump is not designed to pump out all the groundwater at the bottom of the sump well. It either soaks back into the soil around the sump well, which is most common, or it evaporates into your crawl space over time.
The 2″ approximately of groundwater that remains within the sump well after the sump pump discharges what it can, is a good reason not to install one unless absolutely necessary in the first place. Groundwater just soaks back into the soil keeping dampness there all the time.
3″ flexible ads perforated pipe and 3/4″-1 1/2″ river rock should be installed with weed cloth in the same manner as is used for the exterior hand excavated french drain installation, as described in many articles within this blog.
Two 14″ o.d. concrete cylinders or larger, if you can get them into the crawl space, are installed within the sump well. The concrete tiles are stacked.
From my experience, this is your best option. Concrete cylinder installation only, rather than using plastic tanks or buckets, even worse, which do not function the correct way, and do not insulate for cold and sound. Plastic floats up and fails if not anchored.
Surround the cylinders with 3/4″-1 1/2″ river rock a few inches around the sump well cylinders and under them as well. By setting the tiles on top of a bed of rock, clean water is pumped through the system as the groundwater is cleaned as it runs through the river rock.
River rock is also used in interior crawlspace french drains just like exterior systems.
You are limited by engineering depth as well within the crawl space, and that in turn limits the amount of lineal feet your french drain can travel at a 2″ per 10 lineal foot grade, while also not being deeper than 12″ deep at the dry well.
Put a concrete top with some insulation over the cylinders to kill the noise of the sump pump. Try not to install these noisy sump pumps in the crawl space located right under your bedroom floor, if you want a good nights sleep in rainy weather.
Insulate the sump pump discharge, which is 1 1/2″ abs pipe, for added noise protection, and never use pvc pipe to discharge the sump pump. Sump pumps vent with abs pipe.
Do not vent the sump pump out a foundation vent allowing groundwater to simply soak next to the foundation again, effectively recycling the same groundwater over and over.
Beware of installing sump pumps into rain drain discharges that can overflow when the sump pump pressure kicks in. Usually, these sump pump discharges create pressure on the rain drain discharge system itself and over power it with pressure. The rain drain discharges overflow like fountains next to the foundation, unless the rain drain discharge system will take the pressure of the discharged sump pump, which sometimes they do, depending on age and how they were originally plumbed.
The best sump pump installations are vented well away from the home to a daylighted vent, or into a hand excavated dry well, were your exterior hand excavated french drains vent. Nice to do them both at the same time. Right? This is best done in conjunction with the installation of your hand excavated exterior french drain and dry well.
Again, I make the emphatic point that interior crawl space french drain installations will not stop the groundwater from entering your basement or crawl space. They will fail as your foundation footings keep sinking. They do not prevent trapping moisture, a problem in your crawl space, or prevent dryrot of posts and beams. Sump pump installations do not prevent other associated health problems related to groundwater entry from standing groundwater.
Unless prevented by obstacles or limitations of gravity and engineering, almost every time the home drainage groundwater solution in the end has everything to do with the installation of hand excavated french drains on the outside of the foundation to stop the groundwater from entering below grade in the first place. Often this can not be accomplished prior to a new drainage contractor deconstructing a formerly installed and failed groundwater solution attempt first, prior to often installing hand excavated french drains in the same area.