5 common foundation and home drainage problems
Home drainage problems can be nasty. The homeowner has many responsibilities with respect to caring for their home. Your home may be the largest investment you will ever make. The most money that you will ever spend on an item in your entire lifetime.
The importance of maintaining this investment doesn’t really need to be driven home. We all know the importance. Many homeowners do not realize that items pertaining to their foundation, and the lack of properly constructed and plumbed hand excavated french drain groundwater removal systems, and their foundation, are tied together with the overall health of the home.
When hydrostatic pressure caused by groundwater accumulating next to the homes’ foundation, or within the crawlspace, begins to break up the structure of the home, homeowners seldom see it happening.
Homeowners see the results of the process many years later when it is a real big problem.
The most common realization comes to the homeowner when they want to sell the home, and the pest-dryrot and structural inspection discloses the problem to the buyer, and makes the repair of the problem a requirement to the new buyers’ loan. The most common problems I find, in my work as a licensed, bonded and insured drainage and masonry contractor. are as follows.
- The foundation shows evidence of undermining of the foundation footing. A common fact pertaining to this, is that the foundation was poured without the base of the foundation footing deep enough. The groundwater flows under the footing and carves out a passage under the foundation footing during hard rains. This allows the groundwater to enter the crawlspace. This is a common problem that leads to water in the crawlspace when it rains hard over a period of time.
- A common problem exists where the low point drain is not constructed properly, and is not effective. The low point drain is a length of 3″ abs solid pipe, that is poured into the base of the foundation wall at the time the foundation is poured. The low point drain is supposed to be placed in the lowest part of the interior of the crawlspace.
Sometimes the contractor did not even choose the correct location for the low point drain. The reason that it functions as a drain, when properly constructed, placed and vented, is that the pipe is glued to a device on the interior of the crawlspace that is placed at grade level, and has a fitting within the device that contains a “backflow flapper” designed to stay open when the groundwater starts to flow out, and closes when the groundwater starts flowing back into the crawlspace. The backflow device should be laid at a grade that slopes away from the interior of the crawlspace. This “backflow device” is supposed to be a backflow preventer. The low point drain is however, many times, upon investigation by the drainage contractor-mason, just a pipe poured into the concrete foundation wall, that does not vent to anything. The pipe was just backfilled with dirt on the outside of the foundation wall, and was never made to work at all. This is a common problem.
In addition, the problem many times is that when the foundation was constructed, the low point drain was installed and the floor joists for the home were not yet installed. Through rains accumulated within the crawlspace before covering with a floor, the rain made the dirt crawlspace floor wet and sink a bit, or through the compacting nature of workers walking within the crawlspace area while doing the post-beam structure of the home and placing the floor joists prior to the floor being nailed down, the grade of the dirt was compacted a few inches lower than the base of the low point drain pipe that was laid at ground level, and poured into the concrete exterior foundation wall. That puts the low point drain above grade. That’s a mouthful right?
The fact then remains that the low point drain will no longer work until a few inches of water has already accumulated within the crawlspace, if it even works then; and you have already suffered groundwater standing in your crawlspace by that time. At times, at this point, there is a necessity for the construction of a sump pump system, with a french drain system as well, hand excavated at shallow depths within the crawlspace, through the wet areas, and with an engineered slope to run water from the foundation crawlspace area approximately 25-30 feet away from the sump pump, to the sump well, where groundwater can be collected and pumped out.
A better solution is available to homeowners that have a slope on the outside of the foundation wall that slopes at enough of a grade, away from the foundation wall. The opportunity exists here for the drainage contractor to construct and plumb a hand excavated footing french drain system that slopes under the foundation footing, and continues to slope effectively away from the foundation at a grade that will run the water out to a daylighted vent location away from the home, or to a drywell constructed away from the foundation where the groundwater can perk back into the lower levels of the earth.
This type of hand excavated french drain groundwater removal system is much more effective than any low point drain, even if the low point drain with the pipe is properly constructed.
The undermined area where the groundwater has entered the crawlspace must be filled and compacted with dirt to prevent further groundwater entry. The construction of an exterior hand excavated french drain system is also advised. The exterior hand excavated french drain is the most important aspect to prevent the groundwater from entering in the first place, and to achieve the best results.
The construction of an exterior french drain groundwater removal system is the major priority, as well as any concrete reconstruction that may be required from groundwater damage to the foundation.
- A third common problem with respect to foundation and home drainage issues is as follows. Foundation vents are poured too low at construction. These vents should be located higher in the foundation pour, to allow the passage of air through the foundation in the summer months when they are opened. This dries out the crawlspace area and removes smells that can accumulate.
Many homes have foundation vents that are at ground level, or below grade level on the outside of the home. With the addition of dirt, barkdust or other debris, the vents wind up too low in the foundation wall. They are constructed below the dirt grade level, and are made to fail.
The rainwater overflowing the gutters, and the groundwater as well, runs into these foundation vents which become big holes in your foundation. The foundation vents contain a door that can be closed, but even when closed, the vent cover will not prevent the entry of water. Contractors and architects should know better, but many do not practice the due diligence of designing a finished grade, if they do know the difference.
Foundation vents need to be poured high enough on the exterior foundation wall to allow enough room for soil to be backfilled on the foundation, to create a compacted grade of approximately 6″ per 10 lineal feet away from your foundation wall. Code requires this in most cities.
The placement of a hand excavated french drain located approximately 18″-24″ from the foundation stem wall is a priority.
The grade can be raised along the home with the installation of a window well. The window well will not keep the groundwater out as it rains in the top of the window well, but will allow the grade to be raised with compacted dirt along the foundation wall, creating a better runoff by putting the top of the window well above grade. The foundation vent was poured into concrete, so the best you can do is to construct and plumb the hand excavated french drains and raise the soil grade.
- Water enters crawlspaces where the contractor building the home roto-hammered through the foundation to run abs sewer discharge pipes, and did not have the masonry skills to realize that the holes created, would leak groundwater when the hydrostatic pressure on the foundation was increased during rains. These holes must be sealed with a hydrolic cement by your mason-drainage contractor.
- Cracks or rock pockets that exist in the exterior foundation wall must be chiseled out to the point where the crack or air space stops. They must be filled with a hydrolic cement by your mason to seal these areas, and to prevent further deterioration of your foundation, and to prevent groundwater entry into the basement or crawlspace. The masonry work is usually required on the inside and outside of the foundation, if the crack is visible on both sides of the foundation. Have your mason-home drainage contractor inspect these areas for damage.