Why Weeping Tile is Installed Around a Home
Shortly after the beginning of the 20th century, weeping tile / drain tile / weeper / perimeter drain / footing drain installation became a standard building practice (code). Weeping tile is installed to drain away the ground water which accumulates at the base of the foundation. A weeping tile system is installed in a way that permits water to flow away from the foundation; this is accomplished by installing a leader line (pipe) that slopes downwards to the stormwater sewer on the street, or by draining the water into a sump pit inside the basement. Prior to 1980 (approximately), perimeter drains (weeping tile systems) were installed using sections of clay pipe joined together end-to-end; today, a 4" diameter continuous perforated plastic pipe with an anti-silt fabric is typically used. The picture below shows a typical weeping tile installation for a new home (circa 2009).
Below is a close-up view of the weeping tile tie-in to the leader line which is connected to the storm sewer.
Once the weeping tile is installed it is typically covered by 2 cubic feet of 3/4" crushed stone per linear foot as shown below. The window well drains in this image are connected to the weeping tile system installed beneath the gravel layer.
Once the gravel layer is poured, it should be wrapped with filter fabric in order to minimize the amount of sediment that is able to make its way to the weeping tile. This is not a common practice followed by new home builders; however, it is a standard practice for AquaGuard Injection & Waterproofing® because obstructions in the drainage system are to be avoided as they reduce the drainage efficiency of the installed system.
Clogged Weeping Tile
The image below is of a clogged weeping tile system in need of weeping tile repair. Note: weeping tile repair is somewhat of a misnomer; in fact all that can be done to repair weeping tile is to replace it, or flush the weeping tile if it is clogged with sediment. Both weeping tile replacement and weeping tile repair require excavation of your foundation.
The silting or clogging of a weeping tile system is a fact of life and the likelihood that it will occur is increased by the number of years the system is in service. The silting of weeping tile is generally greatest beneath downspouts.
It is generally believed that weeping tile replacement will certainly "fix" any and all basement leaks and will transform your wet basement into a dry basement; this belief is questionable and merits closer investigation. Here is a close-up view of new weeping tile:
As you can see there are thousands of perforations in the weeping tile along its length; therefore, an obstruction in one location will not prevent water from entering the weeping tile elsewhere. Furthermore, the gravel layer surrounding the weeping tile also permits water to flow along the foundation footing, whether the weeping tile is clogged or not (although, if the gravel layer is full of silt, water will not flow). Additionally, since a weeping tile system is installed around the entire perimeter of the foundation, water flow is not unidirectional; consequently, an obstruction in one area will effectively force water within the weeping tile or gravel layer to travel in the opposite direction to the drainage point (leader line or sump pump). Like electricity, water simply follows the path of least resistance.
Is Weeping Tile Replacement Necessary?
On a final note, AquaGuard Injection & Waterproofing® has repaired 1000s of basement leaks in new homes with virtually brand new weeping tile systems; clearly, weeping tile replacement is not the be all and end all of basement waterproofing solutions. In fact, gaps in the wall, typically cracks or holes, are usually responsible for most wet basement problems. Furthermore, even though weeping tile is functioning properly, there is always hydrostatic pressure on the outside of the foundation walls. This hydrostatic pressure is due to the existence of the water table and the characteristics of surface tension which pull the water table upwards until the water mass is so great that gravitational forces overcome the intermolecular forces associated with surface tension.
Read our companion blog post: You have a leaking basement, is it time to replace your weeping tile?