What Are the Signs of Problems with the Foundation Drainage System?

Drainage pipes are usually absent. If there are any pipes, they are sections of clay brick that have been displaced by ground movement. Moisture-retaining soil, such as clay and sand, surrounds the building. The foundations were often poured on top of a thin layer of sand without an adequate capillary break, which allowed moisture to rise into the structures.

Drainage systems were often not installed. In exceptional cases, they might have been constructed using concrete or brick pipes, without inspection chambers. Inadequate ground slopes and a shallow foundation structure. Rainwater and drainage water are combined into the same piping system. Rainwater management is often inadequate. The walls of basement rooms in contact with the ground were often insulated and protected against moisture from the inside. Moisture from the outside penetrated the structures, causing moisture damage and weakening their structural integrity.

A false-basement structure in which the lower part of the wooden frame is located close to or below ground level. Inadequate drainage and moisture control often led to damage to the wooden structures. Drainage pipes were made of concrete or brittle plastic. The use of inspection chambers for concrete drainage pipes became more common. Guidelines regarding drainage were unclear, and drainage systems were often omitted or installed at the wrong elevation relative to the foundation structures. Sand was used as backfill, which absorbs moisture and clogs any drainage pipes.

Rainwater and drainage water are combined into the same piping system, which increases moisture stress on the foundation. Rainwater management is often inadequate. False foundation structures remain common, and the moisture problems they cause persisted, especially if the subsoil drainage was inadequate or improperly installed. New building materials and methods, whose long-term durability and compatibility with traditional structures are not always known. Subsurface drainage systems made of single-layer plastic agricultural drainage pipes. The pipes were often incorrectly installed above the bottom surface of the footing. The covers of inspection wells were often left hidden underground.

The pipes were often installed too high, and the backfill was not made with capillary gravel. The dam plate was not extended all the way to the bottom of the footing. The drainage pipes were generally made of single-layer plastic agricultural drainage pipes. The elevation of the pipes relative to the footing was often incorrect, and the covers of the inspection wells were buried underground, if they were installed at all.

In shallow-foundation structures, more fragile field drainage pipes were often used. Deficiencies in design, installation, or maintenance can lead to moisture problems. The upper edge of the dam plate is often buried underground without a protective strip, causing soil to clog the ventilation gap.
Rainwater was not always directed far enough away from the property.