This article is the third install of the Repair Manual for Homeowners. Since we reviewed the site analysis and repair proposals, it is time to discuss the importance of groundwater management not only as an important component of a complete foundation repair plan, but also as an active approach to damage to foundation prevention.
Groundwater management is important to ensure drying of your infrastructure or slipping, as well as to prevent damage to the foundation. The structures of the lower level (space for basements and slabs on the foundation) are designed to counteract the combination of both hydrostatic (water) and ground pressure (pressure applied to the wall by surrounding soils).
Hydrostatic pressure on the foundation wall occurs when the groundwater level rises above the foundation at any point. Thus, the walls below the groundwater level, also called water runoff, experience this pressure. The groundwater level and, therefore, hydrostatic pressure can vary seasonally (usually higher in spring), daily or even hourly under certain circumstances. Hydrostatic pressure can be sporadic, based on changes in the groundwater level or in continuous areas where the height of groundwater remains on the wall of the foundation or on the floor plate.
When full hydrostatic pressure is applied to the foundation, it remains constant until excess water drains through the soils surrounding the foundation or slab. This added ground pressure can affect the design of the foundation or slab of your home. However, the groundwater level is not the only factor contributing to hydrostatic pressure. Certain types of soil, planned clays and silts, for example, exert lateral pressure on the foundation equal to their density, and may exceed the level of pure hydrostatic pressure in the presence of groundwater.
Most homeowners often do not consider problems with the foundation, and the seepage of the foundation or bypass space can be avoided with routine maintenance; although a large number of basement repairs and problems with waterproofing basements can be prevented by properly turning to rainwater and surface drainage. Improper groundwater drainage can lead to the pooling of water around the external basement, which leads to hydrostatic pressure on the foundation walls.
Hydrostatic pressure can damage the foundation, allowing the walls of the cracks to deflect inward, settle vertically and allow water to enter the basement or the space to bypass your home. Most of the problems with water in the basement are generally not problems with the basement, but problems with groundwater management and drainage. Therefore, it is better to manage the flow of water to treat or repair foundation damage or sediment, and not just rely only on waterproofing or repairing the foundation. Groundwater can enter your home in many ways. Common examples of water penetration are base cracks and floor slabs, screeds or pipes.
Groundwater management begins with an assessment of the existing site conditions. As a homeowner, you have two fairly broad choices for assessing the condition of a site. You can perform routine maintenance yourself to reduce potential damage to the foundation and control the seepage of the foundation, or seek professional advice from a contractor specializing in repairing the foundation and managing groundwater. In the event that foundation damage is present, the best course of action is a professional assessment of both the foundation and site conditions that contribute to the damage to the foundation.
There are many methods that can be used to manage groundwater based on existing site conditions. The simplest solutions for restoring or eliminating excess hydraulic pressure present on your foundation are associated with passive control of groundwater. Various methods for managing passive groundwater include proper sorting to control surface runoff, expansion of drainpipes, granulated backfill, including installation of base drainage, as well as proper sorting of concrete and asphalt surfaces.
