This article is the forth installment of the Foundation Repair Guidelines for Homeowners series. The first three articles covered information on structural repair, site analysis, foundation repair proposals, preventing foundation damage, and basement leaks. Part one of this article discussed the importance of ground water management, not only as essential to a complete foundation repair plan, but as a proactive approach to preventing foundation damage and basement seepage from occurring. Groundwater Control Part 2 discusses passive groundwater control strategies and repair solutions to relive or eliminate excess hydrostatic pressure present on your foundation.
The best approach to correcting water seepage, moisture issues and in certain cases, preventing the need for foundation repair is to remove or control the source of the problem in addition to repairing the foundation. As previously noted in my last article lack of proper drainage causes pooling water around your basement which leads to hydrostatic pressure on the walls. Hydrostatic pressure can result in foundation damage, allowing foundation walls to crack, deflect inward, settle vertically, and allow water infiltration into the basement or crawl space of your home. Common examples of basement seepage issues are foundation cracks, slab floor cracks, tie rods leaks, and pipe penetrations.
A great number of foundation repair and basement waterproofing problems can be controlled by handling rainwater and surface drainage properly to redirect the water away from the foundation. Even when foundation crack repair, subsurface drainage systems, and steel pier underpinning is required, removing or controlling water at the source is necessary.
The most basic solutions to relieving groundwater pressure include redirecting surface water away from the structure. There are numerous methods that can be utilized for groundwater control based upon the existing site conditions. The groundwater management systems discussed in this article focus primarily on the maintenance of existing drainage systems.
Maintaining Gutters and Downspouts:
Maintaining your existing gutter and downspout system is an important step in groundwater control. Clogged gutters will overflow causing rainwater and roof runoff to free fall one or two stories to the ground surrounding the foundation. Water leaking into the ground near the foundation of your home is undesirable, as it is likely to erode the soil and backfill and create excessive hydrostatic pressure. Additionally the water seeping into the soil can lead to settlement of the foundation caused by variations to the soil moisture content.
The most common recommendation for gutter maintenance is to have the gutters cleared of debris (leafs, twigs, pine needles, etc.) three to four times each year, with the change of seasons. After the gutters are clear, check to make sure that downspout extensions divert roof runoff at least 5 ft. beyond the foundation and that the water discharged pitches away from, not toward the house.
Roofs collect a massive amount of water; in fact the average 2,045 square foot roof will collect 1,275 gallons of water in a one inch rain. Extending downspouts away from your home is essential to preventing future foundation damage and keeping your basement or crawl space dry. Directing water on a positive grade away from the foundation reduces the amount of water that can percolate downward through the soil adjacent to the foundation walls, where it can exert hydrostatic pressure.
Sloping Concrete and Pavement Surfaces:
An often overlooked cause of foundation damage is settlement of paved surfaces such as concrete, blacktop, and brick paver stones. Concrete slabs crack or sink primarily due to poor soil preparation, or washout of material that originally sup¬ported the slab. When concrete or paved surfaces settle the result is often improper water run off toward the foundation of the home. Further, once cracked, water penetrates the slab more easily, and the freezing and thawing of this water expedites the potential for damage to the foundation.
There are several options for repairing concrete slabs that slope toward the foundation. The most common approach is to remove the slopping concrete and install new concrete at the proper pitch. An alternative to concrete replacement is called mudjacking, or slabjacking. The process hydraulically lifts existing damaged concrete to the original position. Since it typically costs about half as much as total replacement, it is often an alternative worth exploring.
Improperly graded home sites often lead to future foundation issues. Grading should always divert water away from your home as to not allow water to pool around the foundation. Surface grading should be sloped away from the foundation at 5% or greater pitch for the first ten feet from the foundation. The BOCA code is even more conservative, requiring a 1 in 12 (8.7%) slope.
Restoring the site grade requires specialized equipment and trained experience installers. Even when foundation crack repair and foundation underpinning is required, removing or controlling water is essential in providing permanent foundation repair. The best approach to groundwater management and foundation restoration requires a qualified professional to provide a comprehensive site evaluation.
Installation of trench drains, extending downspouts and sump pump discharge lines below the existing grade are the most basic groundwater management solutions. Effective groundwater management, installed in conjunction with foundation crack injection, interior drainage and sump pump installation provide an effective combination to prevent basement leaks and foundation damage.
Additional information on foundation repair, basement waterproofing and foundation repair can be found in the first three segments of the Foundation Repair Guidelines for Homeowners series.