DRAIN AWAY™ - An Improved French Drain System for Correcting Water Drainage Problems in the Dallas Fort Worth Area Prepared by the Staff of Granite Foundation Repair, Inc.

One of the causes of foundation problems in the Dallas Fort Worth area of Texas arises from the accumulation of water near a concrete slab foundation or pier and beam house. The water may accumulate on the surface, or it may accumulate below the surface, or both. An accumulation of water may cause localized foundation upheaval or uplifting. Water accumulation may also lead to erosion of the soil under an area of the foundation.

Foundation upheaval occurs because as water migrates under the foundation the Dallas Fort Worth area moisture sensitive expansive clay soil swells. A heaved slab foundation tends to take a set, which may stop it from dropping to its former level.

Water migration may also cause foundation damage and soil subsidence due to erosion. Once clay soil expands beyond its limit of plasticity, it loses adhesion, turns to mud, and is squeezed out due to the weight of the foundation. Eventually, a slab foundation will drop due to the loss of soil. A pier and beam foundation may also drop, as interior piers are often undermined with erosion, as well as erosion of soil around the concrete perimeter beam.

Poor drainage occurs when there is inadequate slope in the yard. It is not always practical to adequately change the slope by grading the yard. Poor sub surface drainage may also occur as a result of tilling land for lush bushes and flowers. The soft, well tilled, sandy loam acts as a sponge that holds water at the foundation perimeter.

Surface water can be removed by the creation of a surface drain system. This consists of water collector boxes spaced every 6 to 10 feet and connected to buried drain pipe. Most often, the surface water can be lead away to a lower place in the yard, and terminated with a pop-up water release valve.

Sub-surface water, which can accumulate around the perimeter of a foundation, should be removed with a French Drain. When practical, the French Drain system should extend to a depth of 6 inches below the exterior perimeter beam of a residential or commercial foundation. Sometimes rock or slope considerations may limit the drain to a shallower placement.

For French Drains, Granite Foundation Repair, Inc. recommends the DRAIN AWAY™ Prefabricated Drainage System. This is a three component system consisting of a polystyrene cuspated core and a perforated drainage pipe, all covered by a geotextile filter fabric.

How Does DRAIN AWAY™ Work? The geotextile filter fabric allows ground water to pass through to the core while restricting the soil particles from entering, eliminating clogging of the core and drain pipe. The cuspated core collects the water and channels it to the perforated drain pipe. The system in a trench will intercept and collect ground water near the foundation, and when combined with surface drains, will also eliminate wet surface areas and help prevent erosion.

The Evolution of the French Drain

Before the advent of the DRAIN AWAY™ system, the French Drain system went through several stages of development.

Early on, a French Drain was created by digging a large trench, filling the trench with aggregate/gravel, and covering the top of the trench with a few inches of soil. Eventually soil would clog the gravel and prevent drainage.

In the next evolution, a perforated drain pipe was buried in the gravel to facilitate the removal of the water. Again, the soil would eventually clog the gravel, preventing water from reaching the drainage pipe.

The next improvement, to prevent soil clogging of the of the aggregate, was to cover the gravel and perforated drain pipe with a textile cloth. The textile cloth filtered out the soil, allowing water to pass.

The DRAIN AWAY™ system is a vast improvement over earlier drainage systems. The specially manufactured, cuspated, polystyrene interior allows water to flow unimpeded into a perforated drainage pipe. All of this is contained within a specially designed and manufactured geotextile cloth.

Advantages Of Using DRAIN AWAY™

• Requires smaller trench
• Less excavation
• Less scarring of surface
• Less space (width) required for drain
• Removes ground water faster than aggregate/gravel

How much will it cost to fix a foundation with this drainage system? The DRAIN AWAY™ system of French Drainage is comparably priced to older methods. The material cost of DRAIN AWAY™ is offset by reductions in other materials and labor. The system requires a narrower trench, less soil removal from the job site, and the elimination of the need to haul in gravel with heavy equipment. While the addition of a drainage system reduces further damage and may eliminate the cost of foundation repair in the future, it will not fix an existing foundation problem.

Will the installation of a French Drain or surface drain reduce or eliminate the cost of foundation repair? When foundation damage has occurred as a result of poor drainage, there may still be a need for foundation repair. This is due to either erosion, or the lasting effects of upheaval.

Due to the slow migration of water through clay soil under a foundation, clay soil may require a year and often more to begin to subside. Often, a slab foundation or concrete perimeter has taken a permanent "set", and will not drop to its former elevation. Then it is more practical to underpin the foundation to minimize movement as much as practical in order to minimize interior and exterior wall, ceiling, window, roof and floor damage. If the drainage problem has caused soil erosion under a foundation, drainage improvement will cause sub-foundation loss of soil moisture, and soil shrinkage. The foundation loses support and further drops. If a foundation has already dropped due to erosion, it is appropriate to underpin it as soon as practical to minimize further drop.

Crew installing Drainage system with revolutionary DRAIN-AWAY

Actual DRAIN-AWAY Material

Diagram of the Drainage process using DRAIN-AWAY

Manufacturer's Specifications: DRAIN-AWAY™ PANEL DRAIN

DRAIN-AWAYTM Panel Drain (Double Sided Core) is a prefabricated geocomposite drain consisting of a formed polystyrene core, enveloped with a non-woven, needle-punched polypropylene filter fabric. The fabric permits ground water to permeate, yet prevents the adjacent soil from washing through to the core. The channels of the core allows the water to drain to an exit, or pipe below. Panel Drains include extra fabric at the bottom of the drain to accommodate a perforated pipe, Thus eliminating extra steps in the field.

Material Specifications:

Note: DRAIN AWAY™ is a trademark of Drainage Products Incorporated. Drawings courtesy of Drainage Products Incorporated.