Why Use Root Barriers to Protect a Structure's Foundation?

When houses or other structures are built upon clay soil, there are some serious problems that can occur. Expansive clay soil will shrink as it dries out, and as that occurs, any structure that is constructed on top of it, will tend to move downward, as the soil will shrink as it dries. If the soil is drying on one side of the structure, and not on the other side, there is a real problem to the structure, because of the stress on the one side and not the other. This is called differential settlement, and can literally tear a house apart.

Root Barrier

A root barrier can be installed between the concrete foundation and the trees that are adjacent to the house and their mature height to the foundation and where the expansive clay soil is located. This will prevent the trees from sucking up the moisture in the soil which will keep it from shrinking.

Draw an imaginary straight line from the trunk of the tree to the edge of the foundation. This will also protect damage from occurring to flatwork concrete like sidewalks and driveways. Sometimes the shrunken soil can be reversed in this way, as the soil becomes re-hydrated, it will cause it to expand, thus lifting damaged areas back to their original position.

Any impermeable material that is durable, and can be buried for an extended period of time, can be used to create a root barrier. It should be installed to a depth of at least 30 inches and should extend above the surface enough to prevent the roots from growing up and over the top of the barrier. An impermeable barrier is preferred because, even though there are permeable materials that would work, they should be used sparingly, and under special circumstances, because the impermeable barriers keep the moisture in the soil near the foundation.

Hydration Tips

Trees with large tap roots, such as pecan trees, can help alleviate some of the moisture problems, as most of the water is retained in the tap root, and not in the soil near the house. The installation of a properly timed water system can help keep the soil around the foundation of the house in a properly moisturized condition too. In the dry season, water can rehydrate the clay areas that are susceptible to the dryness.

The installation of a root barrier, or a root cap should only be undertaken by a qualified arborist or tree expert, so that the health of the tree can be considered as well as the prevention of moisture loss near the house. The decision must be made where to place the root barrier so that the tree will still be able to live, yet save the foundation of the house. If the root barrier is installed between and lots of flatwork is positioned, there may not be enough moisture in the area for the tree to continue to survive.

Planning

Root barrier planning should be undertaken at the outset of construction of the house or structure, taking into account any trees that are to be planted, or are already growing on the property. If the house is being built on expansive clay soil, the root barriers can be put into place during construction to accommodate the positions that trees are to be planted, or to take into account where trees currently are growing already.

Planning early and taking stock of what kind of soil with which you are working, can pay great dividends in the long run, and save a great deal of trouble and money. If you take care of a potential problem before it materializes, you are much farther ahead of the game.

Editor's Note: Henry Hernandez has repaired several foundations from all over the nation throughout his carreer. He has done most of these repairs with www.stabilicore.com. You can find Henry on Google+.

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