How Soil Mineral Content And Planted Trees Place Foundations At Risk

by Diane Barnes

Two very common causes of foundation damage are expansive soils and moisture-sucking tree roots. To prevent unnecessary foundation damage and repair, a homeowner should investigate what type of soil surrounds the proposed or existing foundation, and they should also take the foundation into account when planting trees.

Expansive Soils

House foundations face a high risk of cracking and damage in regions that have "expansive soils." Expansive soils consist of minerals that expand when exposed to moisture.

If a foundations is built into expansive soil, it is highly susceptible to varying weather conditions. If a region has vacillating periods of high moisture and drought, the soil will respond by swelling and shrinking, respectively. The increase of soil volume in wet periods places stress on the foundation, causing cracks, and the decrease of soil volume in droughts weakens the house's support system.

What To Do: Before building a foundation, a homeowner should invest in a professional soil analysis to determine whether expansive soils are present. Then the foundation can be properly constructed so as to minimize the surrounding soil's impact on the completed foundation. For homeowners with existing foundations, a soil analysis can still help determine the condition of the area surrounding the foundation and create a watering regimen that is adjusted for high- and low-moisture periods. 

Trees And The Soil

The risks that expansive soil poses to a house's foundation does not end just because a homeowner works around the soil conditions. Many homeowners love the idea of a tree-shaded home; however, even though surrounding a house with trees could potentially cut down on energy costs, those trees can wreak havoc on the foundation. The risk is even greater if expansive soil is present. 

Tree roots can absorb an astounding amount of water from the surrounding soil--as much as 200 gallons a day. This can have a major impact on house foundations because the roots pull water from the soil around the foundation. Even trees that are not planted close to the house can have roots that grow quite far away from where the tree was originally planted.

In regions with expansive soils, the impact that root absorption has on the surrounding soil is even greater. Thus, even if the homeowner consistently waters the soil near the foundation, the trees can mitigate the progress and foundation damage is nearly inevitable.

What to Do: Before planting trees, take into account the tree type and how far away from the trunk its roots will potentially grow. A homeowner should consider installing a "root barrier," which is an underground wall between the tree and the foundation. Root barriers prevent the tree from extracting water from the soil surrounding the foundation, and keep the roots from stretching into that area. In cases where existing trees are already causing damage, the homeowner's only option might be removing and replanting the tree.

For more information, contact a business such as John Norris Foundation Repair LLC.

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