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6 Reasons Foundations Settle

Nov 22, 2013 • By Matthew Stock with Michael Likvan.

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All houses settle.  That’s a fact.

However, settling can be a minor event that is more or less expected or it can be a cause of major damage to the home.  The expected kind happens shortly after construction when even the best-compacted soil may compact a little bit more with the weight of an entire house on it.  This settling may cause a few small cracks in drywall but is usually not a major problem.

The other kind of settling can happen at any time and it can cause damage as severe as tipping or bowing foundation walls or a dropped foundation that has to be raised and stabilized by underpinning.  This kind of settling has a number of causes which, in alone or in combination, can create a real nightmare for the homeowner.

6 Reasons Foundations Settle

  1. Soil Type – Clay soil, also described as expansive soil, is reactive to water and expands when saturated and contracts when desiccated.  Other soils, like loam and sand, are not as absorptive as clay, offer better drainage and expand and contract far less.  Clay soil is the most common type in the general area around Chicago, including southeastern Wisconsin.
  2. Location – Many new residential developments are located on filled areas that may have once been low ground or wetlands.  This fill soil will continue to compact and settle far longer than undisturbed soil.  Also, many areas have high water tables or underground streams that can erode and undermine underlying soil.
  3. Foundation Construction – Older poured concrete foundations that may have been constructed without steel reinforcement or with poorly mixed concrete may not be strong enough to withstand the movement of soil that is created by hydration and desiccation.  Masonry foundations, such as concrete block, stone or brick, are held together with mortar and the mortar joints form numerous weak points in the wall that may crack.  Further, shallow foundations or any structure that is close to the surface, like crawl spaces, porches and garages, will yield to ground movement more easily than deep foundations.
  4. Drainage – Homes without a working drain tile system, such as older homes where a terra cotta tile system has broken down, will accumulate water around the foundation that will saturate the soil around the foundation footings.
  5. Vegetation – Plants and trees that are located close to a house will quickly desiccate the soil around the foundation during times of dry weather and drought.  The soil compacts and draws away from the foundation when it dries out, which can allow foundation walls to move as the pressure exerted by saturated soil is eased.  It also creates compacted pockets of soil under the foundation and allows these unsupported sections to drop.
  6. Extreme Weather – Heavy rains can over-saturate the soil around a foundation, increasing the lateral pressure that the soil applies to foundation walls and increasing the chances of wall movement.  Drought conditions, on the other hand, pull moisture out of the soil and create gaps and sections of compacted soil that allows walls to move and foundations to drop.  Extended freezing conditions can also expand soil close to the surface.

Unless the problem lies with faulty construction or poor siting, most of these problems can be avoided by properly managing water outside the home.  Even if they do occur, they are reparable but a homeowner facing such a problem requires the advice and services of a full-service foundation repair contractor.  At U.S. Waterproofing, our foundation repair experts use engineering data and the latest technology to recommend and implement permanent, cost-effective repairs to damaged foundations.  Please ask us for a free consultation if you’re seeing signs of foundation damage.

Tags: foundation settle, settling foundation

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