Reasons For Foundation Repair:
- Usually, the reason for foundation repair is the soil itself, and more specifically, the rate and location at which the soil is hydrated. Most of the time, there is either too much hydration which causes the soil to swell, or too little which causes the soil to shrink. In the Pacific Northwest, nearly every property experiences this dynamic due to our rainy climate. Variance in soil density becomes a foundation issue when the shrinkage and expansion is not uniform. In other words foundation issues due to water usually occur when one part of the foundation is surrounded by soil that is under pressure to expand and contract, while another remains less vulnerable to these changes in structure.
- Many times soil moisture issues arise because the soil was at one or the other extreme during the construction of the original foundation. If the soil was very low in moisture during the original installation, most of the foundation issues will be quite visible later, as the edges of the slab will regain moisture first as conditions normalize. On the other hand, if the soil was hydrated more than usual during the foundation install, then the concrete slab will hold moisture exept at the perimeter. This is because of wind and heat that effect the outer edges of the foundation slab. This causes the outer and inner parts of the foundation slab to lose moisture at different rates. When this happens the middle areas of the house will “settle”.
- Grading and the setting of slabs is an art that is highly dependent on the elements. Here in the Pacific Northwest, it is unfortunately common to find issues of poor compaction practices. When the soil is either insufficiently, or improperly compacted during the installation of a foundation, the home will be subject to settlement as the supporting soil centralizes it’s gravity.
How Foundations Can Be Repaired:
When a foundation has obvious cracks, or other signs of foundation settlement underpinning can be a good solution.
Underpinning or pin piling are effective foundation repair process which strengthens weakened foundations. Here in the Seattle area, and the Pacific Northwest, it is common for foundations to be weakened by variance in soil moisture as described above. We have found that this solution is most cost effective for customers that have foundations that cannot support the structure that is on it.
There are different methods of underpinning, and the technique is dependent on each individual situation. Here is the general process for foundation repair in the Seattle area:
A common underpinning procedure is the mass concrete example. This technique is best when the underpinning can be shallow. We excavated the offending soil, properly compact the remaining earth, and inject concrete into the remaining areas in order to shore up the existing foundation. We find that this technique can add a great deal of life to a failing foundation at a cost that will save quite a bit of money over the long term.
Another underpinning method is beam and base. This method is similar to mass concrete but involves a new concrete slab rather than concrete injection. A new slab is set below the foundation after the home is lifted, and beams are set in order to serve as support for the renewed foundation. In this manner, the weight of the house is transferred to the beams at the weak points, which is in turn transferred to the wider slab. This method is best when a home is settling at specific and predictable areas such as the center or parameter of the house.
Another method of foundation repair is mini-piling, or pin piling. This method involves transferring the load of the structure and the foundation to stable soils found deep under the ground. Usually, the depth of the soil exceeds 5 meters. The constructed piles are cased in steel and have a diameter ranging from 15 cm to 30 cm. The piles are driven into drilled holes, making them rest on a stable soil below ground level. Some piles may be constructed as to reach 15 meters below ground.
Other times, masonry repair products like hydraulic cement are adequate solutions to a crack or settlement of a foundation. While this is not a permanent solution, there are times when it makes sense to patch the issue rather than removing it.
Sometimes one of our customers has a small cosmetic issue in a foundation wall, or the foundation has not settled to the point where underpinning is necessary. In these cases, Kunkel Moving and Raising will always advise the property owner of the long term cost to benefit ratio of patching. Please feel free to reach out to us via email for free advisement. You may also call us anytime at 1-800-490-4220. We look forward to hearing from you!