For centuries, builders have had a major obstacle in building lasting structures; settling. Settling is a natural occurring phenomenon where the soils and bedrock of the earth are in constant, albeit very slow, movement. When tectonic plates move we call it an earthquake. When soil under your house moves, we call that settling.
Settling comes in various ways, and various threats to your foundation. Hydrostatic pressure can cause walls to buckle into your basement, or rarely sheer a wall in over a floor. This type of movement is horizontal and is easily fixed with PowerBraces, or similar steel I-Beams. The other type of movement is sinking, and as the name suggests, is vertical in nature.
Sinking occurs when the soil under a foundation for any number of reasons moves down or out and away from that foundation. Usually this occurs in sandy soil, or in thin layers of clay soil with lighter soil underneath it. In short, It's harder to detect and costlier to repair.
Many remedies have been used in the past, in fact there are old settler stories of the Great Black Swamp where early builders had to sink stones and logs for days before they could build a suitable cabin! Sounds like the Swamp King in Monty Python's Holy Grail; "But the fourth one stayed up!"
Today, we can safely stabilize sinking foundations using a high-tech spin on a solution the Vikings developed for their notorious fleets of ships. The process is called "piering."
To build piers that could stand the violent seas in the Nordic regions, the Vikings used large timber poles with a screw-shaped metal fitting on the tip to drive down deep into coastal soil to provide support. The practice later became more popular in England for lighthouses during the industrial revolution. In America, this anchoring practice known as "helical piering" was used for anchoring guy-wires for telephone and power poles.
Left: This is a modern helical head. It is made of galvanized steel and can be drilled over 100 feet into the earth!
So what are the signs of sinking, and how can you spot it in your home? Well, the obvious signs are cracking in drywall or exterior walls—though vinyl siding may be covering these clues.Other signs include doors and windows that won't shut or open, or worse, cracked glass in windows that cannot be explained otherwise.
So what makes these piers work? It's pretty simple actually, the soil the foundation is in moves. All soil moves, but it is slower the deeper into the ground you dig, eventually hitting "load bearing soil," or bedrock. By driving steel shafts down to these depths, the shaft itself becomes a load bearing member.
The piers work as a network around the footer to stabilize the entire structure. This network of piers is then fitted with locking collars that are then carefully adjusted with pneumatic pressure until the foundation is stabilized in a level manner.In some instances, the foundation can be "lifted" and a small amount of sinking may be recovered.
Here Lee Blodgett, part-owner, is monitoring the foundation with a laser-level as he applies about 2,000 psi to each pier simultaneously.
As the brackets on the end of the piers are normalized, structures may creek and "pop" back into place, although rarely (more like never) will they fall back into place entirely. We had some audio recordings of these sounds on this project, however the sounds were too faint to be adequately amplified.
What we could capture however, was the amount of lift. Here we have our static laser-level on the left, and our gray precision gauge attached to the corner of the home on the right.
Here is the before and after!
This may not seem like much, but imagine the weight of the walls on your windows and doors. Or look at the difference in the chimney!
Skinning a Cat
Like many other areas of life, there are multiple ways to fix settling. On this particular project, there was one such attempt. As the chimney was falling out and away from the home, another contractor had dug beneath the chimney and placed railroad ties as forms, and poured a large concrete pad, aimed at producing enough surface pressure to stop the chimney from falling further. It's a common technique, full of conventional wisdom. No fault at all, but the science just doesn't hold up. Foundations must be built upon something that can carry the burden.
In this instance, we found the fix a hindrance, so we had to put a relief cut into the slab, and stabilized the chimney with two additional piers.
Piering is a formidable option to sinking settling in our area, and around the world. Compared to rebuilding a foundation, the practice is about the same in cost, but much less invasive and hence, faster. While there are many aspects not covered in this blog, the basic message is hope! If you notice cracking in your walls, or sloped floors—it still might not be sinking. And if it is, it can be fixed! Here's to a safer home.
The same piers featured in our blog today are commercially used in much larger buildings, including the Ludwig Mill in Grand Rapids, Ohio
For more on that project, click here: http://www.basementdoctornorthwest.com/foundation-repair-ludwig-mill-toledo-ohio.html