Why Micropiles might be the best repair technology for you home.
Everyone who has lived on the Front Range for very long has heard about our expansive soils and the damage these soils can cause to a foundation. If you are having problems with your foundation, it is likely that swelling soils are part of the problem. Soil swells because of the presence of certain minerals, most of which are aluminosilicates formed by the weathering of the granite that made up the Ancestral Rocky Mountains and current Rocky Mountains. These swelling, or expansive soils change volume with changing water content: shrinking or swelling as they wet or dry out. In many cases, these soil volume and moisture content changes happen seasonally, in others they happen on a longer term horizon: changing with changes to a local groundwater patterns, sometimes due to local development (i.e. a new golf course, parking lot, etc. being built up-strata from your home). Whatever the cause, the result is soil swelling or contracting and causing damage to your home.
One thing that makes our soils unique is that our swelling soils can also be very dense and hard. Frequently harder than 40 and even 50 blow-count soil (to read more about soil density and bearing capacity testing, please read this). In many areas (Erie Air Park, Rock Creek in Superior, many neighborhoods in Broomfield, Arvada, Thornton and Denver), there are layers of very dense, expansive soils overlaying more dense, expansive soils. These soils can be very difficult to advance a helical pier through. VMC uses the most powerful portable helical piering equipment commercially available, but this equipment is limited to about 6000 ft. lbs. of torque. While this may sound like a lot of force, it will typically only advance a pier about twenty or thirty feet into 40 blow-count soil, and will not progress into 50 blow-count soil at all. A push pier is worthless in this type of soil. Now, most of the homes in these areas were built on drilled caissons, and if they were built in the last thirtyyears, these caissons are likely 30+ feet deep. If your home’s 30’ deep caissons are failing, replacing them with 30’ deep helical piers even shorter push piers will not provide you greaterstability or a permanent solution. The only way to permanently fix a foundation built on these types of soils is to drill through the upper layers off dense, swelling soils into layers deep enough that they can’t swell and are of constant moisture content. This is why Van Matre Construction has invested substantially into the best micropile drilling equipment. Our drills and pumps can be disassembled, carried by a crew into a basement, and re-assembled allowing us to drill down as far as needed to reach competent soils; we can drill as deep as 150’ into solid bedrock, if needed.
Micropiles are also known as minipiles, pin piles, needle piles, and root piles. The micropile casing generally has a diameter in the range of 3 to 10 inches. Typically, the casing is advanced to the design depth using the appropriate drilling technique. Reinforcing steel, typically an all-thread bar, is inserted into the micropile casing. High-strength cement grout is then pumped into the casing. The casing may extend to the full depth or end above the bond zone with the reinforcing bar extending to the full depth. The finished micropile (minipile) resists compressive, uplift/tension, and lateral loads and is typically load tested. Capacities vary depending on the micropile size and subsurface profile. Allowable micropile compressive capacities of more than 500 tons have been achieved.
While micropiles are more expensive than helical piers, none of these repairs are inexpensive: paying a little less for helical or push piers that won’t reach a depth substantially greater than the house’s existing, failing caissons is a colossal waste of money. If you have had the misfortune of having foundation problems, don’t compound the problem by spending good money on a ‘fix’ that’s destined to fail. Make sure your money will not be wasted and buy the repair that will last.
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If your windows or doors used to open and close easily and are now tight or rubbing,you could be experiencing foundation movement.
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