With Colorado’s expansive soils and the wild weather fluctuations we have been seeing, changes in the soil’s moisture content have been wreaking havoc on foundations in the Front Range. If your home is experiencing issues caused by foundation vertical movement (up and/or down), you may see some of the following issues:
When a house’s foundation heaves or settles, the framing moves with it. Drywall and plaster quickly crack with very little foundation movement and can give an indication of how a house’s foundation is moving. These cracks commonly show up at the corners of rooms, windows, or doorways. If it is a new home, and you see a few hair-line cracks, this is typically indicative of normal drying of lumber and is nothing to worry about, however the crack should be monitored. If the home is more than a few years old and cracks are growing larger, this can be indicative of foundation movement.
Note: No Drywall Repair Yet
Brick and other masonry quickly shows the affects of movement. Masonry’s rigid nature, relatively weak shear strength/mortar bond will quickly alert you if your foundation is moving. If your home has brick, look for stair-step cracks, vertical cracks, or where the brick appears to be pulling away from the wall. Hairline cracks typically do not require immediate action but should be carefully monitored for future movement. If the cracks are bigger than 1/8”, or seem to be growing, you should contact VMC for a free assessment.
Note: No Mortar Repair Yet
It is important to distinguish between framed floors and concrete floors poured on grade: If your framed floor is out of level to the point where you notice it, it could be due to vertical foundation movement and you should call VMC for a free assessment. Framed floors bear directly on the foundation, either by attaching to the foundation wall or sitting on it. Framed floors can be basement floors; these floors tend to be in homes built after about 1990. You can identify a framed basement floor if you have a crawlspace underneath it (it can still have a concrete surface and steel floor joists). With any of these floors if there is slope to the floor, it is probably due to foundation movement. In Colorado, many homes were built with slab-on-grade basement floors: these floors are concrete poured directly on top of the basement soil and the slabs tend to be independent of the foundation. If your slab is moving a little, that is to be expected and is only of structural concern if the slab’s movement is pushing on an element of the home. Usually we can correct a slab’s movement with injection of a poly foam or Portland-modified sand (commonly called foam-jacking or mud-jacking, respectively).
Windows & Doors Sticking
If your windows or doors used to open and close easily and are now tight or rubbing, you could be experiencing foundation movement. Call Van Matre Construction for a free assessment.
How We Fix It
VMC uses a variety of methods to stabilize foundations and return them to level. One of the most effective, efficient, and cost effective methods is with helical piers. Helicals allow us to literally screw through low load bearing or swelling soil near the surface and reach down to competent soil or even bedrock. With helicals placed along the edge of a foundation, we can transfer all of the building’s weight onto these deep soil or rock layers, bypassing the upper layers of soil the foundation was originally built on. The limitation of helical piers is typically depth or when rocky soil is encountered. If the soil is expansive but very dense, we have a tough time getting the depth we need to get past any potential swelling layers. Rocks can also stop a helical pier from advancing. In these cases, micro-piling may be necessary. Micropiling allows us to drill further down into the earth than is possible with a helical pier with depths as deep as sixty to eighty feet being possible
Push Piers: A push pier, also known as a resistance pier, is typically a cylindrical steel column that is advanced into the soil using hydraulic rams and the weight of the structure to push the pier down into the earth. Push piers are typically faster, easier to install and less expensive than helical piers or micropiles. Push piers have limitations and are only effective in the right type of soil: They offer no resistance to uplift (resistance to heaving caused by swelling soils). They can only be advanced into soil with the weight of the structure they will eventually support, meaning the best you can hope for is a balance of forces. A push pier’s bearing is entirely on the end of the pier: in most cases this is a 3” circle. The pier is pushed down with the weight of the structure until the resistance of the soil is sufficient to start to move the structure up. This means that should the soil lose some of its capacity; either through wetting or drying, the pier can easily penetrate deeper, causing the structure to settle further. If there is any uplift from swelling soils, the pier sections can easily separate from each other. If you are in an area where you have loose, unconsolidated soils overlying relatively shallow non-expansive bedrock, push piers might be a good solution. But if you have this type of soil, you probably do not live on the front range of Colorado. In the areas where we tend to see the most foundation problems, we frequently see relatively dense, but still expansive soils overlying denser, expansive soils. To get to a stable zone of soil requires depth that is typically not possible with a push pier. While push piers are more economical than helical piers, the savings is not great enough to justify their limitations and that is why Van Matre Construction will not install push piers.