Foundation and Structure Cracks

Anthony Perry's Inspections can advise you of the potential problem and the solution for the repair. Our inspection of slabs conforms to industry standards. We examine the visible portion of the stem walls on the exterior of the structure for any evidence of significant cracks or structural deformation. However, we do not move furniture or lift carpeting and padding to look for cracks, and we do not use any specialized tools or measuring devices to establish relative elevations or determine any degree of differential settling.

Significantly, many slabs are built or move out of level, but the average person would not realize this until there is a difference of more than one inch in twenty feet, which most authorities describe as being tolerable. Interestingly, many slabs are found to contain cracks when the carpet and padding are removed, but there is no absolute standard for evaluating them. However, those that are less than 1/4" and which exhibit no significant vertical or horizontal displacement are not regarded as being structurally threatening. They typically result from common shrinkage, but can also be caused by a deficient mixture of concrete, deterioration through time, seismic activity, adverse soil conditions, and poor drainage, and if they are not sealed they can allow moisture to enter a residence, and particularly if the residence is surcharged by a hill or a slope, or if downspouts discharge adjacent to the slab. However, in the absence of any major defects, we may not recommend that you consult with a structural engineer or a foundation contractor, but this should not deter you from seeking the opinion of any such expert, and we would be happy to refer one.

A similar narrative appears with raised foundations. Such narratives not only educate clients but also sensibly limit the responsibility of inspectors, who are not geo-technical specialists and should not be expected to accept the responsibilities of a specialist. For instance, how many inspectors are likely to be aware that American builders continued to use an inferior sand-lime mixture for many years until the development of pressure testing at the turn of the twentieth century proved that Portland cement, which was invented by an Englishman in 1824, was vastly superior. It was simply a case of a cultural bias. All foundations are not equal. I have poked my finger into some that were built at the turn of the twentieth century that had the consistency of a crumb cake. This is why informative narratives are essential, and why any defect in the components of a foundation needs to be carefully documented, and why I favor the use of computer-generated narrative reports, in which an inspector can store endless amounts of narratives that can appear with a simple click of a mouse. And these same narratives can also be used as a reference library in which inspectors can look up information that they could not possible hope to remember. But let’s consider the common issue of cracks in a slab foundation.

Some inspectors may be inclined to believe that small cracks, which are typically the result of shrinkage, are not worth noting. However, consider the following case involving a house with slab on-grade foundation in a neighborhood with no apparent geological issues, no cracks in the streets, no broken curbs, nothing. The house had been completely renovated, and appeared to be in perfect condition. It was tastefully furnished, and had a new roof, new windows, new doors, and new carpeted and tiled floors, to name the major improvements. The only visible blemishes were cracks in an old patio slab that could have resulted years earlier, due to the absence of expansion joints, the installation of which was not in common practice when the house was built.

A year later, a specialist evaluation of the same property confirmed that expansive soils were raising and lowering the house as though it were floating on water, and in a sense it was. Doors had shifted out of square, and cracks radiated from every opening. Some cracks in patio slabs, walkways and driveways, are not necessarily a cause for alarm. They result from moderate ground movement, which builders try to accommodate by cutting in expansion joints at every eight feet or so, but inspectors should never make assumptions about such things. They should at least inform their clients about them, and recommend that they seek a second opinion.

Shrinkage cracks are common in slab foundations, and are usually quite small. However, it is not unusual to find larger ones where the slab meets the footing. These are referred to as cold-joint separations, and are usually not discovered until carpeting and padding are being replaced. Because of their size, they can seem structurally alarming but they’re really not and are easily repaired with non-shrink grout. However, people have been reported to become hysterical, believing that their house is about to fall down, or that the seller had deliberately concealed defects that the inspector should have magically known existed. It’s a recurrent nightmare for those inspectors who have tried to convince a disgruntled client that such cracks have little significance. The truth is that all cracks are structural but not all of them are structurally alarming, and people really do need to be educated and cautioned about them, no matter how small, in which case their response is likely to be rational instead of hysterical.

We should not leave the subject of foundations without talking about sloping floors. Some floors are built out of level, and some are caused by differential settling, which is a result of weight bearing down on footings situated in soils that are either inherently unstable, inadequately compacted, or have become destabilized by moisture. Significantly, most builders pay little attention to weight, and could only guess at the weight of a house, whereas a shipwright could tell you down to the last pound what a ship weighs. Consequently, houses do have a tendency to settle, usually listing to one side, or settling more or less equally on opposing sides, which leaves floors crowned in the center. Similarly, many structural engineers agree that one inch of slope in twenty feet is tolerable, and report that differences in elevation are typically not noticed until it exceeds this.  

Foundation Inspections

Anthony Perry's Inspectors has spoken to numerous homeowners that have told stories about instances that happened in the during the night. The stories are all  similar according to their descriptions. They are awakened by a crack or pop. Part of their house cracked like a dry piece of kindling wood. However, often the part that cracked is the foundation.

They also speak about door and windows that work perfectly one day and stick the next day. Sometimes the sticking is seasonal. That is, the doors and windows work fine for three to four months and then trouble begins. Magically, the doors and windows work fine four to six months later.

In all these cases, the common denominator is some form of major structural movement. The movement can be within the house or it can involve the entire house.

All too often, however, the term settlement is used to describe any movement. This can be misleading, as settlement is really just one form of movement which can affect the way the inside and outside of your house looks. Cracks can develop in your house from other forces such as landslides, heaving frost or soil swell, soil shrinkage, erosion of soil from beneath your foundation, earthquakes, construction blasting, soil creep, etc. You see, lots of things can be happening! Sometimes, two or more at once.

Common Causes

It is not uncommon for a house to be built on fill dirt or on a hillside. Have you seen huge earthmoving machines working on a new subdivision? They scrape dirt from the high spots and deposit it on the low areas. The dirt that is used for fill is supposed to be compacted. However, it may not always be. Gravity and water entering the soil over time compacts the loose fill. If the compaction is not the same under the entire foundation, your foundation may fracture.

Hillside construction is a simple matter of high school physics. Gravity is constantly pulling the soil down the hill. I learned this in my first geology class. This soil creep, as it is called, takes place at a faster rate the closer one is to the surface of the ground. So, houses dug into a hillside basically have their backsides exposed! The part of the foundation that is shallow and is near the surface is subject to movement, while the remainder of the foundation is quite stable where it is dug deeply into the hillside. Perhaps you have seen foundation failures like this.

Hillsides also pose another problem. The soil creeping down the hillside can exert huge forces on the uphill part of the foundation. These walls can crack or tilt inward from the force of this pressure.

Water, or the movement of water in soils, can cause foundations or slabs to crack as well. For instance, imagine if a sewer line or water line that runs beneath your house develops a leak. It erodes soil from beneath your house and floor. Eventually the foundation footer, wall, and/or floor cracks in response to the absence of the support. Remember, your foundation was designed to work with adequate support beneath it.

Certain parts of the nation have clay soils. Some of these clay soils shrink and swell in response to the amount of water they contain. This movement can be dramatic. As the soil beneath your foundation dries out, your foundation drops. In wet weather the clay swells and lifts your foundation. This is no problem if the movement is the same at every point along your foundation. In more cases than not the movement is not equal. Stress builds and your foundation cracks.

Solutions

If your foundation develops a crack or a fracture, it usually can be stabilized. If the crack is vertical or diagonal, it may require a support from beneath that cradles the footer or foundation. If your foundation develops a horizontal crack, it can be stabilized in several ways as well.

In all instances, it would be wise to consult with a licensed structural engineer who specializes in residential problems. If you try to solve the problem yourself, or merely trust the workmen, you may have a problem occur at a later time. Some of the solutions can actually transmit the stress of the problem to another portion of your foundation. These cracks may happen months later. The contractor will generally say that those are not his fault, when, in fact, they may be! 

Some inspectors may be inclined to believe that small cracks, which are typically the result of shrinkage, are not worth noting. However, consider the following case involving a house with slab on-grade foundation in a neighborhood with no apparent geological issues, no cracks in the streets, no broken curbs, nothing. The house had been completely renovated, and appeared to be in perfect condition. It was tastefully furnished, and had a new roof, new windows, new doors, and new carpeted and tiled floors, to name the major improvements. The only visible blemishes were cracks in an old patio slab that could have resulted years earlier, due to the absence of expansion joints, the installation of which was not in common practice when the house was built.

Vertical cracks in foundation walls are relatively common, and typically result from shrinkage. However, those in the above pictures that were taken from inside a garage are probably seismically related, but not everyone agrees on the significance of such cracks. And when money is involved, opinions can range from rational to ridiculous. A veteran foundation contractor that I once knew paid little attention to such cracks unless there was a significant degree of rotation, but that was in a less litigious era. He would explain how they occur and sometimes pacify his nervous clients by explaining that he had to crawl through an eighteen inch crack in the stem wall, meaning the screened foundation access hatch, to enter the crawlspace. However, there are issues besides cracks that inspectors need to be concerned about. For instance, if the soils around a foundation extend above the footing and do not slope away for a distance of at least six feet, structural problems could result, as you can see from the picture of a foundation wall that was taken from inside a crawlspace. Soils were piled high on the outside of the stem wall that allowed moisture to pond, penetrate, and eventually deteriorate the concrete to a point that exposed the rebar, as you can see from the picture.

Shrinkage cracks are common in slab foundations, and are usually quite small. However, it is not unusual to find larger ones where the slab meets the footing. These are referred to as cold-joint separations, and are usually not discovered until carpeting and padding are being replaced. Because of their size, they can seem structurally alarming but they’re really not and are easily repaired with non-shrink grout. However, people have been reported to become hysterical, believing that their house is about to fall down, or that the seller had deliberately concealed defects that the inspector should have magically known existed. It’s a recurrent nightmare for those inspectors who have tried to convince a disgruntled client that such cracks have little significance. The truth is that all cracks are structural but not all of them are structurally alarming, and people really do need to be educated and cautioned about them, no matter how small, in which case their response is likely to be rational instead of hysterical.

We should not leave the subject of foundations without talking about sloping floors. Some floors are built out of level, and some are caused by differential settling, which is a result of weight bearing down on footings situated in soils that are either inherently unstable, inadequately compacted, or have become destabilized by moisture. Significantly, most builders pay little attention to weight, and could only guess at the weight of a house, whereas a shipwright could tell you down to the last pound what a ship weighs. Consequently, houses do have a tendency to settle, usually listing to one side, or settling more or less equally on opposing sides, which leaves floors crowned in the center. Similarly, many structural engineers agree that one inch of slope in twenty feet is tolerable, and report that differences in elevation are typically not noticed until it exceeds this.

Foundation Tree Damage

Although trees are generally a desirable feature of home landscaping, they can pose a threat to buildings in a number of different ways. Inspectors may want to educate themselves about tree dangers so that they can inform their clients about potentially dangerous situations.

Tree Roots and Foundations

Contrary to popular belief, Anthony Perry's Inspectors have found that tree roots cannot normally pierce through a building's foundation. They can, however, damage a foundation in the following ways:

  • Roots can sometimes penetrate a building's foundation through pre-existing cracks.  

  • Large root systems that extend beneath a house can cause foundation uplift.

  • Roots can leech water from the soil beneath foundations, causing the structures to settle and sink unevenly.

Other Dangers:

  • Trees that are too close to buildings may be fire hazards. Soffit vents provide easy access for flames to enter a house.

  • Leaves and broken branches can clog gutters, potentially causing ice dams or water penetration into the building.

  • Old, damaged or otherwise weak trees may fall and endanger lives and property. Large, weak branches, too, are a hazard, especially if weighed down by ice. 

  • Tree roots can potentially penetrate underground drainage pipes, especially when they leak. Water that leaks from a drainage or sanitary pipe can encourage root growth in the direction of the leak, where the roots may eventually enter the pipe and obstruct its flow.

  • Trees may be used by insects and rodents to gain access to the building. 

  • Falling trees and branches can topple power lines and communication lines.

 
Structural Defects in Trees

Trees with structural defects likely to cause failure to all or part of a tree can damage nearby buildings. The following are indications that a tree has a structural defect:

  • dead twigs, dead branches, or small, off-color leaves;

  • species-specific defects. Some species of maple, ash and pear often form weak branch unions, while some other fast-growing species of maple, aspen, ailanthus and willow are weak-wooded and prone to breakage at a relatively young age;

  • cankers, which are localized areas on branches or stems of a tree where the bark is sunken or missing. Cankers are caused by wounding or disease. The presence of a canker increases the chance that the stem will break near the canker. A tree with a canker that encompasses more than half of the tree's circumference may be hazardous even if the exposed wood appears healthy;

  • hollowed trunks;

  • Advanced decay (wood that is soft or crumbly, or a cavity where the wood is missing) can create a serious hazard. Evidence of fungal activity, such as mushrooms, conks and brackets growing on root flares, stems or branches are indications of advanced decay. A tree usually decays from the inside out, eventually forming a cavity, but sound wood is also added to the outside of the tree as it grows. Trees with sound outer wood shells may be relatively safe, but this depends on the ratio of sound-to-decayed wood, and other defects that might be present; 

  • cracks, which are deep splits through the bark, extending into the wood of the tree. Cracks are very dangerous because they indicate that the tree is presently failing;

  • V-shaped forks. Elm, oak, maple, yellow poplar and willow are especially prone to breakage at weak forks;

  • The tree leans at more than 15 degrees from vertical. Generally, trees bent to this degree should be removed if they pose a danger. Trees that have grown in a leaning orientation are not as hazardous as trees that were originally straight but subsequently developed a lean due to wind or root damage. Large trees that have tipped in intense winds seldom recover. The general growth-form of the tree and any uplifted soil on the side of the tree opposite the lean provide clues as to when the lean developed.

 

Tips that inspectors can pass on to their clients:

  • Binoculars are helpful for examining the higher portions of tall trees for damage. 

  • When planting trees, they should be kept far from the house. It is impossible for the homeowner to reliably predict how far the roots will spread, and trees that are too close to a building may be a fire hazard. 

  • Do not damage roots. In addition to providing nutrition for the tree, roots anchor the tree to the ground. Trees with damaged roots are more likely to lean and topple than trees with healthy roots. Vehicles are capable of damaging a tree's root system.

  • Dead trees within the range of a house should be removed. If they are not removed, the small twigs will fall first, followed by the larger branches, and eventually the trunk. This process can take several years.

  • Inspect your trees periodically for hazards, especially in large, old trees. Every tree likely to have a problem should be inspected from bottom to top. Look for signs of decay and continue up the trunk toward the crown, noting anything that might indicate a potential hazard.

In summary, trees that are too close to buildings can potentially cause structural damage. 

© 2020 Anthony Perry's Inspections LLC

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15764 Walnut Creek Drive, Strongsville, Ohio 44149

Email: anthony@inspectors.property

Anthony Sr. Tel: (216) 246-8787

Anthony Jr. Tel: (512) 779-8634

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Anthony Perry Sr. License Number: OHI.2019004370
Anthony Perry Jr. License Number: OHI.2019005307