Foundation repairs, in general, are different from wall repairs. Even if you do not own an adobe home, if you have cracks in your foundation wall(s), this information will help you. Please read my other page titled “Crack repairs” for an overview of cracks.
Before deciding and embarking on a repair strategy for a crack(s) in your foundation, remember the first rule: determine why, if possible, the crack or cracks are there in the first place. Putting money into a crack repair without first determining why or how the crack was formed in the first place could very well be a waste of money. One must solve the issue with why the problem is there in the first place before trying to repair the cracked foundation.
Cracks in foundations can vary from being insignificant (needing no repair) to serious in nature, requiring extensive repair. As I wrote about in my page titled “Crack repairs,” hairline cracks in your foundation are not a cause for serious concern. Concrete by its very nature is prone to cracking, which is why in concrete sidewalks, for example, you find control joints placed throughout them. These control joints are not simply decorative in nature but are there for a reason: they help to control the inevitable cracking that comes from poured concrete.
Another important question to answer is this: are the cracks structural or non-structural in nature? As stated above, an insignificant crack is also non-structural in nature, while a serious crack is structural.
1. Cracks in walls due to water damage
First, let’s address a serious crack, or one that is structural in nature which requires immediate or near immediate attention. In other words, a crack that if not remedied will result in a dangerous, unsafe condition for the people living and/or working in the home or structure.
Such a crack can be found in a corner of an adobe house which, for example, has experienced a sudden shift in weight which has caused a diagonal crack to appear that may run from the top of the wall down to the foundation. Such a crack could begin at the base of the foundation and have a width that, as the crack extends up the wall, increases or “opens wider” so that the width of the crack is significantly wider at the top of the wall than at the bottom, or base, of the crack.
If you can readily tell that the top of this wall is clearly out of plumb with the rest of the wall, or that the wall is “bowing out,” you may have a serious–and dangerous–situation on your hands. Imminent collapse of this section of the structure could happen at any time. Not only this, but the roof structure that this portion of the wall is supporting could also collapse, resulting in a domino effect that could result in catastrophic results.
A CASE STUDY
I was called out to look at a mud adobe house that was built before 1950. A stucco coat had been applied over the adobe. One corner of the house had a large vertical crack that ran the height of the house from foundation to roof. This crack was about four to five inches in width at its widest part and it appeared that it would break free from the house at any moment…a frightening scenario.
The owner of this rental unit explained that he recently had the roof redone. When they put the swamp cooler back on, it leaked. This tiny amount of water that came from the leaking cooler followed the slope of the roof down to one of the scuppers where it drained off the roof.
The problem was that the roofers did not pay close enough attention to the roof where it met the scupper; instead of insuring that this small area was absolutely waterproofed and correctly finished, they carelessly left a small opening between the roof and the metal scupper. When I write “small,” that is exactly what I mean: small. Just a tiny crack that one could hardly notice if you were not looking for it.
The water from the leaking swamp cooler unit trickled through this crack and instead of harmlessly going out the scupper and down to the ground, dripped into the top part of the adobe where the mud adobes met the corner of the roof. The stucco was also cracked at this point, that covered the adobe parapet top, so the water was able to penetrate in this location.
This entire corner of this mud adobe home became saturated with water from the leaking cooler until at a moment in time, became so heavy that it cracked free from the rest of the house, leaving crumbled adobes and stucco at the base. You could clearly see the water stains that darkened the adobes, and the adobes that fell to the ground were soft and wet.
This type of catastrophic failure was beyond the scope of even my expertise and would require several experts to solve this problem: a structural engineer and a general contractor who possessed the necessary experience and crew to reconstruct this corner. Because that corner of the house was in danger of falling down at any moment, emergency shoring was needed to prevent the walls and roof from sudden collapse. I contacted the owner and shared with him my findings, giving him the name of a contractor who I knew to have a good reputation in this type of extensive repair.
Concrete will crack, no matter how expertly it is laid down or the quality of the concrete mix. Concrete does two things: it gets hard and it cracks. When control joints are placed throughout the slab, this inevitable cracking will occur in these control joints and hopefully will not be sporadically spread throughout the project in an uncontrolled manner.
But in your typical poured foundation, control joints are not found; these concrete stem walls are mono ethically poured, or poured all together at the same time with no control joints placed in them. Because of these lack of control joints, hairline cracks are common, even expected and are usually no cause for alarm.
Nor is it unusual to have cracks in your foundation that are larger than hairlines. Even large cracks, depending on where they are and what caused them, may not be a cause for undue alarm. This is why it is imperative that you discover what caused the cracks in the first place and whether or not water is penetrating into the crack themselves, if at all.
Cracks in your foundation walls become serious when several factors come into being: 1. a tree that is growing near the foundation wall is causing the crack; 2. a crack that is larger than 1/8″ is in an area where water is ponding; 3. a large crack in the foundation wall is part of a basement wall or a lower story of your house.
2. Cracks in foundation walls caused by roots or trunk of a tree
As discussed elsewhere on this site, roots from a tree can cause severe damage. If a tree is determined to be the cause of the crack, you must take care of this problem first before tackling the crack repair. If not, you are throwing your money away; the growing tree will only continue to exert pressure on the crack, eventually ruining the crack repair, regardless of how expertly the crack was repaired.
Don’t automatically dismiss the possibility of a relatively small tree with a narrow trunk being the cause of the crack in your foundation wall. You will be surprised to discover that a comparatively insignificant tree is capable of sending out roots that can be the cause of cracking a solid foundation wall.
If the roots or trunk of a tree is determined to be the cause of the crack, there is a good chance that these same roots will be the cause of the concrete floor buckling or developing cracks on the inside. Always inspect, if possible, the floor directly opposite any significant foundation crack to make sure there is not additional damage that will need to be repaired.
This is not to suggest that tree roots or trunks are always the cause of foundation cracking or buckling of the floor on the inside of your home, but is just one of several possibilities. Again, determining exactly why the cracks are there in the first place is critical to a permanent solution to these problems.
3. Cracks in foundation walls caused by settling
Foundation cracks can be caused by settling, or the weight of the structure itself “sinking” into the ground. This can occur due to several reasons: 1. seismic shifting of the earth caused by any number of natural reasons, such as an earthquake, landslides, sinkholes, etc.
These types of cracks can be difficult to determine whether or not they are “live” cracks (cracks which continue to open up in a consistent or semi-consistent manner) or “dead” cracks (the cause of the crack will probably not be repeated and the crack will not grow wider or longer).
A “live” crack should not be repaired unless it is necessary for safety reasons. As I discussed elsewhere, repairing cracks that continue to open are an unwise use of money due to the fact that you will have to continue repairing the cracks.
An excellent way to monitor cracking to determine whether they are alive or dead is by using a crack gauge.
A crack gauge or monitor is a simple instrument, relatively inexpensive, that you can use to monitor the crack in question, allowing you to accurately measure whether the crack is increasing in width or not. Using a crack gauge can take the guesswork out of determining whether or not the crack is one that is alive or dead.
The longer a crack gauge or monitor can stay on a crack the better. If I had to put a minimum amount of time on a crack to determine whether it was alive or dead, I would say that twelve months would probably be the minimum before I removed it. This will allow for a full cycle of freeze/thaw seasonal changes.
Regular readings on the installed crack monitor are important to insure accurate measurements and accessing whether or not the crack is widening or remaining the same. Again, taking the guesswork out of determining whether or not a crack is continuing to open is important in determining whether you will spend the money to repair the crack or continue to monitor any possible movement of the foundation.