Foundation Crack Diagnosis

basement wall crackConcrete basement wall with crack

Foundation crack diagnosis begins with determining and evaluating not only the type of material your foundation is made of, but the size, shape, and location of your foundation crack. Foundations are designed to carry the weight of the building down to the footings. Diagnosis will help you determine the probable cause of the crack, which you will need to know to solve the cause of the problem.

The purpose of foundation crack diagnosis is to help determine why the crack occurred and what steps need to be taken to fix the issue that caused the crack. Is the problem due to foundation movement? If so, what type of movement is it? It could be leaning, settling, heaving, or bowing. Or do faulty materials cause the issue? Commonly used foundation materials include concrete, concrete block, cinder block, and reinforced concrete. Another part of foundation crack diagnosis is the degree of crack severity. Is it a hairline crack? Is the crack large enough to stick your fingertip into, about 3/8ths of an inch or wider? And most importantly, does the crack affect the building’s stability?

Signs of Foundation Cracks Above the Grade

Sometimes foundation issues will show up as smaller problems in a home. There may be a door or window that seems to stick. Maybe they have a wider gap on one side then they do on the other. Foundation settlement will usually cause cracking in walls. Sometimes floors will slope or tip towards an outside wall. These can all possibly be signs that there may be cracks or problems with a home’s foundation and requires further inspection.

foundation crack diagnosisCrack in door frame and wall

Types of Foundation Cracks And Their Severity

Shrinkage cracks, which are usually vertical in nature, are usually uniform in width and stop before reaching the bottom of the foundation. These types of cracks are a result of expansion and contraction. They are not as serious as horizontal cracks unless the cracks are wider at the bottom than at the top. This condition usually indicates a settlement problem under the building.

Settlement cracks are usually diagonal and are caused by foundation movement. This movement can be attributed to the ground around the foundation moving or shifting, usually caused by a change in water conditions in the soil, causing the foundation to “flex”. Severe changes in temperature may also cause settlement cracks. Many times diagonal foundation cracks are wider at one end because the foundation is moving in two different directions.

Pressure cracks, horizontal in nature, are the most serious types of cracks. A horizontal crack is usually caused by excessive pressure applied to the foundation’s exterior side, which results in a bowing of the foundation. This exterior pressure can be caused by improper back filling or hydrostatic pressure. I have seen cases where a basement or crawl space floods and is filled with several feet of water, the depth of the water inside will be equaled by the amount of water outside around the foundation. The inside and the outside both have the same amount of pressure being exerted on them. If someone pumps out the inside water quickly, the outside water can exert a greater hydrostatic pressure on the foundation, causing it to bow and crack, or fail completely. Horizontal cracks may also be a result of inadequate reinforcement or support. If you find a horizontal crack in a section of a foundation wall, you should have the entire wall reinforced.

Step cracks are usually seen on concrete or cinder block foundations. They are basically the same as diagonal cracks on concrete, caused by settling. Usually only the mortar between the blocks is affected and can be repaired by removing some of the mortar and applying new mortar. The only thing you should be overly concerned with in this case is if the blocks themselves become displaced or out of alignment with their neighboring blocks.

Faulty Foundation Materials

For the most part, faulty materials are not the cause of foundation cracks. Rarely are there structural defects in concrete or cinder blocks. Unless poured concrete foundations freeze before they cure, the concrete itself should not be an issue. I’m not saying faulty materials never occur, it’s just that problems of this type are rare. If you see flaking on the blocks or poured concrete, that would be a possible indication of faulty material.

Structural Engineers

When it comes to foundation crack diagnosis, a home inspector can review the conditions of a home’s foundation. A structural engineer, on the other hand, is a qualified specialist who can determine the structural integrity of the foundation, and access its potential problems and suggest solutions needed to repair any damage. Structural engineers typically charge somewhere between $300 and $500 per hour. Their services aren’t cheap, but their knowledge is extensive. If a contractor or a home inspector recommends contacting one, a structural engineer can be worth their weight in gold and possibly save you money in the long run. Sometimes an over the phone conversation between you, your contractor, and the engineer will be all that is required to answer any questions concerning your foundation.

Tips About Hiring Foundation
Crack Repair Specialists

This is a list of things you need to know about the person or company that is going to repair any foundation cracks you may have.

  1. Training: Has the company and its technicians received training and certifications in the field of foundation crack diagnosis and repair?
  2. Crack Analysis: Is their analysis and plan for repair backed up by the opinion of a structural engineer?
  3. Industry Standards: Inspections and suggested repairs should follow an industry standard. The last person you need is a “fly-by-night” expert who is no expert at all.
  4. Understanding Local Conditions: Soil types and building practices vary across the country. What works in the Midwest may not be appropriate for New England. Make sure the person or company you hire to repair any foundation cracks has plenty of “local” knowledge.

If it is a small crack and you are thinking about trying to repair the crack yourself, read how to repair small concrete foundation cracks.

In Conclusion

Foundation crack diagnosis can be tricky. The structural integrity of your home depends on a strong and stable foundation. You may see the crack and think you know what the issue is, but the advice of an expert is recommended. If you would like to speak with a local expert in foundation crack diagnosis and repairs, you can call 877-960-0491 any time, day or night. They will come to your home and give you a free inspection and estimate for repairing the damage.

Additional Reading:

Foundation Repair Cost
Landscape Drainage Issues
Gutter Drainage Issues

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NAFRA - National Foundation Repair Association
CFA - Concrete Foundation Association

Written by Mark Huey.